|
Warehouse managers often ask, “Does RF Data Collection give me the same optimization benefits as a Warehouse Management system?

The question to return is: “Who is faster (has lowest amount of labor)? The picker who picks via paper, or one using a radio frequency (RF) device?”
The answer is the paper picker. He/she doesn’t have to unholster, scan, and holster the RF device. So RF Data collection doesn’t optimize labor, it just provides a more accurate process. You have to have tools to improve accuracy, as well as optimize labor (work flow).
So how do you gain high inventory accuracy, high asset utilization, and labor optimization in your distribution center? Via a combination of warehouse management, and best practice business processes. Warehouse management solutions, unlike RF Data Collection, can execute best practices in real time that give you the accuracy, labor, and space optimization you desire. They can also react in real time to unexpected errors, correct them immediately, and put a plan in place to address the error (alert, cycle count, etc.).
So the answer is “No, RF Data Collection does not give you the same benefits as WMS.” RF is just a tool to be used when having good WMS processes. Implementing RF without good WMS processes will not give you the benefits that you are seeking.
At the end of the day, the best approach is to find a company with the type of supply chain management consulting skills and experience to help you determine the best approach. An approach that targets the most critical KPI’s for your business. If you can find a trusted supply chain expert, you can drive business value around your specific needs.
Source : article from Bill Ducat on March 8, 2011
It is time for a more technical Dynamics AX posting here. I want to describe what was needed to be done to upgrade a very complex solution, that consist of several ISV solutions and also have local customizations on top. Overall, the task can be visualized like this.
The upgrading was related to new Rollup package from Microsoft, new releases of the ISV solutions; RCM from Microsoft, WM&D from To-Increase and Inventory II from FSB development. My biggest concerns was:
- The ISV solutions needed to be merged into common layers. This results in different TableID and FieldID.
- Several fields and tables had been renamed in the ISV solutions.
- The risk of loosing data in the process is high, unless I get the mapping right.
- The database is approx. 1 Tb large, so table changes etc is very heavy operations.
There is a central table in Dynamics AX 2009, called SQL dictionary, that translates AOT ID’s to actual SQL names.
And you can see this in the application like this:
When going from old solution to new solution I needed to make some changes in the SQL dictionary to make sure that I don’t have any dataloss. Since Dynamics AX 2009 are quite good to handle changed table names and field names, I could concentrate on making the new mapping correctly in the SQLDictionary.
Here is what I did to make this happen. I installed all NEW layers and customizations on a separate installation, making sure that there where no compile errors etc.
The next was to create a conversion tool to manipulate SQL dictionary, that handles both changed ID’s and changed Names. I therefore created a table to handle the SQLdictionary from old format to new format. I created a small table, that looks like the SQLDictionary, and then created New and Old tableID, FieldID, name and SQL name.
The first process was to read this out of the OLD database, with the following script:
So now I have a table that is a “copy” of the Old SQL dictionary. My next step is to correct up all ID’s. To do this, is a painstaking process, because it has to be done manually. So I created 2 methods for manipulating the SPA_SQLDictionary. The UpdateTableId() and UpdateFieldID()
Then I called these two methods to set the new ID’s:
In my case, there where more than 500 tabels that needed to be handled this way. Manually defining from ID. Luckily I could use the Tablename2Id and fieldname2id methods to give me the new ID’s.
The last step in the prosess was to copy the new ID’s into the SQLDictionary:
After this has been done, the system is ready to by synchronized, and all tables and fields have the correct mapping.
With this approach I did not have any dataloss, I did not have to export/import a 1 Tb database J. I also want to point out, that AX 2009 is the last version where we will have this problem. (I hope). In AX 2012 we will have installation specific ID’s, and you can read more about that here.
WM&D have many options for picking. This document describes how you perform picking of items by using what is called the “packaging station”. This step is where the picked items are physically packed into boxes, pallets or other units used for shipments. In this picking process we do all warehouse processes for delivering stock kept items in just one step.
The process includes also making of the relevant information / documents for shipping the goods.

Order Processing
The picking list identifies items to be sent at the same time to the same destination. The picking list can be a consolidation of several sales orders, one sales order or a part of one sales order. The picking process is the same in all cases.
If wave picking is used a group of sales orders are grouped on one picking list to make the picking process more efficient.
For order picking there is only one order linked to each picking list.
Order picking
A sales order has been made and confirmed for delivery. Based on the reservation rules used, the Items on stock will be reserved either when the order is generated or when the picking list is generated. The picking route for sales orders is generated based on the delivery rules in the setup of AX2009.
WM&D can automatically release picking routes through the order processing, or manually release of Picking routes using in the menu <Inventory Management> – < Periodic> – “Release sales order picking”. In the pop-up selection screen fill in the relevant limitations you want to base your sales order selection of.
You will then enter the release sales order for picking screen as showed:
In this screen you select the sales order(-s) you want to deliver and push the – button. Normally it is recommended to use the automatic order processing and the delivery rules to release pickingroute.
Reservation rules relevant for items on stock are not part of this document.
Printing paper based Picking lists
Enter the <Warehouse Management and Distribution> – Module and choose the menu “auto Print Picking Routes” in the section <Periodic>.
Mark the lines you don’t want to process (Push the button in front of the line and hold down <ctrl> if more than one).
Push the button to delete the lines from your selection.
Push the button and the picking lists will be printed.
Picking
In the <Warehouse Management and Distribution> module in the section <Common Forms> you select the menu “Packing Station”.
By using the “Packing Station” in WM&D the picking of items is done directly into the carrier that will be shipped to the customer.
The first step is to scan the picking list number. The picking list number can also be typed manually or selected in the drop down menu. When the picking list number has been entered all lines included on this picking list will appear in the packing station.
Notice that the items is divided into several lines. The reason for this is that it is picked from several different locations.
Select the shipment unit type / Cargo ID you pick the items to (“Enter/scan bar code” field). This is the carton or pallet that will be sent to the customer. This can also be selected by pushing the button.
Scanning of items:
In the system an item can be identified by a barcode. All unique units will be provided by a unique bar code. That means that a bar code will identify the dimensions of an item. In the barcode setup, the quantity is also set. If an item is stored in units with 5 items in each, the barcode on this unit should represent 5 pcs of an item. This is a setup made on the barcode setup. It is important that you follow the number of items picked when items are scanned.
After scanning an item, the Remaining quantity will be reduced by the number you picked.
If for some reason, it is not possible to scan a barcode, the registration has to be done in another way. This can be done by using the buttons “Pick one”, “Pick some” and “Pick all”:
Do the following:
Press to pick one item (or scan item). When using the Pick one button, the system will pick one item at the time. Separate items, not included in a pack can be counted.
Press If you want to pick more than one (you get a pop-up-window where you enter the amount of items you are picking.
Press to pick the complete quantity on the picking list.
Press If you want to cancel the registered picked quantity.
Pack in multiple boxes
If the entire shipment cannot fit into one shipping unit, additional packages must be created. To do this put in the type of the next carton, into the “Enter / scan barcode” field. When entering a package type, a dialog box asks if a new package should be created.
When saying yes to this a new package id will be created. When continuing packing, this new package id will be used. On the tab “All picked lines”, it is shown what package id each line was packed in. On each line the package id can be changed.
Complete packing
As the item lines are fully picked, they will not any longer be listed in the tab “Picking Lines”.
When your Picking is completed the “Complete”-button will be available. Press to finish your packing/picking.
The Complete stage of the packing station process will take the order 2 steps further in the packing and delivery process. The ordered items will go from being physical reserved to actually being issued from the location and into the status delivered. In this step “Pallet label” and “Packing List” will be printed.
When the order has been completed it is no longer possible to cancel the packing of a picking list.
Printing
“Pallet label” and “Packing List” will be printed when the “complete” button is pressed.
Label:
To identify packages, labels can be printed from the packing station. The label holds necessary information about sender and receiver. The label also held the information number of packages on a shipment and package number on of a specific package (for example package number 1 of 3).
Packing slip:
After completing the packing the packing slip can be printed. Packing slip will be shipped together with the goods to the customer. The packing slip list all items and packages on the shipment.
Pro forma invoice:
I some situation it is necessary to have a pro forma invoice shipped together with the goods. Particularly this can be crucial for shipments going across country boarders. It will then be used for custom clearance of the goods. The Pro form invoice is printed by push the Print Proforma invoice button.
Sales order Status
The order is now fully delivered and complete.

Receive station
This document is a manual for using the WM&D Receive station.
The receiving station is made to optimize the receipt process of purchase orders. The purpose of the receive station is to have an effective receipt of large quantities of goods, have a standardized way of handling the goods, and to have a high quality assurance of the process. To obtain this goal, this process is optimized for use with both touch screen and a scanner-device to minimize the usage of keyboard and mouse.
The Receive station supports the standard way Dynamics AX2009 is handles the receipt and the statuses the purchase order lines goes through; open order, arrived, registered and received.
The receive process can be divided into a number of main processes as illustrated in the following picture:
The first is to create a receipt, and to add lines to receive from the corresponding purchase order. The next step is to go through start receiving and post the Packing Slip. At the end the barcode label is printed out.
In the following sections we will go through these processes in details.
Enter the receive station
Go to The module <Warehouse Management and Distribution>, in “Common Forms” choose the menu <Receiving Station>.
Create new
Enter the Receiving Station:
The first step in the receive process is to create the receipt. Click the Create new button.
Register a new receipt:
The purpose of creating a receipt is to select what to receipt. This can be done by different kind of criteria’s.
Select <Purchase Order> in Receive Type.
When selecting <Purchase order> you can select all or a range of order lines on a purchase order to be received. If one single purchase order is to be received it can be selected by using purchase order line. Internal transfers can also be received by using the receive station.
If you plan to receive multiple purchase orders that have been put into one container, you can select <container> in the field receive type. Then all purchase order lines contained on this container will be selected.
The warehouse should be specified and the receiving dock. The receiving dock is the physical inbound dock where the goods are to be received.
A putaway method can also be specified. The reason for this is to tell the system where “putaway messages” should be sent. Messages can be sent to a conveyor system, forklift terminal, handheld terminals or paper.
Depending on the selected receive type, a selection of what to receive can be done. If a container has been selected in receive type, the selection under reference will change to container. If purchase order line is selected, purchase order line will show etc. After doing the selection; click OK.
In the Purchase order field you put in the corresponding purchase order number that matches the delivery you now will receive. Then all the lines from the purchase order will be copied from the purchase order into receipt lines in the receipt document.
A receive header have now been created together with one or more lines to receive.
Check and Post receipt
Start the receive process:
And check all the receipt lines and do necessary corrections to quantity and texts.
Choose for all lines that are delivered according to the suggested quantity or make adjustments on the line under the folder “Receive Transactions”
NOTE: There are some general parameters to setup if we are to accept over and under delivery, and how many percentage we are to accept. These parameters are also valid her, and will be used when closing the receive.
When corrections are done and the quantity for receipt has been checked you confirm the quantities by choosing:
.
Notice the first column in both the header and the lines. These are symbols used as information about the status.
Not started, In progress Complete
To post the Packing Slip for the receipt choose the button .
In the Posting picture an Reference to the receipt a Packing Slip number have to be entered. In this field you put in the Pacing slip from the vendor as a reference.
Barcodes
Before putting the item into stock it must be marked and identified by a barcode tag.
The label with the barcode is printed by using the button
Choose the right number of labels and press “OK” to print the labels
You have now completely received the item(s) and they are available for picking.
This article describes, in detail, how the process Extended ATP is implemented in the To-Increase Warehouse Management & Distribution solution (WM&D).
Process definition
We define ATP as a planning tool to know when a sales order can be shipped, and then the physical reservation, picking and shipping can be started. Available to promise takes the simple availability calculation, adds time phasing and takes into account future scheduled receipts.
Available to promise may be calculated for each day or broken down into larger time buckets. The ATP starts by taking on-hand inventory and add any scheduled receipts. The ATP calculation will then deduct any allocations scheduled prior to the next scheduled receipt (which may be several periods in the future). Subsequent periods without any scheduled receipts will have the same available to promise as the previous period. Subsequent periods with scheduled receipts will generally start with a fresh calculation, ignoring any remaining available to promise from previous periods.
There are many variations on exactly how available to promise is calculated and it is also important to note that available to promise often works independently of allocation/reservation systems. This can sometimes create conflicts since ATP is expecting that the delivery dates should be followed ascending.
ATP Calculations in standard Microsoft Dynamics AX
Microsoft Dynamics AX calculates the available-to-promise (ATP) quantity based on the “cumulative ATP with look-ahead” method. The main advantage to this method of calculating ATP is that it can handle instances when the sum of issues between receipts is bigger than the latest receipt, that is, when it is necessary to use a quantity from an earlier receipt to meet a requirement. By including all of the issues until the cumulative quantity to receive is bigger than the cumulative quantity to issue, the ATP quantity in an earlier period considers the need to use some of that quantity in a later period.
The ATP quantity is the uncommitted inventory balance in the first period and is normally calculated for each period in which a receipt is scheduled. The program calculates the ATP period in days, and calculates the current date as the first date for the ATP quantity. In the first period, ATP includes onhand inventory less customer orders that are due and overdue.
Microsoft Dynamics AX calculates the ATP using the following formula:
ATP = ATP for the previous period + the receipts for the current period – the issues for the current period – the net issue quantity for each future period until the period when the sum of receipts for all future periods, up to and including the future period, is greater than the sum of issues, up to and including the future period.
When there are no more issues or receipts to consider, the ATP quantity for the following dates is the same as the latest calculated ATP quantity.
If all of the dimensions used for an item are not given when the ATP check is done, they might still be specified on the issue and receipts. In this case, in the ATP calculation, the receipts and issues must be aggregated to the existing dimensions, to reduce the number of receipt and issue lines used in the ATP calculation.
The ATP quantity shown is always > = 0. If the calculation returns a negative ATP quantity (for example, if a larger quantity than the available quantity has been promised earlier), the program automatically sets the quantity to 0.
Requested and confirmed delivery date
When a sales order line is registered, the salesperson must enter the requested delivery date. The sales order line processing will then calculate the best ATP date for this order line. The best ATP date is defined as the customers requested date or the date when the line can be delivered in full.
Based on the delivery rule, the operator can select if the customer wants a single full delivery, or a number of part deliveries. If the delivery rules states a complete order, then the worst-case ATP date can decide the confirmed delivery date on the entire order. The worst-case ATP date will then be copied into the confirmed delivery date fields on the sales order and on the lines. This process should happen when the order is confirmed.
Subsequence ATP calculations
If it is not possible to give a line an ATP date, then the ATP date will be set to “zero”. A “zero” ATP date means that this line needs to be manually processed by order management or by planners. This means that the order management must go though the Master planning/MRP to create a receipt. As soon as a receipt is created, the system can give an ATP date to the issue transaction.
Dimensional and level based ATP
In the ATP calculation, the ATP will be given at the lowest level that is specified of the storage dimension. The storage dimension is Site, Warehouse etc. When entering a sales order line and only site dimension is specified, then the ATP calculation will give the ATP date based on the items that is available on that site.
When a sales/transfer order line is physically reserved, then the ATP should be based on the reservation dimensions.
To accommodate this, the ATP will use the dimensions on the sales- or transfer-line to decide what level the ATP should use. At reservation the warehouse will be specified on the transaction.
To omit a warehouse from ATP calculation, then place the omitting warehouses under another site, like QA, returns, production etc.
ATP overview per sales order
After a sales order has been completely entered, it should be possible to give an ATP overview of the sales order.
The overview will show which lines that can be delivered in relation to the customer requested and confirmed delivery date. A differentiation between full, partly and none is visible. The colors “green“, “yellow” and “red” is used to inform the user of delivery status.
- Green means that the allocation is physically reserved and ATP is OK.
- Yellow means that the order line is not completely reserved.
- Red means that the order line is not allocated or the ATP is not OK.
To support the extended ATP, the ATP will provide some additional functions. ATP quantity is available, but for performance reasons this field is omitted in the sales order screen.
ATP overview all sales orders
The form named ATP overview is available to the order management and show what sales orders, and what customers where manual processing and re-planning is needed.
In this ATP overview it is possible to see if an ATP change is possible. This functions like advancing the delivery prior to the expected ATP date. The processing for a new improved ATP date must be a manual process.
ATP delivery rule actions
These actions will be defined under the delivery rule.
The actions are:
ATP quantity change actions:
No action: No actions will be taken based on the fact that a sales order has lost its ATP date or quantity.
Automatic split sales line: If only some items can be delivered at the ATP date, then the system split the sales line so that all lines get an ATP date. Let’s say the customer ordered 10 units, and all 10 could be delivered at the requested delivery date (1/7).
This is backed up by the following receipt from this purchase order:
There also exists a later purchase order of 5 pcs to be delivered on the 15/7:
If the quantity expected on the first purchase order is reduced from 10 to 5 pcs. Extended ATP will then split the sales line into two deliveries, with different delivery dates:
Delay days before split:
This parameter is used to control, that the delay must be larger than X days before Extended ATP will split a sales order line. If delay days before split are set to 0 then the value from the ATP time fence will be used as criteria for splitting the sales order line.
Loss of ATP date actions selections:
No action : No actions will be taken based on the fact that a sales order has lost its ATP date.
Manual reconfirm: When this option is enabled, the automatic order processing will cancel the current order confirmation, and remove the confirmed delivery date on the affected lines will be removed. The document status on the sales order will be set to “none”, and the order management must manually reconfirm the order.
Automatic reconfirm: When this action is enabled, the current order confirmation will be cancelled, and a new order confirmation will be created, and automatically sent to the customer if this is enabled on the customer.
ATP Inquiry overview for kits and BOM items
The ATP calculation does also support the possibility to perform ATP calculations on kits and BOM items. The property of a kit is that it is a phantom item on the sales order. The real items are the contents of the kit, and can be a multi level structure.
The ATP Inquiry forms overview tab is used for doing delivery simulations for kits without creating a sales order. By entering a kit-item, quantity and requested delivery date, the system will show how much that it is possible to deliver on the requested date, and what the delivery date is for the remaining quantity.
The ATP Inquiry form
To use this form, create a line in the “filter” grid, by specifying an item, site/warehouse, quantity and requested ship date. Extended ATP will then calculate ATP date and on hand on the item. The lower grid is used for additional specifications, more particularly when the item is a kitting item, then the full ATP for the kit will be shown here. It is also possible to set the ATP Inquiry form to update in batch.
ATP Algorithms
In standard Dynamics AX there are already an ATP calculation with an algorithm that loads on-hand per dimension, and then loads all issues per date and all receipts per date. This function builds up a table like this:
In standard AX this evaluation is done transaction by transaction, while in Extended ATP this is changed to use more efficient ATP calculations by grouping issues and receipts per delivery date. In addition, when a transaction is physical reserved, it will always get ATP date equals today. This reduces the number of time an ATP calculation needs to be performed.
To keep track of ATP dates, the ATP is in WM&D a field on the sales order line and on the transfer order line. The ATP field is set at order processing, and when an ATP date is set it remains on the sales order line. The ATP date on the sales order line will not be set before the sales order is confirmed.
ATP Algorithms for kitting
Processing ATP on sales orders with kits will be calculated for the lowest items in the kit, and then the “worst case”-items ATP properties will be the ATP for the kit. This is also called “bubble” up.
The ATP “bubble” process will happen as a sub-process to the order processing.
Other high level aspects
Rules for losing an ATP date is an important aspect. The rule for losing an ATP date is that some conditions has been changed. Changing the following conditions will always result in a recalculation for a sales order line:
- Sales Unit,
- Sales Qty,
- Requested receipt date,
- Requested ship dated,
- Confirmed receipt date,
- Confirmed ship date.
When the expected receipts unexpectedly changes (moves in time or a quantity is changed), then there is a risk that the current ATP calculations are no longer valid. It could in these cases result in change of or even removed ATP dates.
When the system needs to change the ATP dates, it needs to recalculate it in the right sequence. The general rule to lose ATP should happen based on FIFO. There are also times when the system will have originated from a “blanket order” or a “reservation order”. To be able to fulfill this rule ATP is based on sorting the orders in “ATP Sequence”. This is a new field that states the sequence for when a sales order was registered.
On the periodical order processing, the system will then be sorted according to this field.
Periodic ATP calculations
Most ATP calculations in WM&D are automated, and are done when an order is order processed. In the normal order processing it is not possible to improve the ATP date because a full ATP recalculation requires visibility on all issues and receipts. For example, when moving a purchase forward in time, it will release a new ATP calculation on all affected orders.
Here the ATP calculation can be monitored, as the ATP calculation is a background process in the order processing framework. It is also possible to manually start an ATP processing on all items with open sales order lines.
ATP FAQ
This section covers information related to ATP, and is described as a FAQ.
|
Question
|
Answer
|
|
When I have zero on stock, I see that my sales lines requested delivery date is set to today +X days ?
|
The ATP calculation works on a time fence. The time fence could be set to X days. If there is not enough on hand, then the ATP will move the delivery date outside the ATP time fence.
|
|
How to I enable Extended ATP
|
In the WM&D parameters you need to enable the ATP marking to enable the extended ATP calculations. Each line must also have delivery date control set to ATP.
|
|
Can each item have different ATP time fences?
|
Yes. On the item master under Default order setting, you can set can enable ATP on selected items, and also set time fence.
|
|
Do ATP also work for kits ?
|
Yes. ATP works on kits, and the ATP is calculated on the bases on the leaf items (Items lowest in the KIT-BOM). ATP is the bobbled up to the top item, that shows the “worst-case” ATP date.
|
|
I see a field called ATP sequence on sales orders, inventory transaction and on transfer orders. What is that ?
|
With extended ATP some orders can be prioritized over others. Let’s say you have a Blanket order, and you release a sales order. Then this released order will have a higher priority than other orders, and will get items before others. The ATP sequence control this, and shows a date + time for when the order or blanket order was created.
|
|
I need to understand the ATP better. What is the best source?
|
ATP is much based on standard AX. Also try to look into the Dynamics AX online manuals.
|
|
I see that the ATP field is transferred down as
estimated date on the inventory transaction. Why ?
|
This happens when the ATP date is delayed in relation to the requested or confirmed delivery date. This will secure a more realistic ATP calculation. When the ATP date on the sales order is moved, then the estimated date on the inventory transaction will also be moved.
|
This article explains system directed put-away in detail; what it is and how it works. The goal of this article is to help the reader understand the concepts and terminology of system directed put-away. In later postings, I also want to show some tricks how to allow both a system directed put-away and a free put-away, using To-Increase Warehouse Management and Distribution for Dynamics AX.
Locating free locations (put-away) is a key capability of a warehouse management system (WMS). Put-away is normally thought of as the process of moving received inventory from the dock, kitting area, or production department to a storage bin. The put-away process is also used to relocate inventory within the warehouse and to replenish dedicated storage bins with inventory from a reserve storage bin. Any time inventory is being placed in a storage bin it is being put away. System directed put-away is when the WMS chooses the destination storage bin rather than the operator.
The benefits of system directed put-away versus operator directed put-away are
- The WMS consistently follows inventory storage rules to improve space utilization and increase storage capacity
- The system consistently follows inventory storage rules to make picking more efficient
- Warehouse workers do not need to be familiar with all of the products the distributor carries in order for inventory to be placed in the correct bin
-
It is faster – the operator does not have to look for a bin that contains the same item or search for an open bin. For example:
- The WMS can determine if the inventory to be put away will fit in the dedicated bin for the item and send the operator there depending on available capacity and/or lot mixing rules
- The WMS can determine if the inventory to be put away will fit in a partially full bin that contains the same item (not the dedicated bin for the item) and send the operator there depending on available capacity, zoning rules, and/or lot mixing rules
A good system directed put-away function finds storage bins based on velocity, storage requirements (refrigerated, hazardous, wire storage system, etc.), and usage requirements. Velocity is how often an item in a specific package configuration (most often called package type) is picked to satisfy sales, transfer, kitting, or production orders. Some examples of package types are carton, pallet, bundle, and bag. There are two key words in the above phrase. The first is package configuration; put-away rules are not just by item, but consider the manner in which the item is packaged as well. The second key word is “picked”. The directed put-away function stores inventory in order to make picking more efficient.
All discussion of system directed put-away is with respect to a single location (warehouse or distribution center). An item in a specific package type at a given location will be referred to as a SKU (stock keeping unit) for the remainder of this article.
An ABC coding scheme is used to assign velocity codes for put-away. A velocity code of “A” is assigned to the SKUs picked most often. A velocity code of “B” is assigned to SKUs picked the next most often, and so on. Note that a velocity code is assigned to a SKU, not an item. For example, a carton of an item could be assigned a velocity code of “A” while a box of the same item could be assigned a velocity code of “C”. Velocity code is not concerned with type of item, weight, dimensions, cost, customer, or vendor; just how often the item is picked. This is a different ABC code than is used for purchasing.
System directed put-away based on velocity stores items picked more frequently in bins that are more accessible (knee to chest high near the shipping dock) and items picked less frequently in bins not as accessible (up high in the back of the warehouse). This reduces travel time during picking which helps to improve picking efficiency.
Package type and storage requirements are considered next when selecting a storage bin. Pallets and individual cartons are usually stored in different areas of the warehouse. The same is true for bundles of threaded rod, spools of wire, and hazardous materials; items that require special storage. Storage areas for cartons may be further broken down for large vs. small cartons or heavy vs. light cartons. Package type and the type of storage used determine the material handling equipment required to put away and pick the inventory.
The third factor to consider for system directed put-away is how the inventory is used. Inventory may be used for sales orders, production, or for kitting. Do orders for clean room supplies only include clean room supply items? If so, then it can be productive to store all clean room supply SKUs together. If sales orders for products from a given vendor only include items from that vendor then it would be productive to store the SKUs from that vendor together. If a customer predominately orders items that only that customer uses, then those customer-specific SKUs should be stored together. Otherwise SKUs should be stored based on package type. No matter how SKUs are grouped for storage (package type, customer, vendor, or type of business) storage bins within each section of the warehouse are selected based on SKU velocity. Other factors can come into play for selecting storage bins, but velocity, package type, and how items are sold work most of the time.
The three factors described above (velocity, package type / storage, and how items are sold) are used to build put-away zone lists. Put-away zone lists tell the WMS how to find a bin for inventory that needs to be put away. There may be put-away zone lists for “A” velocity items stored in full pallet quantities, “C” velocity items stored in boxes, “B” velocity items only used by a single customer, or “B” velocity bundles of threaded rod. Put-away zone lists are specific to a warehouse. Depending on your software you assign a put-away zone list to a SKU or the WMS deduces which put-away zone list to use for each SKU depending on the value of the three factors for the SKU.
A put-away zone list is literally a list of put-away zones. The warehouse is divided into put-away zones. Each put-away zone contains a group of storage bins. The bins in a put-away zone are of roughly equal value for some group of SKUs when the WMS is searching for a storage bin in which to place inventory. For example, a put-away zone may contain bins for fast moving carton items or slow moving bar stock. A section of shelving, floor storage bins, one or more sections of pallet rack, or a cabinet of drawers could be put-away zones.
The first put-away zone in a put-away zone list is the preferred put-away zone for the SKU. The WMS looks first for a bin in which to place the inventory in the preferred zone. If a satisfactory bin is not available in the preferred zone, the WMS looks in the second zone in the list, and so forth, until a suitable bin is found or the put-away zone list is exhausted.
Other rules can come into play when the WMS is looking for a bin in which to place the inventory to be put away.
• The WMS could look for a bin that is dedicated to the SKU first to determine if there is enough capacity available
• The WMS may look for an empty bin in the preferred zone before it looks for a bin with available capacity that already contains the same SKU in another put-away zone
• There could be limitations concerning mixing lots of the same SKU
• Rules about filling a bin that contains the same SKU where the age difference is too great (when there are expiration or recertification considerations) could apply as well
• Additional rules apply to the storage of hazardous inventory
A put-away zone could contain many bins. Each bin in a put-away zone is assigned a put-away bin ranking. The put-away bin ranking tells the WMS which bin is better to choose when the WMS finds more than one bin in a zone in which the inventory could be placed. For example, a bin closer to the dock would be assigned a better (higher or lower depending on your software) put-away bin ranking than a bin that is further from the dock.
Source : http://www.distributionstrategies.net
In the following blog posts I will focus on the picking process in a warehouse. There are extremely many combinations in this area, so it is worth understanding what we meet when we will be out there and selling Dynamics AX. There will be follow up postings posts later with picking options in Dynamics AX and also what picking strategies that are available in WM&D. This article shall lay out a 10 step plan for evaluating the multitude of alternatives available in designing a piece picking system.
Area of Concern
Piece picking is one of the most labor intensive processes within a distribution center and as such, it is a major area of concern for operations professionals. As a result, operations professionals are often asked this question… “Which piece picking method is best?”
For the purposes of this article, piece picking is defined as any order selection process that requires the product (units) picked to be individually handled and/or placed into an outer carton, tote, or other container before shipping.
In comparison to full-case or pallet picking operations, piece picking typically has lower unit volume, lower revenue, and higher labor costs. The higher labor costs are accrued due to the need to open vendor cartons, pick SKUs less densely, erect/pack/seal shipping cartons, and apply carton labels while picking less volume per item than full case or pallet picks. The movement towards just-in-time supply chains and the proliferation of direct-to-consumer catalog/internet fulfillment operations is driving a change in order profiles. Smaller orders (those with fewer line and piece counts) are being received more often in many industries and market channels.
To design or re-design a picking operation, one needs to develop a cost versus benefit analysis to include the systems to be considered. In order to fully analyze the nearly innumerable alternatives available, one can follow a 10 step plan to narrow down to the feasible options as illustrated below:
Step 1: Selection of Possible Storage/Picking Types
Mine available historical operational data, apply design year projections, and profile item inventory, movement, & unique characteristics to determine the alternative pick types available (cubic velocity by SKU). In an over-pack picking system high density drawers, bin shelving, carton flow rack, vertical lift modules, and carousels may be among the candidate infrastructure to be considered.
Systemic support and overall capital budget constraints may eliminate some of the more mechanized alternatives. The matrix below provides some high-level rules of thumb for pick type selection.
Step 2: Mode of Order Transportation
There are two common options in selecting the method used to transport the order to and from each pick location:
- Pick to cart
- Pick to conveyor
A decision is typically made based on the overall size of the piece picking area (travel requirement). SKU velocity, pick density, and related considerations often define the appropriate method.
A combination or hybrid of the pick to cart/pick to conveyor option is commonly used, in which, fast pick items would be picked to conveyor and slow picks would utilize a cart. Conveyor could be used to transport orders to and from each cart pick zone. The picker may load the cart at the beginning the zone and unload to cartons or totes to conveyor at the end of the zone.
Step 3: Selection of Picking Technology
Operations with a large number of picks in a small area benefit the most from pick to light technology, while operations with picks spread across a large pick area (many pick facings) are better suited for either RF or voice picking.
The benefits of voice versus RF is that voice is “hands free”, the picker never has to put down (or holster) an RF device (scan gun) to either pick or open cartons. In a voice system, picking time can be reduced by the picker listening to the voice directive while traveling to the next location instead of stopping to read the RF device.
The RF device, however, has the ability to capture detailed item information, typically a production batch or serial number, quickly by scanning item barcode labels. Voice may be more cumbersome in these applications.
Step 4: Order Batching
Order batch picking is the process of grouping orders together to create a larger pick order, which reduces the overall pick lines in an operation versus a discrete order pick (picking of one order at a time). Since multiple orders are being picked into one container, in most cases this will result in the requirement for an order sortation station, an area designed to split the pick order into the individual customer orders (discrete orders). If the order batch contains all single unit orders or all orders of the same item, the batch will typically not require a separate sortation station, the items are allocated to a specific order at the time of packing or manifesting. Hardware costs based on number of users, not locations Hardware costs based on number of users, not locations Hardware costs based on number of users, not locations Hardware costs based on number of users, not locations
Step 5: Batch Sortation Technologies
Much like the picking technologies, batch sortation can be performed utilizing paper, RF, voice, or a put-to-light system (which is a reverse of a pick-to-light system). Since a piece pick batch sortation is typically in a condensed area, usually consisting of sections of carton flow rack or shelving, the methods that are most commonly used and are the most effective are RF and put-to-light. Put-to-light is more expensive, but the productivity rates are considerably higher, 100-150 lines/hr for RF versus 200-over 250 lines/hr for put-to-light (broad industry estimates).
Step 6: Cluster Picking
Cluster picking is a methodology of picking into multiple order containers at one time. The containers could either be either totes containing order batches, discrete order shippers, or discrete order totes. There are two main piece picking systems that benefit from the use of cluster picking:
- Pick to cart operations, in which, a cart would be loaded with multiple totes or shippers and the picker will make one pass through the pick zone and sort to the pick containers, thereby avoiding unproductive travel.
- Vertical lift modules (VLM) or carousel operations utilizing the independent zone picking technique, the picker would setup the pick container batch, this would initiate the mechanized pick modules, and the items would be sorted to the proper pick container. This technique is used to optimize the VLM & carousel pods by limiting the number of machine cycles.
Step 7: Cluster Picking Sortation Technologies
The same options and reasoning that applied to batch sortation applies here. The same task is being performed on a smaller level, typically sorting into two to four pick containers. The most common cluster picking system contains a put-to-light cart, whereas the picker utilizes RF or voice picking technology.
Step 8: Select a Picking Container

Pick to tote operations typically utilize order batching & sorting techniques that reduce the picking labor greater than the additional labor required for packaging and sorting. Pick to shipper operations are executed in one of three ways
-
Picker erects the cartons at time of picking. Requires the replenishment of cartons to multiple areas.
-
Cartons are erected and transported to the pickers via separate conveyance system (i.e. monorail). Requires added capital equipment expenditure.
-
Cartons are erected and inducted directly into the system with the contents pre-allocated. Requires extensive systems support.
Step 9: Multiple Pick Zone Order Routing Methodology
Pick to tote operations with order batching lends itself to the independent zo ne pick method, a process in which segments of each order are picked independently in various zones and directed to a consolidation area where the elements of the order are combined to the shipper (batch sortation area).
Pick to shipper or discrete order pick to tote operations are typically most effective in either a pick and pass or zone routed system. This routing method will reduce the overall number of totes or cartons in the system. A zone routed system although more complex and costly, will significantly improve productivity and work flow especially in operations in which an order requires picks from multiple zones. Unlike a pick and pass system, zone routed totes or shippers are only touched by those people in zones where product needs to be picked. All touches are productive as a result.
Step 10: Order Consolidation Methodology
There are several methods with which to consolidate an order before shipping. If your operation is shipping only parcel orders, this might not apply if each carton is shipped independently of each other and no physical consolidation is necessary. For operations that must keep order integrity at the shipping dock, the common techniques are as follows:
-
Consolidate the order before packing occurs when either pre-picking orders before all items are available or discrete order picking to a tote with a 100% order check or to reduce outbound cartons.
- Manual sortation on conveyors – human sortation system, a person is assigned the task of sorting the totes to gravity conveyor lanes typically directed by RF scan
- Automated sortation on conveyors – requiring controls and diverts
- Tote mini-load system AS/RS (Automated Storage & Retrieval System) – stores all totes until order is complete then releases entire order to packing in a “slug” or “train”.
-
Sortation is commonly required after packing, typically for LTL or TL shipments.
- Manual sortation on conveyors – human sortation system, a person is assigned the task of sorting the totes to gravity conveyor lanes typically directed by RF scan
- Automated sortation on conveyors – requiring controls and diverts
Conclusion
Once the options available for your operation are narrowed down a cost versus benefit analysis must be performed for each remaining alternative. Some questions that need to be answered are:
- What is the projected labor cost?
- Does the alternative meet the projected throughput requirements?
- What are the initial capital costs?
- Are there any on-going costs & expenses?
- How much space does this system consume?
- Does it meet order accuracy goals requirements?
- Does the alternative meet the required packaging standards and that of your customers?
- Is the system flexible and scalable?
- What are the risks associated with deploying such a system?
Source : http://www.OPSdesign.com
As I promised in my previous posting I would now like to go through an approach on transportation cross docking in Dynamics AX. This article is meant for experienced Dynamics AX professionals that have deep knowledge both functional and technical to Dynamics Ax, and is a follow up to the last two articles on Cross docking (See Cross docking I (one) and Cross docking II (two))
First a small reminder what transportation cross docking is. Transportation cross docking is used in distribution scenarios, where you have pure cross docking services. The cross docking facilities are often not the legal owner of the goods. The following figure shows the supply flow.
Here the cross docking warehouse is a pure service provider and do only push forward the goods from received from the vendor and internally transport the goods to the correct outbound dock. The warehouse A is not the cost owner of the goods, and it prefers pallets or cartons. At the distribution warehouse B, C the goods are properly received. Some are placed into the warehouse, but some is cross docked again to the outbound dock.
So what do we need to achieve this in Dynamics AX? As far I have seen it is possible, but will require many manual processes. Here an extension to dynamics AX is required. The first steps are to identify the main concepts needed.
Inbound logistics
I would often describe the inbound freight as a trailer or container that delivers goods to a destination or a HUB. If you are using third party bulk transportation, then the cargo is the entity that communication to the carrier is overall based on. The inbound cargo does not have any directly information of the contents, cross docking information, but contains volumetric information, status and delivery time information. Like when it is planned to ship from the vendor/source hub, and when it is planned to arrive to the warehouse/destination hub. There are some industry standards that are commonly accepted, and that is the Cargo 2000 standard, that contains all needed milestones statuses for a carrier. Getting insight into these milestones is vital to be able to plan forward in the supply chain and to be able to plan cross docking. The milestones should be stored as transactions related to the inbound freight to track the goods. Another register called Yard movements should keep track of the goods/trailer/container as it is received at the yard, and scheduled for receive.
Inbound cargo is the first required concept for cross docking, and standard Dynamics AX do not have this term, but in the To-Increase WM&D solution, the Inbound cargo screen looks like this in AX 2009, together with the cargo 2000 milestone statuses:

When receiving goods that should be cross docked, the goods will be directed to the outbound dock, and associated with the right transportation route(See outbound logistics later for a description).
SSCC(Serial Shipping Container Code)
The next requirement is a unique identifier for the goods arriving. This is very often required to be able to handle the incoming goods. With handling we mean being able to plan and execute the needed steps to cross dock. Without a unique identifier this becomes very difficult. What exists in standard AX is the concept “Pallet”. But in AX the pallet is just an identifier, and do not contain any more information than the identifier and the location it is placed. The content of the pallet can be seen as the “On-hand” overview or the transactions related to the pallet.
But in transportation cross docking the warehouse performing the cross docking services do not necessarily have any insight into the purchase order, sales orders or inventory transactions. Another concept is required to support a transportation cross-docking scenario. In WM&D this is the SSCC (also called Outbound Cargo).
The idea behind the outbound cargo, is that it is an entity that do contain all the required information of the SSCC, without having a transactions associated to the SSCC. This is information like ID, status, carrier, addresses and contents information. But there do not need to be any associated inventory transactions related to it. It could be that the SSCC do have reference information at the final receive warehouse/hub. The information on the SSCC is either received as ASN information, or is registered and labeled at the first receive. Labeling is often very important in these scenarios, and must often be carrier compliant.
In WM&D there are also possible to transfer a pallet ID or license plate to a SSCC, and this is automatically done at picking, packing and shipping.
Outbound logistics
Having a good system for outbound freight is vital, because often the planning done here ‘beats the drum‘ for a large portion of the operations. Quite a large portion of the people in a warehouse has tasks related to the picking packing and shipping. In standard AX, the shipments are the tool used for doing outbound logistics. A shipment is a collection of items that are packed in the same container for transport by, for example, ship, rail, truck, or plane. A shipment includes an entire order, a part of an order, or a consolidation of multiple orders. Based on the contents of the shipment, one or more picking routes, one or more internal transports, or both are created. Output order is a request for picking requirements and is the basis of a shipment. From the shipment you can activate an internal transport, a picking route, or both. The shipment status is based on the lowest denominator of the shipment lines status. The shipment is mainly a tool to create picking routes and pallet transports. But more advanced picking, planning and execution is lacking.
 Figure: standard AX shipment form.
The architecture in standard AX consists of the following tables :
 Figure: standard AX architecture for shipments
As we see here the standard AX do not have any good systems for handling SSCC. It is possible to simulate that the picking routes could “simulate” SSCC, but this leads to many customizations. You may have problems in doing planning and automation, since not much of that exists. Ability to short ship is manually possible, but do require good insight into the transactions. The processes are manual and people must control most of the planning. In WM&D it has been introduced a overlaying system called transportation planning. The transportation planning approach can be visualized like this :
 Figure: How transportation planning is related to standard AX processes.
Here all the functionality of std. AX is used, but a planning system has been created. The shipments and picking routes are then the result of the transportation planning.
A transportation route line is the actual route that the transportation needs to go. It can be several pickup addresses and several delivery addresses on a truck route, and each of this combination will have a transport route line. Each transportation route line will have properties like estimated weight, volume and body length/width. A sequence of transport route lines is the destination addresses.
A transport route is in this defined as a planned transportation. The transportation is most often related to a mode of delivery. The transport route has some physical limitations like max payload weight, max volume, max cargo body length/width. The transport route is the “header” of a set of transportation route lines, and is most often represented as a truck or container.
 Picture : Transport route and transportation route lines
 Picture : Transport route visualized to Google maps. Driving sequence is the numbers on each stop. Truck loading sequence is the reverse of the driving sequence.
The idea here is that all the required output orders will be associated to a transportation route line. These lines can then be planned, either internally in WM&D/AX or in an external route planning tool (or even at the freight forwarder). Then the optimal route can be built, and this is the transportation route. Each line is therefore associated to a transport route.
This gives the possibility to do multisite distribution scenarios with cross-docking capabilities:
 Figure : Warehouse D can be set up as a cross-docking warehouse, where items are received from other warehouses or from vendors.
The process will then go through the following steps:
|
In the previous posting we looked into the theoretical pure Transportation Cross Docking, where there are dedicated cross docking warehouses. But often cross docking is classified into several categories. Cross docking reduces handling costs, operating costs, and the storage of inventory. That’s why this logistics method is used in various industries, e.g. the retail and grocery distribution. Originally cross docking was solely done by moving goods from one truck directly into another. Nowadays cross docking is able to handle larger and more complex operations. Therefore cross docking distribution centers may include highly efficient automation systems for staging, sorting and consolidating inbound materials for shipping. And even a very short term warehousing function might be included. Here are some cross docking types that is often refered to:
Manufacturing Cross Dock Use Cross Docking for the receipt, consolidation, and shipment of a pre-defined quantity of raw materials or component parts, typically from many suppliers, to the product plant.
Distributor Cross Docking Cross Docking is performed on a wide variety of merchandise. Typically it is conducted in operations where various manufacturers, making complementary items, ship their merchandise to a common distributor who assembles the products on a multi=SKU Pallet before delivery to the next level of the supply chain.
Transportation Cross Docking Transportation companies sort and consolidate parcels and pallet loads based on geographic destination.
Retail Cross Docking Products are received at these retailers’ distribution centers, moved across the dock, and married with other products bound for the same store. A few types of display-ready-pallet builds for end-users fit the cross dock profile; items are off-loaded but not put-away, the display ready pallet is built, and then released without being put-away. All would have to transpire within 24 hours.
For now, I would like to focus on two main cross docking methods.
Cross Docking I (Transportation Cross Docking) – This process consolidates inbound products from different vendors into a mixed product pallet for the same store, which is delivered to the customer when the final item is received. Logistics companies then deliver the goods to the respective stores. In this scenario the crossdocking warehouse can be a pure provider of cross-docking services. If we compare this to Dynamics Ax, it means that there are no sales orders, purchase orders or inventory transactions. The information on how to cross dock is information either on labels attached to the pallet, or information received as ASN (Advance Shipment Notification)
Cross Docking II
(Distributor Cross Docking) – This process combines shipments from a number of different carriers. All suppliers receive an overall order summarizing the orders of the individual stores. They then transport the goods as one big delivery to the staging area where the goods are repacked onto pallets with other goods from other carriers for the same store. Logistics companies then deliver the goods to the respective stores. This type of Cross Docking is both an advantage for the customer and the supplier as there is only one order or delivery per day or per week.
A Dynamics AX approach to support cross docking II (Distribution cross docking).
Standard Dynamics AX do not have cross docking support out of the box, but I see several companies is using the direct delivery function to achieve cross docking.
 By doing this, one purchase line can be linked to a sales order line, and the delivery information is transferred from the sales order to the purchase order. The drawback is that there is a “one-to-one” relationship between the receipt transaction and the issue transaction. There is also an issue that the cross is close to 100% manual. (PS! There is an option to specify a shipment reservation sequence that should look for items in the receiving dock, but this is not a pre determent cross docking ).
But in the real world we see the need of a many-to-many relationship. One receive, should be cross docked to several sales orders, meaning that you may receive a large quantity from a purchase order, and it will fulfill many different sales order to different customers. Often it is even not customers, it could be transfer orders to other warehouses, or retail stores classified as warehouses.
Standard AX do have “traces” of solving this. It is called inventory marking.
Here you do have a many-to-many relation between transactions. It is even documented on the inventory transactions as shown here:
Here the Lot-ID points to the Reference Lot on the inventory transaction. So by doing some manipulation on the inventory marking we can make Dynamics AX keep references between issues and receipts. And this is also something that can be the origin to a cross docking II scenario.
But there is a few more things that needs to be in place to make the cross docking efficient. The first thing is to an efficient way of transporting goods from the receipt dock to staging area/shipping docks. But the transportation system must also support transport to all kinds of areas in the warehouse, like buffer location, picking location, outbound docks or to automated warehouse solutions. This can be visualized like this:
Standard AX do have a pallet transportation logics, even though the looks of it could be improved;
Here the user select the pallet ID, and starts the transport. Arriving to the destination location, the user completes the transport. This screen does the job, but the for a warehouse worker on a forklift, it is difficult to use. A forklift operator wants to use barcodes and/or touch sensitive screens. The other negative element is related to that it only supports full pallets. In a real world scenario we often see that transports are needed on cartons or even on items that do not have a unique identifier. In the To-Increase Warehouse Management & distribution, this transportation system has been extended to support transport on both pallet and carton license plates(also called SSCC), and also transport of goods without having a identifier;
When a good way of identifying goods, and a good transportation method is in place, that it is possible to do cross docking efficiently. As shown in the figure below, the cross docking is then processed in the same way as any other transport:
The screen above is the receive transactions where a single purchase line has been split to 10 inbound transports, where the first is cross docked to picking area, while the others are received into the warehouse. In a cross docking scenario the destination location would be an outbound dock, and the name of the customer would also be visible. To-Increase WM&D also support the ability to create the license plates, and to create the correct labeling for the goods to be cross docked and to the correct customer.
So to conclude in how to make an efficient cross docking with dynamics AX you need:
- Build a framework on top of inventory marking to mark how cross docking shoul happen, and that works even when you have a long supply chain.(Going through several warehouses before being shipped out)
- Create a receiving system that allows you to receive ASN and the goods, control the inbound transport.
- Modify the transportation system to support more scenarios(Pallets, Cartons and items)
- Create an efficient system that can be used on forklifts and RF/PDA
- Create a label integration to label the goods.
- Create an efficient outbound registration system.
My advice is…. Don’t try this. A better solution is to look to proven ISV-solutions that focus on this, and my advice is off course To-Increase Warehouse Management & Distribution.
In my next posting I will look deeper into how to implement cross docking I (transportation cross docking).
Crossdocks are high speed warehouses. If an arriving item has already been requested by a customer there is no need to store it as anticipation inventory; instead, the item can move directly from receiving to shipping, without intermediate storage and retrieval. Thus the item can move much more quickly through the facility and the most costly part of warehouse labor can be avoided.
In a high-volume crossdock the turnover times may be measured in hours. To support this velocity of movement, a crossdock may be nothing more than a slab of concrete with a roof and walls punctuated with doors for trailers. Freight is pulled off arriving trailers, sorted and loaded onto departing trailers without intermediate storage.
There is little or no storage provided in a crossdock because items do not stay long enough; but there is generally a lot of material-handling equipment, such as forklifts and pallet jacks, to move freight. Labor is frequently the main cost and it is devoted to unloading incoming trailers, moving the freight to the appropriate outgoing trailers, and loading. Consequently, the issues within a crossdock are those of material-handling and product flow rather than location and retrieval.
Why crossdock?
The biggest reason to have a crossdock is to reduce transportation costs.
This can be achieved by consolidating multiple shipments so that full truck loads can be sent. The Home Depot is a major retailer and the largest user of Less-than-Truck-Load (LTL) shipping in North America. (LTL means sending shipments that do not fill a trailer and so are not economical to send by themselves. Instead, an LTL freight company consolidates many such shipments and so achieves efficiencies.) At the present writing, LTL costs about twice the cost of Truck Load (TL) shipping, so there is a strong incentive to fill trailers. The Home Depot has begun doing this by having vendors ship full trailers to its crossdock. (The trailers are full because they hold product for many stores.) At the crossdock the product is sorted out for individual stores and consolidated with product from other vendors bound for the same store. The result is that each store has enough freight that it or it and a few close neighbors generate a full truck load from the crossdock. The result can be considerable savings.
Additional benefits include less inventory (because all product flows right through) and less labor (because product does not have to be put away and later retrieved).
Operations
Most crossdocking freight terminals are laid out as long, narrow warehouses with doors around the perimeter.
Figure : View from above of a typical high-volume crossdock, which receives freight, sorts, and disgorges it. Each door is devoted to either arriving trailers, which are unloaded, or to departing trailers, which are loaded. Ideally, freight should flow directly across the dock rather than along its length.
A typical terminal, where the small shaded rectangles represent incoming trailers with freight to be unloaded, and small clear rectangles represent (empty) outgoing trailers. Terminals range in size from fewer than 10 doors to more than 500 doors.
Inside a terminal, a variety of material handling methods is used to transport freight. Forklifts and palletjacks carry heavy or bulky items, and carts transport smaller items. In addition, large terminals may have draglines, which circulate carts around the inside perimeter of the dock.
There are two types of doors in a terminal: receiving, or strip, doors, where full trailers are parked to be unloaded, and shipping, or stack, doors, where empty trailers are put to collect freight for specific destinations. Once established, the designations of these doors do not change, although the trailers parked at them will. A shipping door always receives freight for the same destination. A receiving door may be occupied by any incoming trailer, regardless of its origin or contents.
Arriving trucks may deliver their trailers directly to an unoccupied receiving door; or, if none is available, they may place them in a queue. After the trailer is backed into a receiving door, a worker unloads the freight. After unloading items of a shipment onto a cart, the worker walks to the destination trailer and loads the items into that trailer; or he places the cart on the dragline, if the terminal is so equipped. To handle pallet loads, the worker uses a pallet jack, or hails a forklift driver, or finds a forklift and delivers the load himself.
After a trailer has been completely stripped, a driver replaces it with another incoming trailer from the queue of trailers waiting to be stripped. After an outgoing trailer has been filled, a driver replaces it with an empty trailer to be filled with freight for the same destination.
Freight flow
The patterns of freight flow within a terminal—and therefore the work—are determined by:
Layout
by which we mean the specification of doors as either receiving or shipping doors and the assignment of destinations to the shipping doors.
Geometry
The shape of a terminal determines the travel distances between doors and the susceptibility to congestion. (For example, narrow docks tend to be more congested because workers have less room to manoeuver.)
Material handling systems
For example, pallet jacks are slower than forklifts, but they may be more available; draglines reduce walking time, but can impede forklift travel.
Freight mix
For example, terminals having a higher mix of pallet freight require more forklift travel than those receiving a majority of carton freight.
Scheduling In real time, the dock supervisor determines freight flow patterns by assigning incoming trailers to receiving doors.
Changing the geometry or material handling systems of a terminal is expensive; changing the freight mix is a marketing decision with implications outside the terminal. The two remaining ways to take work out of the system—change the layout or change the scheduling—are inexpensive. In particular, the layout can be changed simply by changing the labels on the doors of the crossdock.
There are two kinds of doors on a typical crossdock: Those reserved for outgoing trailers (for example, the “Miami trailer”) and those reserved for incoming trailers. The outbound doors are reserved for specific destinations but the incoming doors are not so specific and may be used by any incoming trailer (because, while departures are scheduled to specific destinations, the terminal does not have full control over arrivals).
Congestion
As more freight flows across a dock, congestion increases, which interferes with the flow. There are several distinct types of congestion on a crossdock:
Competition for floor space: Freight may be docked outside a receiving door if, for example, it consists of many unpalletized cartons going to the same shipping door. Then there is an incentive to accumulate it all so that fewer carts must travel to the destination door. On the other hand, freight is very likely to be docked outside a shipping door while the loader figures out how to pack the trailer tightly. When several nearby doors compete for space to dock freight, some invariably interferes with other traffic. At the very least, it takes longer for a worker to manoeveur through the docked freight.
The effects of docked freight are most severe near the inside corners of the dock, where there is less space per door, as shown in this figure.
Figure: There is less floor space per door at outside corners and therefore more likely to be congestion that retards movement of freight.
The need to dock freight suggests that busy outgoing trailers be parked away from the corners of the dock.
Interference among fork lifts: Despite the intention of moving freight simply “across the dock”, most doors will be to the left or right of a door with an incoming trailer and so a significant amount of freight must travel along the length of the dock. Most crossdocks set up two forklift “highways”, one along each long side of the dock. (It is a good idea to set up two so that, when one is blocked, some freight can still flow.) However, the flow of forklifts back and forth along the length of the dock may be interrupted by forklifts making left hand turns into doors with outgoing trailers. This effect can be reduced by parking busy outgoing trailers away from the very middle of the dock (which is also the most convenient location). Note that this works opposite to convenience, which tends to push busy outgoing doors towards the middle of the dock.
Competition for drag line capacity: Each door receiving arriving trailers will need empty carts from the dragline and, after loading a cart, will need empty cart positions on the dragline. This means that there will be diminished dragline capacity downstream of this door. If the door is far from a busy outgoing door then the region of diminished capacity can be large. This creates an incentive to intersperse incoming doors with outgoing doors. In particular, this suggests that current practice, which is to create large banks of incoming doors, reduces the capacity of the dragline.
Design
The first decision in designing a crossdock is “how many doors?”.
Generally doors are devoted to one of two types of trailers:
- Incoming, from which freight must be removed; and
- Outgoing, in which freight must be loaded
It is easier to unload than to load. A loader must try to get a tight pack and so may have to dock freight and this double-handling slows him down. A good rule of thumb is that it takes twice as much work to load a trailer as to unload one.
To achieve frictionless flow, the capacity for flowing freight into the dock must be balanced with the capacity to flow freight out of the dock. Accordingly, one should plan to have twice as many outgoing doors as incoming doors. Alternatively, one can balance the rates of flow by assignment or workers. For example, if there are equal numbers of incoming and outgoing doors, balance can be achieved by assigning twice as many workers to load. Note, however, that crossdocks with many doors are generally less efficient than crossdocks with fewer doors. The reasons are as follows. A door can only have a few near neighbors on a dock and so a dock with more doors means that each door is likely to have few more near neighbors but many more distant neighbors. This means that in general freight must move farther across a large dock. Consequently, labor costs are generally higher at larger docks.
An additional factor is that on larger docks more freight flows past the central doors, which are the most important because they tend to be close to many doors. In fact, the total flow of freight past a centrally-located door tends to be proportional to the square of the total number of doors. Therefore a dock with twice the doors tends to have 4 times the congestion in front of its central doors, which diminishes their value.
This follows from the following simple model: Imagine a rectilinear dock as a line with 2n doors (numbered from left to right), and assume that equal amounts of freight move between every pair of doors. Then the flow into any door is of intensity O(n). But the total flow passing the area between door i and i + 1 is i(2n – i), which means that the greatest total flow passes by the middle of the dock, door n, past which flows O(n2) units. But these central doors are exactly those that are nearest to most other doors and therefore are the best locations! Thus, as a dock design grows in length, the lengthwise traffic past the central doors increases rapidly while traffic directly across the dock remains unchanged. Increased traffic means congestion, which helps explain why docks can lose their efficiency as they grow. There are few docks larger than about 200 doors. Most are 80–120 doors long.
Do not forget to allow enough parking space in the yard for two trailers for every door. This means that for each origin or destination you can have a trailer at the door plus one full and one empty in the yard. This helps you handle surges in freight flow.
Geometry What is a good shape for a crossdock? In general, one wants to enable efficient flow of freight from incoming trailers to outgoing trailers.
Typically, a crossdock is a long rectangle, with doors for trailers around it. The capacity of a dock is increased if it has many doors, but without being too close together so that trailers (outside) or freight (inside) interfere with one another.
Figure : A typical crossdock is built in the shape of the letter I (actually, an elongated rectangle), so that freight can flow across from incoming trailers to outgoing trailers.
A typical dock, such as illustrated in the picture, is generally around 120 feet wide (36.6 meters). This is to allow freight to be staged on the floor. A standard (large) trailer is 48 or 53 feet long (14.6 or 16.2 meters) and a “pup” is 28 feet long (8.5 meters); all are 9 feet wide (2.7 meters). The width of the dock should include enough space for the trailer on each side of the dock to stage its freight (about 100 feet total, or 30.8 meters) plus allow space for travel along the length of the dock (for example, two aisles, each 10 feet wide, or about 3.0 meters). We have seen docks as narrow as 80 feet (24.4 meters), but this is practical only when it is possible to avoid staging most freight, such as when the material is palletized and also easily stackable and may be loaded in any order. If a dock is much wider than this, it just adds to the travel time to move the product from incoming trailer to outgoing trailer.
A dock does not have to be shaped like the letter I. For example, shapes of an L, U, T, and H. But every corner in a dock reduces effective capacity:
Crossdocks have been built in a variety of shapes. Clockwise from upper left: An L-shaped terminal of Yellow Transport; a U-shaped terminal of Consolidated Freightways; a T-shaped terminal of American Freightways; an H-shaped terminal of Central Freight
On the outside of a corner you lose floor space per door on which to dock freight.
- This increases congestion on the dock, which interferes with the flow of freight.
- On the inside of a corner, you lose door positions because trailers will interfere with each other in the yard. Because doors are lost, the dock must be longer to accommodate a given number of doors, which means that on average freight will have to travel farther to cross the dock. Thus, for example, freight has to travel farther to cross an H-shaped dock, with four inside corners, than to cross an I shaped dock. (Because the door positions will be lost anyway, inside corners are a good place to locate administrative spaces or hazardous materials storage.)
It is hard to make generalizations independent of specific bills of lading; but in general an L-shaped crossdock is inferior: It incurs the costs of one inside and one outside corner but without getting anything in return. The result is that freight must travel farther because the dock must be longer from end to end to make up for lost doors at the inside corner. Furthermore, there is congestion at the outside corner. The same observations hold even more strongly for a U-shaped dock.
An X-shaped or a T-shaped dock also incur corner costs but they have a compensating benefit: The longest distance from door-to-door is less than that for an I-shaped or L-shaped dock with the same number of doors.
Trailer management
One can reduce labor costs in a crossdocking freight terminal by parking incoming and outgoing trailers so that freight can be efficiently moved across the dock. For example, if much of the freight flowing through the terminal is bound for Miami, the Miami trailers should probably be parked in a convenient location. The challenge is to formalize the notion of “convenient”; then labor-reducing door assignments can be made with optimization models based on the geometry of the terminal, the material handling systems within, and the mix of freight passing through.
References : Copyright 1998–2011 John J. BARTHOLDI, III and Steven T. HACKMAN. All rights reserved. This material may be freely copied for educational purposes—but not for resale—as long as the authors’ names and the copyright notice appear clearly on the copies. Corresponding author: john.bartholdi@gatech.edu
Warehouses may be categorized by type, which is primarily defined by the customers they serve. Here are some of the more important distinctions:
A retail distribution center
typically supplies product to retail stores, such as Wal-Mart or Target. The immediate customer of the distribution center is a retail store, which is likely to be a regular or even captive customer, receiving shipments on regularly scheduled days. A typical order might comprise hundreds or thousands of items; and because the distribution center might serve hundreds of stores, the flow of product is huge. The suite of products changes with customer tastes and marketing plans; but because the orders are typically known a day or more in advance, it is possible to plan ahead. Some product may be pushed from the distribution center to the stores, especially in support of marketing campaigns.
A service parts distribution center
is among the most challenging of facilities to manage. They hold spare parts for expensive capital equipment, such as automobiles, airplanes, computer systems, or medical equipment. Consequently, one facility may represent a huge investment in inventory: tens or even hundreds of thousands of parts, some very expensive. (A typical automobile contains almost 10,000 parts.) Because of the large number of parts, total activity in the DC may be statistically predictable, but the demand for any particular part is relatively small and therefore hard to predict. This means that the variance of demand can be large and so relatively large quantities of safety stock must be held, especially since there can be usually long lead times to replenish parts to the warehouse. Indeed, sometimes there is as much safety stock as cycle stock, and so, in aggregate, these skus require much space. This in turn increases travel distances and makes order-picking less efficient.
A typical service parts warehouse manages two distinct order streams: stock orders, by which dealers replenish their shelves; and emergency orders, in which an equipment owner or independent repair shop urgently requires a few special parts to repair a broken piece of capital equipment. Stock orders tend to be large and fairly predictable replenishments of popular consumables, while emergency orders are typically small (two to three pick-lines), unpredictable, and urgent, because expensive capital equipment is likely waiting for repair. Emergency orders are typically for items that are ordered infrequently (otherwise they could have been provided by the dealer from stock inventory). Such orders—a few, slow-moving items that must be picked immediately—are relatively expensive to handle. Worse, customers ordering for repair might order before they are absolutely sure which parts need replacement; and so there can be a significant percentage of returns to be handled at the warehouse.
For most product in a service parts warehouse there are not sufficiently reliable patterns of movement to justify special processes, but one can layout stock to be more space efficient by storing similar sizes together, thereby reducing travel. Furthermore, one can hedge chances of having to travel long distances. For example, it can be advantageous, especially for emergency orders, to store products together that are likely to be ordered together.
Another complication is that the life cycle of a service part is unusual, with three stages of product life, as shown in the next Figure.
Early failures are generally due to manufacturing imperfections; mid-life failures are generally due to random events that stress the part beyond its tolerance; and end-of-life failures are due to expected wearing out of the product. Demand for product generally reflects this pattern, and creates challenges in the warehouse. For example, there is little time to ramp up availability of new product at the start of its life cycle. Also, parts are more frequently requested at the end of the product life cycle, and so it is easy for the warehouse to be stuck with obsolete merchandise. Finally, it may be necessary to relocate product as its popularity changes.
A catalog fulfillment or e-commerce distribution center
typically receives small orders from individuals by phone, fax, or the Internet. Orders are typically small, for only 1–3 items, but there may be many such orders, and they are to be filled and shipped immediately after receipt. Because customer orders require instant response, such distributors typically try to shape demand by offering special prices for ordering at certain times or in certain quantities or for accepting more variable delivery dates.
A 3PL warehouse
is one to which a company might outsource its warehousing operations. The 3PL provider might service multiple customers from one facility, thereby gaining economies of scale or complementary seasons that the customers would be unable to achieve on their own. 3PL facilities may also be contracted as overflow facilities to handle surges in product flow.
A perishables warehouse
may handle food, fresh flowers, vaccines, or other product requiring refrigeration to protect its very short shelf life. They are typically one link in an extended cold chain, along which perishable product is rushed to the consumer. Such DCs are distinctive in that product dwells within for very short times, frequently only hours. Also, there is a great emphasis on using space effectively because, with refrigeration, it is so expensive. They face many challenges in inventory management, including requirements to ship product according to FIFO (First-In-First-Out) or FEFO (First-Expired-First-Out). Also, there are typically many restrictions on how product is handled. For example, chicken cannot be stacked on top of anything else, to protect against juices dripping onto product below and contaminating it. Finally, appropriate temperatures must be maintained and this can be different for different kind of products. A typical food DC operates separate areas for ambient temperatures, chilled (around 2 degrees C, 35 degrees F), and frozen product (-18 degrees C, around 0 degrees F). To protect stored product, it is important to avoid bringing in anything warmer. This type of warehouse will become more common as China, India, Brazil, and other rapidly industrializing countries build a middle class, which will increasingly want fresh fruit, vegetables, meat, and dairy.
While there are many types of warehouses in the supply chain, one of the main reminders is that there is a systematic way to think about a warehouse system regardless of the industry in which it operates.
What we need to realize is that the selection of equipment and the organization of material flow are largely determined by :
- Inventory characteristics, such as the number of products, their sizes, and turn rates;
- Throughput and service requirements, including the number of lines and orders shipped per day;
- The footprint of the building and capital cost of equipment;
- The cost of labor.
We also see that there is a regional difference in how to organize warehouse operations. Here is a brief survey:
North America
North America is driven by mass consumption. Think Wal-Mart. This enables huge economies of scale and, indeed, the trend has been for ever larger distribution centers and ever accelerating rates of product flow. As telecommunications enables better coordination along the supply chain, the uniformity of market and of distribution infrastructure allows fewer, more centralized and therefore larger distribution centers.
The Amazon.com distribution center shown in the following figure is typical:
One level, with conveyors and sortation equipment but little other significant automation. Such warehouses are generally built in the countryside surrounding major metropolitan areas, so that land is cheap but there is still ready access to large markets.
The fairly high costs of labor are held down somewhat by constant immigration into the US and Canada.
Warehouses in North America are coordinated by increasingly sophisticated warehouse management systems and so very rich data sets are available with which to evaluate and refine performance.
East Asia
Business in Asia has traditionally been based on personal relationships and less on computational models. Because of this tradition, data is not robust and not widely available; consequently the opportunities to improve operations by science are not fully developed at present.
In general, the most active economic areas are separated by lots of water, which means lots of product conveyed by air (for high-value or time-sensitive products) or ship (for bulky items or commodities). For both air and sea cargo, the large fixed costs increase incentives to consolidate freight. Consequently one expects to see the emergence of strong regional hubs, such as Singapore and Hong Kong, to support this consolidation.
India
India, like many developing countries, has both inexpensive land and low labor costs. Capital costs are relatively high in relation to the cost of labor and so there is less pressure to install specialized storage, even pallet rack. And because labor costs are low there is less incentive to increase efficiency. For example, it is not an attractive proposition to reduce labor costs by picking from flow rack: The labor savings cannot justify the cost of the rack or the forklift trucks.
In addition, warehouses in India distribute mainly to the local economy and so supply a market that is not wealthy. Consequently, the SKU’s are not likely to be high cost items and so there is not much savings available from reducing inventories by precise timing. Consequently information technologies cannot generate much savings.
Finally, inefficiencies in transport make India in effect a collection of smaller markets. These inefficiencies include the physical, such as roads in less-than-ideal condition, as well as the administrative. For example, each state within India levies customs duties on freight transported across the border. This slows interstate commerce and increases the expense. Such factors increase the costs of transportation and so favor a strategy of having more, smaller distribution centers rather than fewer, larger ones, where the volume of activity could better justify capital investment. The national government is attempting to revise its tax structure fix these inefficiencies.
 Figure : The relatively low cost of labor, high cost of capital, and artificially small market mean that this warehouse in India may be economically efficient. (Photo courtesy of Rohan Reddy)
India is increasingly becoming a global sourcing hub and so suitable distribution centers are being built in around large ports, such as Mumbai (Bombay). However, land can be expensive there. Caleb Tan of Menlo Worldwide Logistics has observed prices comparable to those of Singapore or Hong Kong. Apparently this is due to a lack of land because of encroachment of slums as more and more people migrate from the countryside to economically vibrant areas.
China
A distinctive feature of the logistics scene in China is the seemingly boundless supply of very low cost of labor together with relatively inexpensive land. Consequently warehouses tend to be large, low buildings as in North America; but with some striking differences. For example, it is not unusual as of this writing to find a warehouse of 250,000 square feet with a single fork lift truck. The reason is that equipment is expensive but labor is cheap.
 Figure : In the US warehouse on the left, cartons of beer have been palletized because labor is expensive compared to capital. The reduction in labor is worth the expense of a forklift plus the additional storage space. In the Chinese warehouse on the right, cartons have been stacked by hand and must be unstacked by hand; but labor is cheap and capital is expensive.
Despite cheap labor, China does have some capital-intensive warehouses, with the latest information technology and storage equipment. Such warehouses are most likely devoted to the distribution of high-value goods for export. Because such goods, such as consumer electronics, have high-value and short life-cycle, the warehouses can justify their equipment by substantial reductions in inventory costs.
The very different costs in the US and China sometimes leads to behavior that makes sense locally but may make the supply chain inefficient. For example, The Home Depot receives some Chinese-built product at its Import Distribution Center in Savannah, Georgia, USA. The shipping department in the warehouse in China de-palletizes freight in order to pack each trailer as tightly as possible for the drive to the sea port. Thus an expenditure of relatively cheap labor will reduce the relatively significant costs of equipment and transportation. But this means the product arrives in the US as loose cartons in containers and so The Home Depot must re-palletize the cartons before storage in deep, drive-in pallet rack. And most of it will, shortly after, be de-palletized once more when it is picked as cartons for shipment to stores.
Singapore, Hong Kong, Japan
Some economic powers such as Singapore, Japan, and Hong Kong suffer from limited space so land is much more expensive than elsewhere. Consequently, many of the warehouses are high-rise, such as shown here:
Figure :Multi-story warehouses are common in Singapore, Hong Kong, and Japan where land is expensive.
In addition, as first-world economies, labor in these places is expensive and so warehouses here are more likely to be automated. Freight elevators are likely to be bottlenecks to material flow in these facilities.
Space constraints have led to an interesting type of warehouse in Hong Kong and in Singapore: A multi-floor facility with no automation or elevators, but, instead, a spiral truck ramp so that trailers may be docked at any floor
 Figure : Multi-story warehouse with no automation but accessibility provided by a spiral truck ramp.
In effect, each floor becomes a ground floor—but the cost is that significant land area, determined in part by the turning radius of a truck, is lost to the ramp and unavailable for storage. That storage space must be reclaimed up above.
This design is a clever and efficient way of using space if each floor is occupied by an independent tenant. But one must be careful if some tenant occupies multiple floors for then it may become necessary to shuttle trucks among floors. For example, a multi-story warehouse with spiral ramp would be unsuitable as a local distribution center: Trailers departing with small shipments for many customers must be loaded in reverse sequence of delivery to avoid double-handling. But since the load may not match the layout of product amongst the floors, this could require much shuttling of the trailer among floors to load.
Similarly, this might be an inefficient warehouse in which to receive shipments of diverse items that may be stored on different floors: Because rear-entry trailers restrict the sequence in which freight can be accessed, a trailer may have to shuttle among the floors to deliver all the freight to the appropriate places. Alternatively, the trailer would have to be loaded to match the allocation of product among floors at the warehouse. In either case, extra work is required.
Central and South America
This is a region of developing markets that are separated by geography such as the Amazonian rain forest and the Andes mountains. Consequently, markets tend to be relatively small and inappropriate for significant capital investment in warehouses.
Data may not be available or may not be transmitted to supply chain partners. In part this is because there has not been a strong, reliable stock market and so wealth has generally been invested in family businesses, which are less inclined to share data.
Labor costs are relatively low, but some segments of the workforce enjoy strong political protections, which results in labor inflexibility. Consequently, while labor can be cheap, it can be hard to shrink or re-deploy a workforce. Most of labor is devoted to handling small quantities, because retail stores are small and customers purchase tiny amounts daily.
Space is the main concern. Infrastructure is not well-developed and so, to reduce travel on bad roads, warehouses must locate close to the customer. But customers are concentrated in a few, very large cities such as Mexico City, Sao Paolo, and Lima, which are congested and where space is expensive.
Most warehouses in this region hold goods for domestic distribution. Because markets are not highly developed, inventory tends to be of less expensive goods and so the costs of moving inventory slowly are relatively low. (In contrast, China has many distribution centers supporting export of high-value goods, such as consumer electronics. The high cost of holding such inventory, justifies investment in facilities that enable rapid movement of product. This also holds for Mexico, which can get product quickly to market in the US and so able to justify advanced distribution centers.)
The following photograph reflects the low labor costs relative to the costs of capital in this region.
 Figure: A ladder is much cheaper than a person-aboard truck, though much slower. (Note the product stored as loose cartons.)
Europe
Warehouses in Europe, especially in Germany and France, are shaped by the relatively high labor costs and inflexibility of the work force. These facts push designers to find engineering solutions rather than social solutions to logistics challenges. For example, there is a greater inclination to use automation than in comparable facilities in North America.
In the past, the economies of Europe were separate. More recently the economies are integrating into a common market, which will create economies of scale, which will likely lead to larger warehouses. However, urban areas, many of which have grown out of ancient towns, will still present challenges to the efficient flow of product. All this is reflected in Figure,
 Figure: A highly automated distribution center in Germany. (Photo courtesy of Kai Wittek)
which shows a distribution center of a major drugstore chain in Germany. The multi-story portion of the building, visible in the background, houses a high-rise automated storage-and-retrieval system. This is not so much to conserve space as to reduce labor costs. (Unlike the Singapore warehouses, this facility is tall only where the AS/RS is installed.)
According to the Rossman web page, the AS/RS is 30 meters high, the aisles are 127 meters long and the facility provides 14,000 pallet positions. The delivery trucks in the foreground are relatively small, at least compared to the 48-foot trailers common in North America. The small trucks are necessary to deliver to stores in the centers of cities, the ground plans of which may have been laid out centuries ago and cannot accommodate large trucks. But the warehouse is large, reflecting the extent of the market it serves.
References : Copyright 1998–2011 John J. BARTHOLDI, III and Steven T. HACKMAN. All rights reserved. This material may be freely copied for educational purposes—but not for resale—as long as the authors’ names and the copyright notice appear clearly on the copies. Corresponding author: john.bartholdi@gatech.edu
The company behind the inventory II
Inventory II is an add-on module to Microsoft Dynamics AX, that focuses on improving and extending inventory management. Before I look deep into the product, I wanted to take a look at the developers of the module. The company behind the Inventory II is ‘FSB‘. FSB is the first letters of Flemming, Søren and Benny. For us, that have been with the Dynamics AX from the beginning, will recognize these developers, because they are the founding fathers of most of the costing, supply chain and production code in Dynamics AX. They worked closely together with Erik Damgaard to create to Axapta(That later became Dynamics AX). Much of the current source code of Dynamics AX originates from ‘FSB‘-team. This tells me that the Inventory II is made by developers with probably the best knowledge of how the inventory architecture in Dynamics AX is build up.
So what is it all about ?
First we need to understand how standard Microsoft Dynamics AX is maintaining on-hand and how the inventory values are tracked. In AX all transactions are stored in a table called inventTrans. Each time records are inserted, updated or deleted, these changes will update another table called InventSum. As the name suggests; InventSum contains a summary of the onhand per dimension(like color, size, location, warehouse, pallet etc). The data model can be visualized like this :
Normally this model works very fine, but there are some drawbacks in the model.
Very large joins
Since the table InventSum and InventDim table can be VERY large, I have often seen performance problems when these two tables are joined in queries. Often from a financial perspective you may want to get the inventory value in total per warehouse. At a customer site where they have approx. 13000 SKU’s and generate approx. 50.000 inventory transactions a day, they have around 60 million inventory transactions in total. What trying to get a total inventory value, the reports often needed to run for many hours. It seems, when you need to join the two very large tables, the performance of SQL drops drastically.
Reporting on historical values
Another issue is how to report inventory sum and values on a specific date. Like “1/1/2010”. I have looked deep into this, and see that the way std. AX is working, is to take the current InventSum, and “sum-reverse” inventory transactions posted between now and the wanted reporting date. If you have many transactions, you will see that this quickly will take a lot of time to make an overall reporting.
Database locking
At a customer site where we implemented Axapta 3.0, we had 18 packing stations, that packingslip and invoice updated sales orders all day long. The average size of the sales orders was 8 lines. What we very often experienced, was “blocking locks” at the packing stations when they did the postings. The reason was that when the packingstations invoice updated the orders, Axapta also did a update on the InventSum to reflect this posting. If this also happened on another packingstations, it very often could lead to a blocking lock, where the two packingstation was waiting for each other to complete. At that time we concluded that the main reason for this was the “UPDATE INVENTSUM” that std Axapta made. This process has been improved in AX 40, and AX 2009, but the update processes still there, that could lead to blocking locks.
Inventory value
With std. AX there is a need to run a periodic process called “inventory closing”. The inventory closing is the process of settling receipt cost values with the issue cost values. To say it simple; If the financial on-hand quantity is Zero, the financial value should also be zero. This is actually a great feature, because it allows you to sell the items before you receive the vendor invoice, and the real cost from the vendor invoice can be propagated to the respective sales orders/ issue transactions. But what we see in practice is that the inventory closing is ran one a month, and then it could take several hours to complete. Also a lot of issues related to this has also been seen, which could result that the inventory values suddenly gets bigger than the US military budgetJ.
Level based reservations / intelligent reservation
For large distributors, reservations are a “must-have”. The ability to promise the customers that the order has been reserved almost guarantees that the customer will get the goods in time, and that no other sales order will “steel” the items. But many distribution centers differentiate between buffer and picking locations. In std. AX you could physical reserve the items, but this prevented the users from moving the goods from the buffer area to the pick area, where the items could be picked. The reason for this is that the reservation is “exact”. In Axapta 3.0 this resulted in that we needed to make a system called “virtual on-hand”, to maintain reservations, but still have the opportunity to move the items around. Another important feature I missed was the ability to control the allocation. So that some on hands dimensions are used before others. A scenario for this is if you have an automated warehouse area, and you want to control this area in relation to other area’s.
Inventory II
When we should upgrade the customer to AX 2009, we got to know the FSB, and got trained on the Inventory II product. WOW, did this solve most of our biggest problems. The solution was elegantly small, and easy deploy into the system. The Inventory II was also built into the To-Increase module “Warehouse Management & Distribution”. The architecture is a bit different, and can be visualized like this :
The complexity of on-hand has been replaced by a single table, called ImTrans. This system uses a ‘insert-approach’, meaning that there do not happen any SQL-“update” statements on any of the records. This way it removes any “blocking locks” and maximizes concurrency in the database when updating the on-hand values. FSB also introduced a system called “Watermark” to keep track of what records are valid for the current on-hand. If we take the process of a sales order going from “On order” to invoiced, the ImTrans would have transactions like this :
Step 1 : First transaction – Sales order line is created with 10 pcs of item V1. Inserted with an issue status of ‘on order’, and the watermark level is ‘W1’
Step 2 : Line is reserved; This results in a “reverse transaction” where the first transaction is eliminated (If you do a select sum() you would only get that 10 pcs is reserved physically)
Step 5 : Then we “jump” forward to the invoice step, and each time the previous statuses are reversed.
So the on-hand transactions are not a single record, but a SUM of the records. The watermark will make sure that you only fetch the latest values when you do reporting. So this solved the issue of the blocking lock when doing postings.
But will this not generate a gigantic table ? The answer is yes, it would, and the heart of the inventory II is therefore a background engine, that will eventually remove ImTrans records that no longer represents any valid data. In inventory II this engine can be visualized like this :
Here there is a parameter for how long the inventory II should keep the records in the intermediate status postings. FSB has also included a monitor for what the inventory II engine is doing :
But the engine does much more. It also do the cost settling, background reservations, compression, issue alerting and posting cost differenced to general ledger.
But for me feature I like the most is the level based reservation(Also called intelligent reservation), where sales order can be reserved on a warehouse at order intake, but not specify location, batch on the reservation. Later in the process when picking route has been created, the reservation can be tighten down to location etc. And at the end when the transaction is picked,(or posted) the final dimensions like pallet ID, serial ID etc is specified.
The nice thing is that the set up for this is dynamic, and is specified on the dimension group an item is related to:
Conclusion
With the experience I have had with Inventory II, I can truly recommend this solution. I would never go ahead to implement a high volume/transaction customer without inventory II, because I have truly felt the pain without it. The support is very good, and help is always near if you need it. The question is how will this change in AX 2012. As far as I have seen and heard, the inventory II features are still needed in AX 2012, and I know that the FSB guy’s are working on an AX 2012 build. I look forward test it out.
Bad managers are often weak on communication – with poor performance on employee relations. This must often be compensated with unnatural hierarchies and “tight lines”. One does not become a better leader by turning a deaf ear.
Leadership is about to listen, analyze signals and to make decisions – whether they are popular or not. But the definitive answer for leadership does not exist. Management is also situation-oriented. The leader must deal with a story, an environment, a culture, individuals, its place in the “life cycle”, the market and much more. Being a good leader, requires expertise in a wide variety of disciplines. Not least, psychology and sociology.
We see many thoughts, theories and concepts related to management. Dear child apparently has many names. No matter what we call field of management, the management is a balancing act that involves many audiences. One should relate to a board, to other management and employees. Yes, let’s call it for internal communications. But one should also relate to external audiences. Be could be customers, potential customers, parters, owners and shareholders, regulators, journalists, and more.
Being a leader is so that one must master many disciplines, one must be both broad and deep. And you have to continuous speeding up and braking down. It is a great achievement to be a good leader.
Modern management is not only about involvement. One must care about people to get them to perform. And the staff must be very much feel they are listened to. The leader must be real – those who only play a role is in fact quickly discovered – and then threw out the door.
I work in IT-industry, and we work in a tremendous pace. Then the leader must also show willingness to change with an equally high speed. If not – it’s over and out.
Among the requirements is that the leader must be involved and receptive – and make their decisions based on a totality of ideas, arguments and values. Then it is important to listen to his subordinates, involving them in decisions and the courage to put the hierarchy aside for the best ideas.
It is also true that the strongest communities often employ the brightest minds. These are people with a commitment and that largely wants to have influence on their everyday life and its development. Modern leaders also attracts the best resources. They both courage and ability to hire the best people. The receptive and dynamic leader will both develop the company, employees and themselves. I believe it is this that gives companies and organizations progress and success.
The smartest leaders treat the employees as enthusiastic, intelligent and independent people. They are involved and they are strong enough to take decisions based on good processes.
Good management requires insight into the people and the courage to get involved, and that is what I feel I’m experiencing as Columbus IT Norway consultant. If you have a bright mind on ERP and Dynamics AX and to want to experience true leadership I encourage you to contact us.
This is a brief rundown of possible benefits of slotting and its impact on several operational factors, from different sources and our own experience.
Some warehouses with few SKUs and trivial order lists may not need slotting at all. The larger and more complex a warehouse becomes, the more slotting will have an impact. Ranges of % in benefits are for typical warehouses, but can vary from 0% – to even more than what is stated. Values are extremely dependent on several interacting aspects of warehousing, most significantly: order profiles, diversity of SKUs, geometry of warehouse, the existing layout and slotting procedure.
Pre-Slotting
Layout:
For warehouses using many different products, mixing several storage systems becomes more cost-effective than using only one type of storage. However, rule-of-thumb systems are difficult to size and results can be far from the optimized solution, with productivity impacts up to 30-40% on replenishments and picking.
The optimal balance between types of racking can be determined using specialized software, evaluating the relative needs for replenishment, picking rates, space, flow-rack cost, etc.
Space Maximization:
Pre-slotting determines the optimal quantities and storage types for products based on their order profiles. This maximizes the warehouse cube, thereby cutting the square footage requirements with possible space savings in the 35% – 43% range.
References:
– Bartholdi and Hackman, Warehouse & Distribution Science 2010
– Avery, Operations and Fulfillment, July 1999
Dynamic Slotting
Typically, static slotting for distance and velocity alone can reduce labor cost by 10%. Further savings of 5% can be achieved by using batch picking and product family grouping. Dynamic slotting uses floating-pick storage spaces, and uses specific-period strategies instead of product life-cycle strategies. Receiving and put-away are directed moves to specific locations. This results in sustained productivity, with measurable savings in operational costs from fixed slotting.
Space Utilization: minimize allocated free space because of adjustable assigned volumes.
Put-Away: Directed put-away reduces guesswork and eliminate errors, and removes the need to search the warehouse for locations.
Replenishment: Synchronizing stock replenishment and space allocation can significantly reduce the number of stockouts, a time-consuming problem for high-throughput distribution centers. A case study showed results of up to 77% less stockouts.
Picking Efficiency:
Results indicate that order fulfillment time can be reduced by 20%. Using an optimal combination of picking policy (good slotting may optimize batch picking strategy); up to 50% in labor savings from traditional strategies can be reached.
Order completion and shipping: reduce management and order completion time, as picking is optimized.
Some Intangibles:
Many aspects of warehouse operations will experience reduced pressure because of smart slotting:
– put-away management
– order picking management
– shipping management
– improvements in key metrics (KPIs): picks per hour, cycle times, inventory turns, order accuracy, order checking.
– enhanced work environment and safety (ex.: high velocity items in safe locations)
– fewer material damages (less distance traveled, less material relocation and handling)
– equipment wear
References:
[Petersen CG, Aase G, Int. J. of Production Economics, 2004]
[Launders, IIE Transactions, August 1996] 37% improvement cited
[Frazelle, 1990] 20-50% improvement in picking time.
[X.He , SP Sethi , J Optim. Appl. 2008ç
[Gagliardi, Ruiz, Renaud, 2008] 77% stockouts
Conclusion:
Slotting has an impact on all of warehouse operations and KPIs: productivity, shipping, inventory, stocking, order cycle, storage. The typical distribution of cost in warehouse operations is [Frazelle, 2002]:
– Order Picking: 50%
– Shipping: 15%
– Receiving: 15%
– Storage: 20%
Adding the savings from all operations, it is a reasonable assumption that dynamic slotting will provide 10 to 30% cost reduction from a baseline operation.
Studies suggest that in a typical warehouse, less than 15% of SKUs are properly slotted. Once fully slotted, most warehouses would save 10 to 30% on operations. For a medium size distribution center with several thousands of SKUs, simulations also show 20% savings in total labor cost. Examples of 100% improvement in both productivity and response time have been reported. Given that planning cost and establishing a slotting strategy is minimal in capital investment and risk, this is a most profitable ROI.
Possible improvement on Warehouse KPIs:
– Picking rate: 20-50%
– Order completion time: 25%
– Storage efficiency: 0-30%
– Equipment usage cost: 25%
– Material damage: 25%
– Space utilization: 5-40%
Some of the most costly processes in the warehouse are picking and pack out process. They also account for the majority of the warehouse operational time- Lets discuss some of the key aspects that should be considered to reduce cost and increase warehouse operations efficiency.
Location planning
Deciding the location for placing the item plays a key role in increasing the handling efficiency. Following factors should be considered while assigning a location for a particular item, number of counts of the item, Item’s volume and weight, sales volume during normal and peak periods of warehouse operations, special handling requirements and if any value added services like kitting etc is required to be done.
Typically products are slotted in the storage mediums like pallet racks, drive in or drive through racks and bins. Once location is designated the next thing would be the numbering and grouping of the locations. Numbering should be done based on the building, zone, level bay facing and aisle. This activity will help in increasing the picking efficiency and reduce the time spent by the pickers searching for products.
Classification
Item’s should be grouped intelligently like fast movers, slow movers and medium movers. One should place the fast moving item’s in the locations which are closest and easier to reach and in a place close to the order fulfillment stations, this will improve the time taken to fulfill an order. Similarly slow movers can be placed in remote slots inside the warehouse as it will not be affecting the average picking time since these are sparingly ordered.
Refill
Internal routines must be developed to replenish the fast moving items in the line locations this will help in reducing the time taken to pick as the pickers will not be going back with zero inventories in the designated locations. Warehouse operations can decide the basis for refill like need based or minimum stock level refill’s which will reduce the labor cost in doing refills.
Storage types
Couple of broader classifications available for storage of products is flow storage and static storage. This contributes a lot in improving the bottom line and reducing the time and labor for doing picking and replenishment’s. The main advantage of flow storage is that the products will be coming to the pickers and they don’t have to go in search of item’s. With the help of modern control systems any warehouses using the conveyors and carousels to bring the products to the place of order fulfillment stations will be able to show a much higher productivity. The capital expenditure done to accomplish this will make a lot of difference in the bottom line of warehouses. This one time expense can be justified if the warehouse experiences a lot of activity and involves a lot of labor for picking and packing.
Source : http://www.infosysblogs.com
| |