Component Flushing Methods in Microsoft Dynamics NAV
I get a quite a few questions related to Component Flushing Methods in Microsoft Dynamics NAV. After looking at the various NAV Forums, I thought a more in depth explanation of this function might be of some help.
First of all, we need to define flushing. The APICS Dictionary defines it as “A set of inventory bookkeeping methods that automatically adjusts computerized inventory records based on a production transaction. Examples of automatic relief methods are backflushing, direct-deduct, and pre-deduct processing.” This concept is quite complex, so I have written a more detailed definition:
Flushing is the process of recording the movement of inventory items from a storage location to Work-in Process (WIP). Work-in-Process here means the production area where the material will be used. There can be three type of flushing:
Forward Flushing (pre-deduct processing)—An automatic flushing type in which the movement of inventory items to WIP is automatically recorded before the Production Order is started or a single Production Order Routing step is started.
Backward Flushing (backflushing)—An automatic flushing type in which the movement of inventory items to WIP is automatically recorded after the Production Order is completed or a single Production Order Routing step is completed.
Manual Flushing (direct-deduct)—The movement of inventory items is recorded to WIP as it happens
If this were not complicated enough, we also have to consider something called Routing Link Codes in Dynamics NAV.
First let’s define routing. I again went to the APICS dictionary to get this: “Information detailing the method of manufacture of a particular item. It includes the operations to be performed, their sequence, the various work centers involved, and the standards for setup and run. In some companies, the routing also includes information on tooling, operator skill levels, inspection operations and testing requirements, and so on.”
Using the screen shots from Dynamics NAV 2013 for a Routing and Bill of Material and Item, we can see that the routing has Routing Link Codes 100 and 300 assigned for Operation 10 and Operation 40 and the Bill of Material has the Routing Link Codes assigned to components on the Bill of Material. The Flushing method is set up on each item card.
Dynamics NAV Routing
Dynamics NAV Production Bill of Material
Dynamics NAV Item Card
Following is how Dynamics NAV handles the timing for each flushing method:
Manual Flushing—A manual flush is performed when the consumption transaction is posted by the user using the Dynamics NAV Consumption Journal or the Production Journal.
Automatic Flush—The table below discusses timing for forward and backward flushing:
| Â | Forward Flush | Backward Flush |
| With Routing Link Codes | The system will automatically deduct the component(s) with the Flushing Method of Forward on the BOM with the associated Routing Link Code when the Individual Routing Step is Started | The system will automatically deduct the component(s) with the Flushing Method of Backward on the BOM with the associated Routing Link Code when the Individual Routing Step is Completed |
| Without Routing Link Codes | The system will automatically deduct all of the components on the BOM with the Flushing Method of Forward when the Production Order is Released | The system will automatically deduct all of the components on the BOM with the Flushing Method of Backward when the Production Order is changed to the status of Finished |
The choice of which flushing method to use is dependent on your situation, but here are some thoughts to keep in mind:
- If you are using Lot or Serial Tracking, automatic flushing is not a choice.
- If the items you actually consume and use in production are typically different from what is in the Bill of Material, automatic flushing is not a choice. This may be particularly true in process manufacturing where the quantity of items consumed may be more or less than what the Bill of Material calls for.
- If your production cycle is long (more than a week), you should consider Routing Link Codes so that consumption can be recorded when the Routing Step is started or completed.
- If your production cycle is short (e.g., one day), you should consider back flushing without Routing Link Codes so that all of the items are consumed when the production order is Finished.
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