Overview: Component Backflushing

Component floor stock items and yield items (negative quantity per) are both processed when a manufacturing order receipt is stocked. The bill of material quantity per and total quantity received to stock are used to calculate the total net quantity required.

If you have a lot of fractional usage, consider using a smaller stocking unit of measure. For example, if you use pounds, consider changing to ounces. Component requirements are rounded up to the next full integer. See Component Picking: Fractional Quantities.

Alternatively, you can create a bill of material component with a zero quantity per. When the stock for this type of item is issued to the floor, it is simply removed from stock. The amount of stock on the floor is not significant for inventory purposes and for these types of items the usage cannot be accurately computed. The cost becomes part of the overhead.

As a rule of thumb early operations that consume commodity types of components are generally set up have the components picked. For example, you stamp parts of steel and the unit of measure is in pounds. You want to compute a manufacturing variance to indicate actual pounds used versus the bill of material calculation.

Later operations that use sub-assemblies typically have more accurate component quantities. In these cases, it is recommended to use the quantity completed and the bill of material quantity per to calculate the usage.

You can move component items to a work center location and then backflush them from that location. This enhances your inventory control in the fact that the warehouse count should always be in that location. If you have components that are lot or serial controlled, you will probably want to pick them manually or ensure that the work center location only has the stock you wish to backflush.

Manufacturing System Options

The picking operation for components can be automated through the use of manufacturing order activity to "pick" components based on the bill of material, reducing the number of transactions. This process requires that the bill of material be highly accurate. No manufacturing variance is created for this type of item. The disadvantage is the built-in differential between what is physically in stock versus what is in process. Extra care must be taken when cycle counting these types of items since components may be consumed by partially completed manufacturing orders. No manufacturing variance is created for this type of item.

Manufacturing system options control how components are backflushed:

  • Process excess/short components
    If you choose one of the options that processes excess/short components when the manufacturing order is stocked, the quantity received to stock is used with the current quantity per assembly to increase/reduce the stock on hand and increase/decrease the quantity picked.

  • Backflush components by operation seq?
    The bill of material can indicate the routing operation sequence at which the component is consumed. When the operation is reported the component is removed from stock and the item is added to the component quantity picked based on the operation completion quantity and the bill of material quantity per assembly.

  • Backflush comps not attached to oper?
    This controls items where components are backflushed if no operation sequence is specified on the bill of material. Selecting this option performs the backflush on the first reported operation and can reduce the number of bill of material components you have to assign routing operations to.

  • Use only inventory in backflush loc?
    When selected, backflushed components are removed from inventory in the warehouse/bin location assigned to the operation work center.

  • MIM controlled items auto-obligate?
    Controls how serial and lot-controlled items are handled. It is used in conjunction with the Method for auto-obligation inventory control system option.

Bill of Material Fields

A number of bill of material component fields also impact the backflush process:

  • Picking warehouse
     The warehouse location from which the component is backflushed.

  • Picking bin location
    The bin location from which the component is backflushed.

  • Pick per receipt?
    This field determines if rounding of fractional component quantities is based on the current receipt or by the total quantity received for the order. For example, if a floor stock item has a quantity per of 0.10000 and you receive 1 parent, 1 unit of the floor stock component is backflushed. Assuming nine receipts of 1 of the parent item follow, additional floor stock would not backflushed since 10 (the total parent items received) times 0.10000 (the floor stock quantity per) is 1.00000 and 1 was picked on the first transaction. Alternative, if you select Pick per receipt? 1 would be picked with each receipt and after 10 receipts of 1 parent, 10 floor stock components would have been backflushed.

If the backflushing process could not be completed, the parent item's planner is sent exception notification.