“Backflushing” enables BOM components to be deducted from stock as finished items are completed, often for an entire product structure. Backflushing is not available in DBA because it is not compatible with an MRP and shop control system and it is the source of many inventory problems.
Light manufacturing systems, which focus solely on BOM components and do not have work centers and routings, often advocate “backflushing” because it reduces inventory updating down to a single step. While this may have superficial appeal, it is an inefficient and problematic process for these reasons.
- Backflushing degrades inventory accuracy because you never really know what is on hand for any given component, which also complicates stock counts.
- Backflushing is not compatible with multi-location environments or for components subject to lot/serial control.
- Backflushing is not compatible with an MRP system that generates jobs for subassemblies against interdependent demand instead of one “job chain” at a time.
- Backflushing is not compatible with a time-phased shop control system that releases jobs in correct multi-level order based on material availability.
The only efficient way to update inventory is to issue material to jobs in real time as needed within work centers. This insures accurate on hand quantities to properly drive MRP, job release, and stock counts.