Strict backflush
Backflush each material only from the storage unit on its material line, and stop the work when that storage unit is short.
By default, a that finds its material's storage unit short takes the rest from another storage unit with stock. Strict backflush turns that off: each material is drawn only from the Pull From storage unit on its material line, so on-hand stays correct per storage unit.
Turn it on
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Open Settings → Items and find the Strict Backflush card under Bill of Materials.
Turn on the first switch. It reads "Strict backflush is on". Nothing asks for confirmation, and no existing method or job changes.
Choose Prevent negative stock (on by default). On, an operation or job that would take its storage unit below zero is stopped until the stock is there. Off, the storage unit goes below zero and the work still completes.
Press Review on each gap row the card shows: active methods with materials that have no Pull From, and open jobs with materials that have no storage unit. Each opens a searchable list. Fix a method through a new version, since an Active method cannot be edited.
Which lines need a Pull From
A material line needs a Pull From when it is pulled from stock: its method type is not Make to Order, the item is a Part, Material or Consumable, and the item is not Non-Inventory. Purchase to Order, batch and serial lines count.
The rule applies only at a location that has an active work center and an active storage unit. At any other location, backflush works as if the setting were off. Set the Pull From in the bill of materials: expand the line, then under Pull From pick the location and its storage unit. A line that is missing one shows a red "No storage unit" badge.
What it stops
- Activating a method version with a line that has no Pull From.
- Releasing a job with a line that has no storage unit, from the job's Release dialog, bulk release, batch release, or a kanban scan with Auto Release. A new job's line takes the BoM's Pull From, else the item's default storage unit for the location. It never takes the storage unit with the most stock.
- Completing an operation or a job, and issuing a planned material, when its storage unit is missing or short. The check runs before the quantity is recorded, so a refused completion records nothing.
Picked material is used first
Material already picked to the operation's lineside storage unit is consumed before the Pull From is checked. Only the rest must be in the Pull From storage unit. After a pick, the Pull From is the storage unit the oldest pick took the material from.
Batch- and serial-tracked materials still need a Pull From to activate and release, but the operator scans the unit to issue it, as before.