Each Bill of Materials line item record stores the component or sub-item number and the component quantity required to build 1 of the top level item in the BOM.
A BOM line item can have a positive quantity – indicating it is consumed by the assembly process, or a negative quantity, indicating that the item is produced by or is a “by-product” of the assembly process.
The BOM line item quantity is moved into the shop order lines when a shop order is created from the BOM.
Positive Quantity Component Line
During Shop Order processing, component lines with a positive quantity are deducted from inventory and are added to work in process or WIP when the shop order components are pulled.
The component quantities are removed from work in process and converted to the top level item when the shop order is completed.
Negative Quantity Component Line
Component line items with a negative quantity are added to inventory by the system when a shop order for the top level item is completed.
No adjustment takes place for BOM lines with a negative quantity when a shop order line is pulled or cancelled after being pulled.