BOM

A BOM expresses the parts and quantities that make up a product, and how those parts are themselves built from lower-level items, as a tree. Purchasing orders against it; production stages material against it.

For execution, the BOM matters because it is the basis for issue verification. Comparing the BOM attached to a work order against what is actually scanned on the floor blocks a wrong part at the moment it happens.

A frequent difficulty is the difference between the engineering BOM and the manufacturing BOM. Engineering structures by function, manufacturing by build sequence, so using one for the other leaves the floor with instructions that do not match reality.

• Attach it to work orders so the floor sees required parts and quantities.
• Verify scanned material against it to block mis-issue.
• Derive material consumption from production results and post it to inventory.

The engineering BOM says what the product is made of; the manufacturing BOM says in what order it is built. The latter carries sub-assemblies and process steps. Conflating them produces work instructions that do not match the actual sequence.