Assemblies and sub-assemblies

A sub-assembly is a made item that becomes a component of a larger product. Producing it turns raw materials into a stocked, ready-to-use part.

When to use a sub-assembly

Use one when an intermediate part is built once and reused across several products, or when a stage of production needs its own components, costing, and stock tracking.

Produce a sub-assembly

1. Give the sub-assembly its own BOM.
2. Raise a work order for it.
3. Issue its components and complete the work order — the sub-assembly is received into stock as a finished, on-hand item.

Consume it in a parent build

Add the sub-assembly as a component line in the parent product’s BOM. When you build the parent, the sub-assembly is consumed from stock like any other component.

Each sub-assembly carries its own cost. That cost rolls up into the parent product’s total cost automatically — see production costs and costing.

If you only ever build the sub-assembly to fulfill a parent order, keep its stock low and produce to demand rather than holding finished sub-assemblies on the shelf.

Next steps

For deeper hierarchies, see multi-level and nested BOMs.