Managing Multi-level BOM

Managing Multi-level BOM

Imagine your manufacturing process produces sub-assembly components before the finished product. How should you handle the BOM in this situation?

Sub-assembly BOMs must be created first, and these BOMs must be connected to the BOM of the finalized product. The BOM for Brush Bristles (subassembly) is connected to the BOM for the Shaving Brush, as can be seen in the following screenshot (final product). The Bill of Materials master's Materials table shows this.

The "Materials" table simply displays the sub-assemblies, whereas the "Materials Needed (Exploded)" table displays every raw material needed to produce the finished good.

Table of BOM ingredients showing subassembly

The only items visible in the exploded view are the raw materials:

Use the "Use Multi-Level BOM" checkbox to use multi-level BOM in a work order. This is by default turned on. Leave this enabled if you want to plan materials for sub-assemblies of the manufactured item. Disable this checkbox if you plan and produce the sub-assemblies independently.

To better comprehend this, let's look at another scenario in which a computer is being put together. The sub-assemblies, the hard disk and DVD drive, are also produced. Here is how the multi-level or nested BOM will appear:

Personal Computer (FG Item)
Mother Board
SMTP
Accessories and wires
Hard Disk (sub-assembly)
Item A
Item B
Item C
DVD Drive (sub-assembly)
Item X
Item Y
Item Z

Caution

Use caution when changing a sub-BOM. assembly's To reference the revised BOM for that part, the part that contains the sub assembly with the updated BOM will need to be updated. Changing a screw on a low level assembly will, in practice, cause a chain reaction of updated Bills of Material to cascade up through the BOM hierarchy.

Taking the aforementioned personal computer as an example. Hard disk is used by a personal computer (PC-001 with BOM-PC-001) (HDD-001 with BOM-HDD-001). The three products displayed are part of BOM-HDD-001 (Item A, B and C).

The BOM-HDD-002 must be updated if Item C needs to be swapped out for Item D. (with Items A, B and D). After that, the Hard Disk (HDD-001) is revised to make reference to the new BOM-HDD-002. Yet, BOM-PC-001 continues to relate to HDD-001 via BOM-HDD-001. The Exploded BOM for PC-001 will not reflect the change from Item C to Item D.

To make this modification, BOM-PC-002 must be made referencing HDD-001 with BOM-HDD-002.