Bills of materials: defining the recipe and its quantity basis

A bill of materials describes what is needed to make a defined base quantity of a product. Quantities, units, scrap allowances and supply methods determine the component requirement. A BOM is a recipe, not a record that material has already been consumed.

DNA BOMs are versioned and can cover all variants or a specific variant. Components can be manually issued, backflushed or subcontracted. Tree, Explosion and Where-Used views answer different questions: structure, required quantity and which products depend on a component.

Why the base quantity matters

A recipe needs a defined output basis. The same component number can mean very different requirements depending on whether it is stated per one finished unit, ten units, or a batch.

The base quantity allows the requirement to scale. Units also matter: kilograms, litres, pieces, and metres are different measurements. A correct numerical factor with the wrong unit can produce an unusable plan.

A scaling example

A BOM for 10 assemblies requires 20 brackets. A planned run of 50 assemblies needs 100 brackets before any defined scrap allowance. Entering 20 as a per-unit quantity instead of a per-base-quantity requirement would create a tenfold planning error.

The requirement is proportional to the output basis before other defined allowances. Scrap or yield assumptions can add another planning consideration, but they should remain identifiable rather than hidden inside unexplained component quantities.

Variants and versions

DNA BOMs can apply to all variants or a specific variant. This matters when a product family shares a broad design but particular versions require different components. A large assembly may need a different bracket or quantity from a small one.

Versioning preserves the recipe's history and applicability. A new approved recipe should not make it impossible to explain which components an earlier order was intended to use.

Component supply methods

DNA distinguishes manual issue, backflush, and subcontract-related component treatment. The supply method describes how consumption or provision is represented in the process.

Manual issue provides an explicit material movement. Backflush can derive consumption from a production confirmation under the configured relationship. Subcontracting introduces an outside supplier and a need to track components provided. These methods should reflect the actual operation and avoid representing the same consumption twice.

A recipe is not a consumption record

The BOM describes the expected requirement. Actual issues, returns, and supported automatic consumption explain what happened. The difference can reveal scrap, substitutions, inaccurate factors, or incomplete recording.

A useful BOM is clear enough to support purchasing, planning, execution, and cost interpretation. It gives those teams a shared definition of what the product requires while leaving actual consumption to the appropriate execution evidence.