Production Planning and Detailed Scheduling

What This Article Covers

• A definition of part types.
• How the definition helps one think accurately about the bill of material.

Background

I was recently doing some reading for a book on software approaches to improving BOM management and I came across the book Factory Physics. The book has some excellent and very clear definitions of different part types which I wanted to quote here:

1. Part: A part is a piece of raw material, a component, a subassembly, or an assembly that is worked on at the workstation in a plant.
2. Raw Material: Refers to parts purchased from outside the plant (e.g. bar stock).
3. Components: Are individual pieces that are assembled into more complex products (e.g. gears).
4. Subassemblies: Are assembled units that are further assembled into more complex products (e.g. transmissions).
5. Assemblies – (or final assemblies): Are fully assembed products or end items (e.g. automobiles. Note that one plant’s final assemblies may be another ‘s raw material. For instance transmissions are the final assemblies of a tranmission plant, but are raw materials or purchased components to the automotive assembly plant.

Conclusion

The book’s definitions are interesting, partially because I have tended to think of raw material as very unprocessed material. However the book’s point is that raw material is simply what comes into the factory. Factories are increasingly relying upon sub-contracting, which means that the “raw material” is of very processed. For instance motherboards are a raw material for the finished good or final assembly of a computer server. The term assembly is also interesting because the term finished good seems to be more frequently used.

References

“Factory Physics, Foundations of Manufacturing Management, Second Edition,” Wallace J. Hopper and Mark L. Spearman, Irwin McGraw-Hill

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