OEM BOMs and eight improvement opportunities in contract electronics

By Steve Linahan

contract_electronics_BOMElectronic OEM customer BOMs that supposedly exhibit best-in-class standards for manufacturability, repeatability and material control always fall short. Contract manufacturers (CM) know the OEM’s BOM data management failure does not mean the CM is willing to assume these shortcomings.

CMs frequently take the OEM’s data and create new part numbers in the CM’s product documentation management system, applying the contract manufacturer’s internal data management rules, and in process creating divergent part numbers and data.

Eight common OEM BOM challenges CMs deal with regularly include:

1. OEM BOMs should be provided to the contract manufacturer in electronic formats that can be easily uploaded loadable such as in Excel. Manual entry takes time and is also a source for data entry errors.

2. Customer part numbers that are excessively long can be a headache. Just because you have 28 digits available in your ERP systems item master field doesn’t mean everyone has that amount of space in their system. Always best to limit part number lengths between to 10 to 14 digits.

3. Indented BOMs help everyone from buyers and schedulers to program managers and executives. A BOM should be indented by level, with top-level assembly as the parent, and then explodes, by components, down to the next level called the children. This then repeats again and again until all components are at their base component levels and all higher-level parents/assemblies are defined by their children/components. This is BOM genealogy 101.

4. Smart part numbers and their data input fields are commonly used with predefined prefixes that related a OEM customer or OEM product family, whereas suffixes typically define a product’s iteration, model or revision level and base part number sections (in between the prefix and suffix) describe product characteristics such as resistor value. Smart part numbers are not required but they can make part numbers friendlier for systems and functional group users.

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5. Defining BOM reference items such as component program files, assembly instructions, factory consumable items, tooling and test methods should be included in BOMs.

6. In cases of make vs buy items, even buy items should be detailed down to component levels if you retain design control over the item such as with a custom part, programed parts or a cable assembly.

7. Changing part numbers versus revision level ECN/ECOs (and deviations) are common happenings for components, sub-assemblies and assemblies. These edits describes what is included in a ‘change’ and how the change is to be executed. The CM industry generally conforms to the 3Fs: fit, form or function – meaning, any change to any one of these parameters requires the part number to be changed versus bumping a revision level. Changes on a BOM line item (part) that impacts its fit, form or function is not considered similar enough to its predecessor to be interchangeable.

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8. Product/model numbers are created to separate the part numbering system from OEM product branding. Model names help separate branding needs (for marketing and sales) from manufacturing, engineering and services needs for precise control of product revision levels and part numbers. This allows part numbers to change independently without impacting a product model.

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