Four Steps to Improve Bill of Material (BOM) Accuracy

If you read my book the Lean Game Plan, you know I talk about having Lean basics in place- Inventory Accuracy, Bill of Material (BOM) accuracy, and 6S before getting more sophisticated.  Today, I want to talk about four steps you can take to improve your BOM accuracy.

An important Lean saying is- increase stability before increasing capability.  Having your inventory accuracy and Bill of Material (BOM) accuracy at a high-level fall under the category of increasing stability.  I have done a lot of work with Aerospace suppliers that use drawings received from their Prime customers.  Sometimes, they receive a model, sometimes they receive a drawing and then develop an internal BOM by interpreting the drawing.

Regardless, it is imperative that the internal BOM be correct or it will lead to parts not being ordered.  Here are four steps your company can take to improve BOM accuracy.


1.  Use a check, do, check method within your document control group.

Have one employee look at the drawing package and develop the Bill of Material from the package. Before moving the BOM package on, have that employee review the items that are critical to quality. Then have a second resource review the developed BOM.

Humans work at about a 1/100 accuracy level.  If you do something 100 times, you will make about 2-5 errors.  That is the quality level that we can expect from ourselves.  If I do the work at a 1/100 quality level and then I check the work that I completed, now I am operating at 1/100 x 1/100 quality level which is 1/10,000 quality levels.

If someone reviews my work, I am adding another 1/100 level of accuracy which is now 1/100 x 1/100 x 1/100 or 1/1,000,000 which is Six Sigma quality levels.

2.  Use Engineering Change Notices (ECN) or Design Change Notices (DCN) and require a 24-hour turnaround time.

For engineers or designers, it is often more exciting to work on new products or designs instead of correcting incorrect BOM’s. Putting a sense of urgency in place will drive a culture of response and support.

Develop a feedback mechanism so employees know their changes were considered.  I had a client that used “yellow sheets” to capture changes operators wished to see made to the BOM or work instructions.  The engineering group reviewed the yellow sheets and either made the suggested change or didn’t incorporate it.  Either way, they gave feedback to the operator, so they knew the change was reviewed.  This helps support a culture of employee engagement.

3.  For new products, have engineers build pre-production units in a 3P (Production-Preparation-Process) environment.

This is a mock-up of the line or area where the new products will be produced.  The purpose is to work out kinks or errors before releasing the product to full production.

I have seen companies use cardboard boxes to simulate product size so they can develop the space requirements, table layouts, process order, etc. when using a 3P process. This will help you identify missing parts that should be in the BOM.  It also helps you identify the tools required for the build process.

4.  Have engineers and designer’s offices on the floor.

This helps drive urgency.  I know many contract manufacturers of printed circuit boards that station their engineers and support staff on the floor to address BOM or process-related issues.  If BOM issues arise, they take immediate action to keep production moving and follow corrective actions like ECN or DCN activities in a real-time manner.

Having experienced these steps in action, I can assure you that deploying them will help improve your BOM accuracy!

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As always, it is an honor to serve you and I hope that you and your company are getting better every day!

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