A manufacturer of components for the automotive, heavy transportation, and machining industries was rejecting parts due to dimensional defects. These large, precision-manufactured bearing assemblies were rejected at the worst possible place… the end of the manufacturing line. This is where all of the cost to manufacture has already been incurred and delays in On-time Delivery (OTD) are harder to overcome. The problem with this particular bearing geometry had plagued their organization for years. They called Advanced Process Optimization.
APO formed a Team of Subject Matter Experts (SME) from their staff to do a week long Kaizen Blitz on this problem. We applied Six Sigma techniques as well as Shainin Red X stratification methodologies.. but with an APO spin! During this Kaizen Blitz we took time to educate the Team on the approach. We like to over deliver! In this case it was knowledge transfer.
Advanced Process Optimization was able to box in the problem to four major sources of variation: The measurement system was not reliable, vendor supplied components were out of tolerance, the residual stress from heat treatment, and the method of manufacture.
APO recommended fixes from our experience in bearing manufacture and heat treat processes, realigned the expectation with the vendors, and recommended a new measurement system with reduced influence. The company is now able to produce parts with a near zero defect rate.