Case Study 2: Improving Manufacturing Quality

In this case study we helped a client understand the true nature and causes of defects in their product, after they had been struggling with the defects for over a year.  Prior to this, our client was blaming the raw material supplier.  By providing the materials engineering expertise and perspective we helped frame the problem differently, and did not focus on just the supplier.  Instead we considered all of the materials inputs that had an impact on the final product.

Parts were failing a final inspection test that was performed at the last step of the fabrication process.  The assumption that the steel supplier was at fault led our client to spend a great deal of time and money on trying to get the supplier to improve the steel quality.

We first evaluated the incoming material and product specifications criteria and found that there were conflicting criteria for incoming material quality.  At the same time we provided the background information to help the client understand:

1. The state of the art in steel quality.
2. The effects of the steel quality on the reliability of the final product.
3. The defects identified by the non-destructive test.
4. Possible sources of the defects that would result in failure of the quality criteria.

Our client recognized that focusing on the steel supplier was incorrect and limiting from the standpoint of resolving the yield problems.

The process of fabricating the component included machining and heat treating. It was determined that the defects detected could be a result of improper machining, improper heat treating, or a combination of the two, in addition to the raw material quality. A metallurgical examination of the microstructure of a failed sample revealed that it had been heat treated improperly, and was in a poor condition for subsequent machining and use in the final application. Unfortunately, there was nothing in the heat treating specification that indicated the proper microstructure after heat treatment.

The component specifications were revised to include the microstructure requirements. Also, tests were performed to better understand the defects that could be identified with the final inspection test.