Six Sigma Case Study
Formed Helical Wires for the Japanese Market

This Six Sigma case study looks at how our client's factory was able to break into the Japanese market. For nine years, minor cosmetic issues prevented their products from being approved by Japanese customers. Multiple shots were taken at solving the problem over the years. Lots of money, time, and effort were spent to no avail. When the DMAIC process was finally brought in to tackle the problem, it was solved in three months.

The Problem

In this six sigma case study, we look at a factory in Southeast Asia manufactured formed helical wires as one of their main products. This product was continually rejected during the approval process for the Japanese market over nine years of trying. There were two main causes for the rejection (and both were cosmetic in nature):

  • The wires had glue lumps on the surface which the Japanese customers found to be ugly. These lumps were left over from a gluing process the product has to go through to ensure the wires stick and stay together under tension or load.

  • The wires had scratch marks on the surface which the Japanese customers also found quite unsightly.

Approximately 50% of products had these cosmetic problems and were deemed unacceptable by the Japanese customers.

The factory sold this product to the rest of the world without any problems. The other customers did not seem to mind as the cosmetic issues did not interfere with the product's application - which was to hold electric wires under high stress and load. However, the Japanese are known for their demand of perfect quality and this was no exception.

The Japanese only bought this product from Japanese suppliers as they were able to provide produce products that met all their standards - whether it be application or cosmetic. This was, of course, quite expensive, but after many attempts the customers were unable to find a cheaper foreign source for this product that met all their quality standards.

The Japanese market was very attractive for the SE Asian factory due to the higher prices and margins that could be achieved. High and consistent volumes were also an attraction. If they could break into the Japanese market, it could mean close to $8 Million in extra revenue for the factory in the first two years alone.

The Method

A core team was formed to execute the project to eliminate the cosmetic issues.

First, the team involved all the process experts and brainstormed all the possible inputs that could affect the two main outputs - glue lumps and scratches. Over 40 possible inputs were identified.

The team knew that their outputs have to be measurable. How do you measure if a product looks good enough? How do you measure glue lumps? How do you measure if minuscule scratches are acceptable? There was currently no way to measure this. So the team created a measurement system for the outputs with the help of the customers to ensure that both the sides had the same system and methods of measurement. The outputs were now completely measurable.

Next, a C&E matrix was used to prioritize the inputs. It was decided that the top 10 inputs in the C&E matrix would be tested first.

Then, during the analyze phase, the team used tools such as ANOVA and Regression to analyze random samples (passive experimentation). This helped us eliminate three more inputs that did not have a statistically significant impact on our outputs.

The team then went on to use low resolution design of experiments (DOE) to narrow it down to to three significant inputs. The epsilon squared of the model with these three inputs was 82%. That means that this model describes 82% of the variation that occurs in this process. In the real world, that is huge!

All the team needed to do now was to optimize the process so that the best settings for the three inputs can be found. These settings should give us the optimal levels for our outputs. A response surface design experiment was done to find the optimal settings.

Finally, controls were put in place to ensure that these inputs remain at their optimal settings.

The Result

The product manufactured under the new process and settings were approved by two major Japanese customers. In just one year, the factory has already sold $3 Million of this product to the Japanese customers - a huge revenue increase for the factory.

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