Dirty 30 Process to Prevent Manufacturing Defects

Over the years, I've found that looking at 30 examples of the most frequent or worst kind of defect will usually reveal a Pareto pattern that can be solved easily. I've used it extensively in software, but I recently had an opportunity to use it with a manufacturing client. 

They produce high end parts for the aviation industry. One of the parts suffered from excess metal left after dipping the part in a bath of coating material. Some of the metal could be removed using a small metal pick, but this rework was eating into their productivity and profits. Some of the parts had to be scrapped—an undesirable expense. So I had them bring 30 examples of the part to the two-day, Six Sigma, scrap reduction workshop. 

Step 1: I had them lay the part on a piece of paper and trace the outline:



While this doesn't show all of the part detail, it will serve nicely to show where the excess metal is retained. 

Step 2: Create a Checksheet.

Each defective part had already been marked to show were the excess metal resides, so I simply had them place a mark on the sheet corresponding to the location of the excess metal. It creates a type of checksheet that also serves as a Pareto analysis: 


It didn't take long to discover that the excess metal formed mainly on the right side, the side that exits the coating bath last. With this bit of insight in hand, the team immediately started to do root cause analysis (5 Whys) and hypothesize various countermeasures. Too simple! 

Similarly, I worked with the local toll-road in Denver, E-470. A map of the road marked with push pins showed all of the accidents and fatalities. One tiny section had most of the accidents and all of the fatalities. That got them focused on ways to prevent accidents. 

Hospitals suffer from wrong site and wrong patient surgeries. Could a checksheet of the human body help identify ways to prevent wrong site surgeries? 

Get the Idea? You don't need a lot of fancy tools to do the essential analysis needed for a Six Sigma project. Sometimes a simple, hand-drawn checksheet of errors will solve the problem.

Rights to reprint this article in company periodicals is freely given with the inclusion of the following tag line: "© 2008 Jay Arthur, the KnowWare® Man, (888) 468-1537, support@qimacros.com."

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