Abstract

When Continental Automotive Systems, Tianjin, China, beganproducing an electronic component known as the silver box, the return rate was more than 1,200 parts per million (ppm), versus a goal of less than 100 ppm. A Six Sigma improvement team used quality tools including trend charts,Pareto charts, and cause-and-effect diagrams to analyze the failure modes for the reported defects, finding that many were not being covered by product testing processes. A combination of technical innovation tools, includingtest coverage analysis, fault insertion, and a testmethods selection matrix, along with Six Sigmaprocess improvement and statistical tools, ledthe team to the solution of adding new testingitems and a new testing station to the process. Adding the new tests reduced silver box returns to fewer than 50 ppm,producing cost savings of $130,000 per year while also strengthening relations with a major customer.