Today it is a vacant plot. Back in the early 1990s, a stamping plant was there, with three main buildings supplying North American automotive final assembly operations. I was an inspector working the second shift, assigned to a stamping line producing outer panels for an automotive door.
While inspecting panel surfaces one hot summer day, I noticed an odd pattern. When a defect occurred in the outer panel surface on one panel, it was followed by a defect at a lesser degree at the same location on the next three panels. A total of four panels were scrapped at a cost of $50 each. This pattern repeated throughout the night, which meant that each event cost the company $200. Because this was long before I knew about Six Sigma, I planned to just use root cause analysis. I had already determined the four rejected panels were not random. But what was the common cause?