EOL (End-of-Line) testing is quality’s final filter. Its goals are to pass units that can be used in the final assembly of a vehicle and fail the defective ones. Unfortunately, manufacturers still experience costs associated with defective parts, such as claims on components that failed before the end of their warranty period.
Despite rigorous EOL testing, defects still slip by.
A manufacturer could make their end-of-line test more accurate, constraining the upper and lower limits of their tests so that more parts fall outside of spec. But there’s a catch. As limits are tightened, a manufacturer inadvertently increases the number of non-defective parts that are incorrectly classified as defects by EOL testing. These “false positives” decrease FTT, as they are pulled out of production just like any other defect would be. Regardless of whether a unit is a false positive or an actual defect (a true positive), any failed part needs to be reworked or scrapped. This impacts a line’s KPIs and the manufacturer’s bottom-line.
It’s a tradeoff: A manufacturer can catch more defects but mistake good parts for bad, paying more for scrapped parts, or catch fewer defects but pay more in warranty costs, gaining a reputation for producing poor quality components. In the end, manufacturers are stuck between end-of-line testing and a hard place.