Quality control in the automobile maÖHnufacturing process proceeds in a step-by-step manner. First, inspection occurs at the level of individual parts. Manufacturers must strictly guarantee that parts pass national regulations concerning the basic functions of parts (running, turning, stopping, etc.). Important security parts such as brakes and chassis are subjected to particularly stringent checks.
Finally, when the car is fully assembled and ready to be shipped to market, a final inspection of the vehicle's performance and various other factors is conducted. The list of items tested in this inspection is daunting, yet all items must be identical to the test items used by the Land Transportation Bureau. Once the vehicle is passed on to the inspection line, each inspection item is tested and adjusted in order.
The measurement standards used in production processes such as these are traceable to national standards. A collection of 93 in-house standard devices is used in common by all companies for precision management. At the level of secondary standard devices, about 400 such devices, which are calibrated using the at-house standard devices, are in use at all worksites. Because the items produced at each plant vary from auto bodies to engines and many other components, some 50 - 60 secondary standards are required to manage the instruments used in inspection.