You walk to the brake department, where you see piles of work-in-process. Stacks of panels of multiple thicknesses sit with an acute bend near one edge—a hem, half formed. At the brakes, you see ...

But a closer look reveals that he is banging sheet metal with a well-used hammer. His speed and accuracy would impress any percussionist. Yamazaki, a 56-year-old auto parts maker at leading ...