INTERNAL COMBUSTION ENGINE PISTON, METHOD FOR MEASURING FILM THICKNESS OF INTERNAL COMBUSTION ENGINE PISTON, AND MANUFACTURING METHOD FOR INTERNAL COMBUSTION ENGINE PISTON

摘要

This piston is provided with a piston body and a film. The film has a film body and a film thickness measurement recess. The film thickness measurement recess is opened toward a combustion chamber, and has a bottom section, an opening edge section, and a peripheral wall section lying between the bottom section and the opening edge section. At least some portions of the opening edge section and of the peripheral wall section are composed of the film body. At least a portion of the bottom section has a film thickness measurement reference surface where the film body is absent.