To provide a plating method for efficiently forming a plated film on an inner peripheral wall surface of a bore of a cylinder block.
This plating method includes honing the inner peripheral wall surface of the bore of the cylinder block to remove the oxide film and the like thereon, simultaneously adjust the maximum height of irregularities on the inner peripheral wall surface to 20 μm or less, and control the real surface area/apparent surface area to 1.2 m2/m2 or larger, and preferably to 1.4 m2/m2 or larger. A salient 22 is formed on cross hatching by moving a honing head back and forth in a depth direction of a bore while rotating the honing head. The honing-head preferably has grind stones with grain sizes of #80 to #1000 thereon. Subsequently, thus roughened inner peripheral wall surface is plated with zinc to have the plated film formed thereon. When the inner surface has a ratio of real surface area/apparent surface area of 1.2 m2/m2 or more but less than 1.4 m2/m2, it is preferable to heat-treat the cylinder block after the plated film has been formed on the inner surface. Even when the inner surface has a ratio of real surface area/apparent surface area of more than 1.4 m2/m2, it is recommended to heat-treat the cylinder block.
YOSHIMOTO NOBUHIKO
NAGATA MAKOTO
Toshiyuki Miyadera
Tatsuhiko Sato