Method of Producing Piston of Internal Combustion Engine

A method of producing a piston of an internal combustion engine, the piston having a double layer solid lubricant film formed on a skirt portion thereof, the method comprising:

• producing a naked piston having the skirt portion;
• applying an outer surface of the skirt portion with a first film forming paint which is provided for producing an inner solid lubricant film;
• heating the first film forming paint at a first temperature to cause the first film forming paint to be damp-dried with some organic solvent left therein;
• applying an outer surface of the damp-dried first film forming paint with a second film forming paint which is provided for producing an outer solid lubricant film;
• and
• firing the first and second film forming paints at a second temperature that is higher than the first temperature.

A piston of an internal combustion engine, comprising:

• a naked piston having a skirt portion;
• streaks formed on an outer surface of the skirt portion;
• an inner solid lubricant film formed on the outer surface of the skirt portion while covering the streaks, the inner solid lubricant film being produced by heating a first film forming paint at a temperature of 60° C. to 160° C. for a time less than 800 seconds to dry the same;
• and
• an outer solid lubricant film formed on an outer surface of the inner solid lubricant film, the inner and outer solid lubricant films being produced by heating both the first film forming paint and a second film forming paint provided for the outer solid lubricant film at a temperature of 160° C. to 240° C. for a time of 15 minutes to 180 minutes.