In order to reduce weight, piston pins are generally made of high-quality alloy steel and made into hollow sections. The piston pin bears significant periodic impact loads under high temperature conditions, and due to the small swing angle of the piston pin in the pin hole, it is difficult to form a lubricating oil film, resulting in poor lubrication conditions. Therefore, the piston pin must have sufficient stiffness, strength, and wear resistance, and the mass should be as small as possible. The pin and pin hole should have appropriate clearance and good surface quality.