Piston pins are important part of the engine. It plays pivotal role in the reciprocating internal combustion engine. Mechanically, they are extremely simple part and most of the time piston pin manufacturers design it simply as short length of solid bar. Many production piston pins are not removed from this easiest interpretation, being a simple steel thick-walled cylinder. Piston pins designed for race engines are complex than general car engine pins, as manufacturers need to reduce mass to an absolute minimum and the cost concern is also less.
Engineers need to decrease the diameter and length to chasing the minimum mass, within the critical constraint of having to maintain adequate stiffness. There are other things to look after, the most critical one is to ensure sufficient life in the component by keeping stresses inside acceptable bounds for the material.
The most common material used by manufacturers for piston pins is the steel. The surface of the steel is often hardened to enhance wear resistance. The hardening method selected by them will determine the material choice. There are two main choices for hardening-carburising and nitride hardening. These both have beneficial side-effect of imparting critical compressive residual stresses to the surfaces of the part. This improves fatigue resistance as compared to the part without these stresses.
Carburising steels are graded with low carbon content and additions of nickel, manganese, and chromium. It is the low content of carbon that lets diffusion of carbon into the surface. Nitriding steels have extra elements like aluminium, chromium, and titanium that form nitride. These steels are similar to steels that manufacturers usually use to craft racing crankshafts.
The wear resistance of the steel pins has been enhanced by manufacturers with the help of hard, thin coating applications.
Steel is not the only metal of choice for piston pins. Many manufacturing stores also provide titanium pins. Titanium has much lower density than that of steel and its elastic modulus is low as compared to steel.
Manufacturers of piston pins never suggest their customers to replace their steel pins with titanium pins. Titanium metal has poor wear behavior in sliding contacts and this is why piston pin manufacturers coat them to achieve an acceptable level of durability. For more details on titanium vs steel piston pins, you can contact manufacturers and exporters who are already dealing in these types of piston pins.