Piston pins are primarily made of what material?

Piston pins are primarily made of case-hardened steel due to its exceptional strength and durability. This material allows the pin to withstand the high pressures and temperatures encountered during engine operation. Case-hardening involves treating the surface of the steel to create a hard exterior while maintaining a softer, more ductile interior. This combination provides a balance of toughness and wear resistance, which is crucial for components that endure repetitive stress and friction.

Other materials listed, such as aluminum, plastic composites, and carbon fiber, do not offer the same level of strength and temperature resistance required for piston pins. While aluminum is used in various engine components due to its lightweight properties, it lacks the necessary strength when subjected to the intense conditions within an engine. Plastic composites and carbon fiber, despite their advanced characteristics in certain applications, are not suitable for the demands placed on piston pins in small engines. Thus, case-hardened steel remains the preferred choice for its ability to effectively function under extreme conditions.