DESIGN & FINISHING GUIDE

A Guide to Wear-Resistant Finishes

For parts that slide, rotate, or endure abrasive contact, a wear-resistant surface is essential for a long service life. This guide covers the key finishing processes used to harden part surfaces.

What is Wear Resistance?

Wear resistance is a material's ability to resist material loss from mechanical actions like friction, abrasion, and erosion. While choosing an inherently hard material is one strategy, it is often more cost-effective to machine a part from a standard, easy-to-machine metal and then apply a very hard surface finish.

This approach creates a part with a tough, ductile core and an extremely hard, wear-resistant outer "case," providing the best of both worlds.

A set of gears, a classic application where wear resistance is critical

Finishes for Maximum Durability

Hardcoat Anodizing (Type III)

This process creates a thick, dense layer of aluminum oxide on the surface of aluminum parts. This ceramic layer is extremely hard (typically 60-70 Rockwell C), providing excellent scratch and wear resistance. It is the go-to choice for durable aluminum mechanical components.

Case Hardening (Steel)

This is a heat treatment process for low-carbon steel parts. The part is heated in a carbon-rich atmosphere, causing carbon to diffuse into the surface. The part is then quenched and tempered. This creates a very hard, wear-resistant outer skin (the "case") while leaving the core of the part tough and ductile.

Hard Plating (Chrome/Nickel)

Electroless nickel plating and hard chrome plating are processes that deposit a hard, low-friction metallic coating onto a part. They provide excellent wear resistance and corrosion protection, and are often used to build up worn surfaces on industrial shafts and hydraulic components.

Wear Resistance FAQ

Does Hardcoat Anodizing change the part's dimensions?

Yes, significantly. A standard Type III hardcoat builds up thickness on the surface, typically about 0.025mm (0.001") per side. This must be accounted for in the design for any features with tight tolerances. For example, a hole will get smaller by 0.05mm in diameter.

What is the difference between hardness and toughness?

Hardness is the resistance to scratching and indentation. Toughness is the resistance to fracture or chipping from an impact. A very hard material (like ceramic) is often not very tough (it is brittle). Case hardening is a popular process because it creates a part that is both hard on the surface and tough in the core.