Hardcoating is a variation of the sulfuric acid anodizing process and produces a thicker more durable coating than the conventional anodizing process. The nominal thickness of hardcoating is approximately .0018” to .002” thickness.

Hardcoating being file hard is desirable for its resistance to abrasion and approaches the life of tool steel. Hardcoated aluminum is often used to replace a steel part to reduce weight and still maintain the equivalent wear ability.

It is important to note that when designing close tolerance parts the coating thickness is a serious matter to consider. Surface build-up will be approximately one half of the coating thickness. One half the thickness is penetration and one half is surface build-up. One must also take into consideration that with a ± .0005”.

Before designing or machining a close tolerance part it is important to consult with the company that will be doing the anodizing. It is most important that both parties fully understand the surface build-up and the tolerances.