This is a custom CNC machined aluminum 6061-T6 part, used as a knurled knob, anodized to silver.
The surface of the part is sand-blasted to have a matt appearance. The work is done by CNC turn-mill lathes.
Aluminum is light and very easy to be machined. Yet it is very easy to be oxidized (corrod) and the appearance of the material will be worse. By anodizing, the surface of aluminum can be protected by a deliberately formed layer of oxidizing to stop further corrosion. The appearance of anodizing can be made to many colors depending on the voltage being applied. After anodizing, the surface hardness of aluminum is improved.
Also MAO, microarc oxidation, very similar to anodizing, could form a harder surface similar to ceramic, greatly improves the surface wearproof of the material.
