The Mill Gear is cut from a special gear steel casting and is made split and reversible. The pinion, usually integral with the pinion shaft, is cut from an alloy steel forging and heat treated prior to cutting the teeth. The pinion shaft is double ended so it is also reversible. Gear milling is a common CNC milling operation and gear-cutting process of creating a gear. It can be operated either after or instead of forming processes including casting, forging, and extruding. Mill Gear is very useful.