Surface finish on A36 steel

A 36 steel is not a particularly difficult material to machine. However, it can be challenging to achieve an exceptional surface finish, especially when a part calls for a 63.5 mm (2.5″) axial depth of cut. The challenge for this ProvenCut recipe was to achieve an acceptable — or even excellent — finish with a tool length-to-diameter ratio of 5-1.

The larger a tool is, the stiffer it is. But large-diameter carbide cutting tools present problems. The cost goes up drastically. A 19.05 mm (0.75″) tool may cost over twice the price of a 12.7 mm (0.5″) tool — and rightfully so, as the former has 2.3 times the amount of carbide. For that reason, large-diameter endmills rarely are purchased or kept in inventory as frequently as smaller-diameter ones. Setting aside tool price, larger-diameter endmills also create more tool pressure, making them difficult to run on many common 40-taper machining centers.