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Non-involute gears have reduced specific sliding. Reduced gear sliding has an affect on low speed meshes, where sliding losses predominate. The efficiency of these gears is also increased by the use of less viscous oil. The tooth profile geometry is uniquely defined by the arc shaped path of contact. The gears manufactured by the same rack cutter have the concave convex mesh. The result of enlarged reduced radius of curvature has as a consequence reduced pressure and better lubrication conditions. The geometry of non-involute gear tooth provides substantially higher capacity than any other gearing. The disadvantages of the non-involute gearing are lower transverse contact ratio and great sensitivity to the center distance accuracy.

For cutting tools, geometry depends mainly on the properties of the tool material and the work material. The standard terminology is shown in the following figure. For single point tools, the most important angles are the rake angles and the end and side relief angles. The back rake angle affects the ability of the tool to shear the work material and form the chip. It can be positive or negative. Positive rake angles reduce the cutting forces resulting in smaller deflections of the workpiece, tool holder, and machine. If the back rake angle is too large, the strength of the tool is reduced as well as its capacity to conduct heat. In machining hard work materials, the back rake angle must be small, even negative for carbide and diamond tools. The higher the hardness, the smaller the back rake angle. For high-speed steels, back rake angle is normally chosen in the positive range. There are two basic requirements for thread cutting. An accurately shaped and properly mounted tool is needed because thread cutting is a form-cutting operation. The resulting thread profile is determined by the shape of the tool and its position relative to the workpiece.