posuw

Posuw, in the context of metalworking, refers to the controlled linear motion of the cutting tool relative to the workpiece (or, in some setups, of the workpiece relative to the tool) along the cutting axis. It is a key parameter that, together with cutting speed, determines the material removal rate and influences surface finish, dimensional accuracy, and tool wear.

The posuw is typically expressed in different units depending on the operation. For turning, it is often given as a feed per revolution (mm/rev) and, when multiplied by the spindle speed (rpm), yields the feed rate in millimeters per minute (Vf = f · n). For milling, the common unit is feed per tooth (mm/tooth), and the overall feed rate is Vf = fz · z · n, where fz is the feed per tooth, z is the number of cutter teeth, and n is the spindle speed. In CNC programming, feed rate is usually specified with the F command in mm/min (or inches/min).

Posuw settings depend on factors such as material, tool geometry, depth of cut, and desired surface finish. Higher posuw increases material removal and productivity but also raises cutting forces and tool wear, potentially degrading surface quality. Lower posuw reduces wear and improves finish but lengthens cycle time. Typical ranges vary widely; roughing operations use higher values, finishing operations use lower values, and values depend on material and tooling.

In operation, posuw can be controlled manually via handwheel or automatically via CNC control or feed drives. Related concepts include feed rate, cutting speed, and material removal rate.