The international standard stipulates that it is divided into 20 classes, from IT01, IT0, IT1, IT2 to IT18.

This grade identifies what tolerances a given process can produce for a given dimension.

This article introduces the processing accuracy that can be achieved by several common processing forms such as turning, milling, planing, grinding, drilling, and boring.

Turning is generally carried out on a lathe to process the inner and outer cylindrical surfaces, end surfaces, conical surfaces, forming surfaces and threads of the workpiece.

The machining accuracy can reach IT10IT7, and the surface roughness is R 100.16 m.

It is suitable for processing flat surfaces, grooves, various forming surfaces (such as splines, gears and threads) and special shapes of molds.

According to the same or opposite direction of the main movement speed and the workpiece feed direction during milling, it is divided into down milling and reverse milling.

It is a finishing process that is widely used in the machinery manufacturing industry.

Drilling is often carried out on drilling machines and lathes, and can also be carried out on boring or milling machines.

Its application range is generally from semi-roughing to finishing.

Iso 2768 Hole Tolerance It6