Briefly describe the difference between turning, drilling, boring and grinding the inner circle (hole).

1. turning: it is mainly used for machining various internal and external revolving surfaces, such as cylindrical surfaces and conical surfaces. In the process of turning, the workpiece is installed on the lathe spindle through the fixture and rotates with the spindle. The cutter moves along the axial direction of the workpiece to cut out the required shape and size. Turning is suitable for workpieces with high machining accuracy and small surface roughness.

2. Drilling: it is mainly used to drill holes in workpieces, and the depth and diameter of drilling holes depend on the type of drill bit and processing requirements. When drilling, the drill bit rotates at high speed and moves along the axial direction at the same time to drill holes. Drilling is suitable for machining holes with smaller diameters, such as threaded bottom holes and oil holes.

3. Boring: mainly used for machining existing holes, such as cylinder barrel and valve hole. In the process of boring, the boring tool rotates in the workpiece hole and moves along the axial direction at the same time to cut out the required shape and size. Boring is suitable for machining large diameter holes, such as engine cylinders and hydraulic valve holes.

4. Grinding: mainly used for machining hardened or non-hardened surfaces, such as gears and shafts. In the grinding process, the grinding wheel rotates at high speed, while the workpiece rotates or reciprocates to cut out the required shape and size. Grinding is suitable for machining workpieces with high precision and high surface roughness, such as precision bearings and high precision gears.