Accuracy requirements for each process of CNC machining center

Accuracy is used to indicate the fineness of the workpiece product. It is a special term for evaluating the geometric parameters of the machined surface and an important indicator for measuring the performance of the CNC machining center. In general, the machining accuracy is measured by the tolerance level, and the lower the level, the higher the accuracy. Car, milling, planing, grinding, drilling, and boring are common processing forms of CNC machining centers. How much processing precision should these machining processes achieve?

1. Turning accuracy
Turning refers to the rotation of the workpiece, and the turning of the turning tool in a plane for linear or curved movement is used to machine the inner and outer cylindrical faces, end faces, conical faces, forming faces and threads of the workpiece.

The surface roughness of the turning process is 1.6-0.8 μm.

Rough turning requires high cutting depth and large feed rate to improve turning efficiency without reducing the cutting speed. The surface roughness requirement is 20-10um.

Semi-finished and refined cars use high speed and small feed and cutting depth as much as possible, and the surface roughness is 10-0.16um.

The high-precision lathe is equipped with a finely ground diamond turning tool for high-speed finishing of non-ferrous metal workpieces with a surface roughness of 0.04-0.01um. This turning is also called “mirror turning”.

2. Milling accuracy

Milling refers to the use of a rotating multi-blade tool to cut a workpiece, which is a highly efficient machining method. Suitable for processing planes, grooves and special shapes such as splines, gears and thread dies.

The machining accuracy of milling is generally 6.3-1.6 μm.

The surface roughness during rough milling is 5-20 μm.

The surface roughness during semi-finishing is 2.5-10 μm.

The surface roughness during finish milling is 0.63-5 μm.

3. Planing accuracy

Planing is a cutting method that uses a planer to horizontally reciprocate the workpiece horizontally. It is mainly used for the shape processing of parts.

The surface roughness of the planing process is Ra6.3-1.6 μm.

The surface roughness of the rough planing is 25-12.5 μm.

The semi-finished surface has a surface roughness of 6.2-3.2 μm.

The surface roughness of the fine planing is 3.2-1.6 μm.

4. Grinding accuracy

Grinding refers to the processing method of using abrasives and abrasive tools to remove excess materials on the workpiece. It belongs to the finishing industry and is widely used in the machinery manufacturing industry.

Grinding is usually used for semi-finishing and finishing, and the surface roughness is generally 1.25-0.16 μm. The precision grinding surface roughness is 0.16-0.04μm.

Ultra-precision grinding surface roughness is 0.04-0.01μm.

The surface roughness of mirror grinding can be less than 0.01μm.

5. Boring

Boring is an internal diameter cutting process that uses tools to enlarge holes or other circular contours. Applications range from semi-roughing to finishing. The tools used are usually single-edged boring tools (called masts).
It is an inner diameter cutting process that uses tools to enlarge holes or other circular contours. Its application range is from semi-roughing to finishing. The tools used are usually single-edged boring tools (called masts).

The precision of the boring of steel materials is generally 2.5-0.16 μm.

The precision of precision boring can reach 0.63-0.08μm.