Roughness of turning surface, rough turning and fine turning adapt to different requirements

Surface roughness is the core index to measure the turning quality. It is represented by Ra value (μ m). The smaller the Ra value is, the smoother the surface is, and the higher the fitting accuracy, wear resistance and service life of the parts are. The surface roughness requirements of rough turning and fine turning are significantly different, which shall be reasonably set according to the application of parts.

Roughness of rough turning surface: as the core objective is to remove the allowance, the requirement for surface smoothness is relatively low, and the machined surface will have obvious tool marks. The value range of Ra is generally Ra10 μ m-Ra20 μ m, so it is unnecessary to pursue too high smoothness and avoid increasing the processing cost. The surface roughness after rough turning can meet the requirements of fine turning process to ensure that the tool can smoothly cut during fine turning.

Finish-turning surface roughness: the core objective is to obtain high-quality surface, and the Ra value range can be divided into several grades according to the part accuracy requirements:

Conventional fine turning: Ra1.6 μ m-Ra6.3 μ m, applicable to common mating parts, such as common shaft sleeve and support;

Precision finishing: Ra0.16 μ m-Ra1.6 μ m, applicable to precision fitting parts, such as automobile engine shaft, machine tool spindle, etc;

Mirror finish turning: Ra0.01 μ m-Ra0.04 μ m, applicable to high-end precision parts, such as optical parts, medical implants, etc. Diamond cutters and high-precision machine tools are required.

Practical operation skills of Richeng: the surface roughness is mainly affected by cutting parameters, tool quality and workpiece material. During fine turning, reduce the feed, improve the cutting speed, and match with sharp finishing tools, which can significantly reduce the Ra value; When processing plastic materials (such as aluminum alloy), it is easy to produce chip beading, so it is necessary to improve the cutting speed or use cutting fluid to avoid scratching the surface; When machining brittle materials (such as cast iron), the cutting depth shall be controlled to avoid pockmarks on the surface. By optimizing the tool selection and cutting parameters, we can accurately control the surface roughness according to customer requirements and meet the use requirements of different scenes.