What factors affect the roughness of the cutting surface in the processing of precision parts?

1. The influence of cutting force and friction. When precision parts are being processed and cut, the fillet of the tool's cutting edge and the squeezing and friction on the side facing the workpiece can cause plastic deformation of the metal material, thereby distorting or deepening the existing residual areas or grooves, increasing the surface roughness and causing the processing of brittle materials. At this time, the cutting chips turn into broken particles, and the processed surface often shows traces of particle collapse It leaves many pits, making the surface rough.

2. The influence of built-up edge. When the cutting tool cuts plastic at a certain speed, some small particles on the chip will adhere to the tip of the rake face, forming a high-hardness accumulated edge, which can replace the rake face and the cutting edge for cutting.
When the frictional force between the chip and the accumulated edge is greater than the cold welding strength between the accumulated edge and the rake face, or when it is subjected to impact or vibration, the accumulated edge will fall off, and thus a new up edge will gradually form later. The formation, growth and shedding of accumulation edges can seriously affect the surface roughness of parts.

3. The influence of scale spines. During the cutting process, due to the friction and cold welding of the chips on the cutting surface during the processing of precision parts, the chips will periodically remain on the rake face, thereby squeezing the newly machined surface. In severe cases, the surface may tear. Scaly spines form on the surface, making it rough and uneven.

Due to the influence of the above-mentioned physical factors on roughness, in order to reduce surface roughness, in addition to reducing plastic deformation caused by cutting force, it is necessary to avoid the formation of accumulated tumors and scales during the processing of precision parts.

The main process measures are: choosing a cutting speed that is less likely to cause edge accumulation and burrs, improving the cutting performance of the material, and correctly selecting cutting fluid, etc.