Definition of the surface roughness of precision parts processing and its impact on parts

Definition of surface roughness:

    Surface roughness refers to the micro-geometry error composed of small spacing and peaks and valleys on the processed surface of the part. It is generally formed by the precision part processing method used and other factors. On the same surface of the part, except for the micro-geometry In addition to the shape error (surface roughness), there are macro geometric shape error (shape error) and intermediate geometric shape error (surface waviness). Their shape is generally wavy. In the precision parts processing industry, we often use the size of the wave distance To divide these three types of errors:

    (1) Wave distance greater than 10mm belongs to the shape error range

    (2) The wave distance within 1~10mm belongs to the surface waviness range

    (3) Wave distance less than 1mm belongs to the range of surface roughness

Definition of surface roughness

The effect of surface roughness on the performance of parts:

    Even if the surface roughness of the workpiece processed by precision parts is only very small processing traces, it is closely related to the wear resistance, matching properties and corrosion resistance of precision mechanical parts.

1. Effect on friction and wear resistance:

The rougher the actual surface of the part, the greater the friction factor and the faster the wear between the two surfaces.

2. Impact on the nature of coordination:

    For the parts with rougher surface, in the clearance fit, the peak of micro unevenness will accelerate the wear and increase the clearance; for the interference fit, because the peak of the rough surface is squeezed into the valley when pressed into the assembly, resulting in actual The amount of interference is less than the required amount of interference, so that the joint strength is reduced.

3. Effect on corrosion resistance:

The rough surface is easy to cause corrosive substances to adhere to the microscopic valleys on the surface and penetrate into the metal layer, causing rust.

In addition, the surface roughness has a great influence on fatigue strength, contact stiffness, sealing performance of the joint surface, appearance quality and surface coating quality.