In the grinding process, the working surface of bearings is ground by high-speed rotating grinding wheel. Therefore, if the equipment is not operated and adjusted according to the operation instructions during grinding, various roughness defects will appear on the working surface of bearings, which will affect the overall quality of bearings.

In precision grinding of bearings, due to high surface roughness requirements, grinding marks on the working surface can often be observed by the naked eye. There are mainly the following surface grinding marks. (Roughness tester is recommended for roughness detection)

Intersecting spiral marks appear on the surface

The reason for this kind of trace is mainly due to the poor flatness and concave-convex phenomenon of the bus of the grinding wheel. During grinding, the grinding wheel only partially contacts the workpiece. When the workpiece or the grinding wheel moves back and forth several times, the cross helix will be reproduced on the surface of the workpiece and can be observed by naked eyes. The pitch of these helices is related to the speed of the workpiece table and the speed of the workpiece, as well as the non-parallel of the grinding wheel axis line and the guide rail of the table.

►The main cause of helix

1. The grinding wheel is not well dressed, the corners are not chamfered, and coolant is not used for dressing;

2. Too much lubricating oil on the guide rail of the workbench, resulting in floating of the workbench;

3. Machine tool accuracy is not good;

4. Excessive grinding pressure, etc.

► The specific reasons for the formation of helix

1. V-shaped guide rail is not rigid enough. When grinding, the grinding wheel is offset and only the edge of the grinding wheel contacts the working surface;

2. During the dressing of the noisy wheel, the reversing speed of the table is unstable and the accuracy is not high, so that the dressing of a certain edge of the grinding wheel is slightly less;

3. Poor rigidity of the workpiece itself;

4. There are broken and peeling sand particles and iron chips from the grinding of workpiece attached to the grinding wheel surface, so the dressed grinding wheel should be washed or cleaned with cooling water;

5. The grinding wheel is not well dressed, and there are local bumps.

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