Quality inspection of bearings

National standard
1. National standard for vibration acceleration (commonly known as Z standard)

This standard was formulated earlier, to measure the vibration acceleration value when the bearing rotates to determine the quality grade of the bearing, which is divided into three quality grades from low to high: Z1, Z2, and Z3. At present, domestic bearing manufacturers are still using the vibration acceleration value to measure the quality of the bearing, which simply reflects the fatigue life of the bearing.

2. Vibration speed standard (commonly known as V standard)

Since the original vibration acceleration standard has not been abolished, this standard appeared as a standard issued by the Ministry of Machinery Industry. It was formulated with reference to European standards and combined with the actual situation and needs of our country. It is used to detect the vibration speed of the bearing to classify the quality level of the bearing (equivalent to national standard). It is divided into five quality levels: V, V1, V2, V3, V4. The quality grades of various ball bearings from low to high are V, V1, V2, V3, V4; the quality grades of roller bearings (cylindrical, conical) from low to high are V, V1, V2, V3 four quality grades.

It reflects the quality of the bearing by detecting the vibration b speed of the bearing in different frequency bands (low frequency, medium frequency, high frequency). It can generally analyze whether the bearing has geometric size problems (such as steel ring ellipse), the quality of the raceway/rolling body, and the quality of the cage. Compared with the vibration acceleration, the bearing quality has been significantly improved. At present, domestically exported bearings to Europe, my country's military and aerospace industry all carry out bearing quality testing in accordance with this standard. At the same time, testing the quality of European imported bearings and distinguishing counterfeit imported bearings provides a feasible means.

There are two parallel standards in bearing quality inspection, and bearings with a high "Z standard" quality level may not have good quality performance when tested with "V standard", and there is no corresponding relationship between the two. This should be paid special attention to in the quality inspection of bearings.