1. We usually look at the appearance of Precision screw with the naked eye to see whether the electroplated black zinc of the screws is beautiful or not, whether there are mottled or not

2. Fineness detection of sports equipment screws. Use a cleaning agent to remove the oil layer on the surface of the fastener, soak it in 3% neutral acid copper water for 4o-6os, and inspect it with the naked eye after there is no water on the surface.

3. Corrosion resistance inspection of sports equipment screws. Use a cleaning agent to remove the oil layer on the surface of the fastener, put it into the aqueous acid solution with a ratio of 0.17 and soak it for 2o-4os, and inspect it with the naked eye after there is no water mark on the surface.

4. Inspection of cleaning quality of blackened film on sports equipment screws. After the fastener is blackened and cleaned, before saponification and oil immersion, drop 1-2 drops of 10% fenphthalein alcohol solution on the surface. If the solution is pink, it means that the cleaning is not clean.

5. Geometric scale inspection. According to the structure shape and pattern of fasteners and the rules of process documents, check with corresponding tools, cards and measuring tools.

6. Inspection quantity of sports equipment screws.

① When producing in batches, the important appearance should be inspected step by step; the appearance of general fasteners should not be less than 1o pieces. The fineness and cleaning quality inspection shall not be less than 1-3 pieces per batch.

②Fasteners produced in batches by a single piece or with other requirements should be inspected step by step; or according to the sampling inspection of the process documents.

③ If some items are unqualified in the sampling inspection, a large number of re-inspection should be carried out. If the re-inspection is still unqualified, it will be repaired or scrapped.