• tan@nbzyl.com

How to test hex bolts

 

1. We usually look at the appearance of the bolts with our eyes to see whether the electroplated black zinc of the bolts is fine, whether there are spots or not.

2. Tightness test of bolts. Clean the oil layer on the fastener surface with gasoline or cleaning agent, soak it in 3% neutral copper sulfate water for 40-60s, and observe it with naked eyes after there is no trace on the surface.

3. Inspection of corrosion resistance of bolts. Clean the oil layer on the fastener surface with gasoline or cleaning agent, soak it in 0.17% sulfuric acid solution for 20-40s, and observe it with naked eyes after there is no trace on the surface.

4. Wear resistance test of bolts. Clean the oil layer on the fastener surface with gasoline or cleaning agent, hang the glass tube with an inner diameter of 10mm and a length of 500mm vertically above the fastener to be measured, and the inspection surface of the fastener is 45 ° from the glass tube, with a distance of 30mm. Install a funnel above the glass tube, and weigh 100g of quartz sand with a particle size of 0.5-1.0mm and sharp corners. The sand will fall freely and impact the fastener surface. After the sand flows, gently wipe the fastener surface, Immerse in 0.5% neutral copper sulfate solution for 30s, take it out and wash it with flowing water, and observe it with naked eyes.

5. Cleaning quality inspection for blackening film of bolts. After the fastener is blackened and cleaned, and before saponification and oil immersion, drop 1-2 drops of 10% phenolphthalein alcohol solution on its surface. If the solution is pink, it indicates that it is not clean.

6. Geometric dimension inspection. According to the structural shape, drawings and process documents of fasteners, inspect with corresponding tools, cards and measuring tools.

7. Inspection quantity of bolts.

① During mass production, all important appearances shall be inspected; The appearance of general fasteners shall not be less than 10 pieces. The compactness and cleaning quality inspection shall not be less than 1-3 pieces per batch.

② All fasteners produced in the next batch or with special requirements shall be inspected; Or spot check according to process documents.

③ If some items in the sampling inspection are unqualified, the quantity shall be doubled for re inspection. Those still unqualified in the re inspection shall be treated as rework or scrapping.


Post time: Oct-08-2022

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