The screw surface inspection is divided into two kinds, one is the inspection before the screw is produced, and the other is the inspection after the screw is electroplated, that is, the inspection after the screw is hardened and the screw surface is treated well.
After the production of screws and before electroplating, we will check the dimensions, tolerances and other aspects of screws to see if they meet the requirements.
After the surface treatment of the screws, we will inspect the electroplated screws, mainly to check the color of the electroplating and whether there are bad screws.
Inspection after screw treatment:
1. Appearance quality requirements
The inspection of screw appearance is from the appearance, electroplating and other aspects of inspection.
Second, check the thickness of the screw coating
1. Measuring tool method
The dosage has micrometer, vernier caliper, plug gauge and so on.
2. Magnetic method
The magnetic method for measuring the thickness of the coating layer is a non-destructive measurement of the non-magnetic coating layer on the magnetic substrate by using a magnetic thickness gauge.
3. Microscopy
The microscope method is called the metallographic method, which is to magnify the etched fasteners on the metallographic microscope with micrometer eyepieces to measure the thickness of the coating on the cross section.
4, timing liquid flow method
The timing liquid flow method is to use the solution that can dissolve the coating to flow on the local surface of the coating, according to the time required for the local coating to dissolve, to calculate the thickness of the coating. There are plating spot method, anode dissolution coulomb method and so on.
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