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Screw inspection method

Screw surface inspection is divided into two kinds, one is after the screw is not produced before the plating of the test, the other is the screw after the plating of the test, which means that after the screw is hardened, the screw surface after a good deal of inspection. Before the screws were produced and before electroplating, we performed inspections on the dimensions, tolerances and other aspects of the screws. See if it has met the national standards or customer requirements. After the surface treatment of the screws, we have inspected the electroplated screws to check the color of the plating and whether there are any broken screws. In this way, when we send the screw cargo to the customer, the customer can smoothly pass the goods when they receive the goods. After screw processing inspection:
First, appearance quality requirements
The inspection of the appearance of the screw is performed in various aspects such as appearance and plating.
Second, the thickness of the screw plating test
1, measuring method
The use of a micrometer, vernier caliper, plug gauge and so on.
2, magnetic method
The magnetic method for measuring the thickness of the coating is a non-destructive measurement of a non-magnetic coating on a magnetic substrate using a magnetic thickness gauge.
3, microscopy
Microscopy is known as metallographic method, which is to magnify the etched fastener on a metallurgical microscope with a micrometer eyepiece and measure the thickness of the coating on the section.
4, timing fluid method
The chronofluidic flow method uses a solution that causes the dissolved coating solution to flow on the partial surface of the coating, and the thickness of the coating is calculated based on the time required for the partial coating to be dissolved. There are plating drop method, anodizing Coulomb method and so on.
Third, the screw coating adhesion strength test
There are many methods for assessing the adhesion of the plating layer to the base metal, which are usually the following.
1, friction polishing test; 2, boring knife method test; 3, scratch method; 4, bending test; 5, thermal shock test; 6, extrusion method.
Fourth, screw plating corrosion test
Coating corrosion resistance test methods include: atmospheric explosion test; neutral salt spray test (NSS test); acetate spray test (ASS test), copper accelerating acetate spray test (CASS test); and corrosion paste corrosion test (CORR test) and solution spot corrosion test; immersion test, inter-dipping corrosion test, etc.