What inspection should fastener screws go through?

Fastener screws need to be inspected before or after production before they can be formally put into use. Therefore, in order to get better use effect of fastener screws, we must be careful and careful when carrying out these inspections. According to the summary experience, China Standard Parts Network tells you that some fastener screws are inspected and we list the following points.

First, fastener screw coating adhesion strength inspection

There are many ways to evaluate the adhesion between coating and substrate metal, usually the following :1, friction polishing test; 2, file method test; 3, scratch method; 4. Bending test; 5, thermal shock test; 6. Extrusion method.

Two, fastener screw coating corrosion resistance test

The test methods of coating corrosion resistance include: atmospheric exposure test; Neutral salt spray test (NSS test); Acetate spray test (ASS test), copper accelerated acetate spray test (CASS test); And paste corrosion test (CORR test) and solution spot corrosion test; Dip test, dip corrosion test and so on.

Three, fastener screw surface inspection method

Fastener screw surface inspection can be divided into two kinds, one is the inspection of the screw after production before electroplating, the other is the inspection of the screw after electroplating, that is to say, the screw after hardening, screw surface treatment.

Four, fastener screws other inspection

After the fastener screws are manufactured and before electroplating, we check the dimensions, tolerances and other aspects of the screws. See if it meets national standards or customer requirements. After the surface of the screws is treated, we will inspect the electroplated screws, mainly to check the color of the electroplating and whether there are bad screws.