Self-tapping screws are also called quick-thread screws. They are also commonly used in our lives. They are mostly used to connect thin metal plates (steel plates, saw plates, etc.). So how to detect the surface of self-tapping screws?
1. One is the inspection after the self-tapping screw is produced and before it is electroplated. We inspect the size and tolerance of the self-tapping screw to see if the customer's requirements are met. Mainly a measuring tool method: the amount used has a micrometer, a vernier caliper, a plug gauge, etc.
2. The other is the inspection after the self-tapping screws are electroplated, mainly to inspect the color of the electroplating and whether there are broken screws. In this way, when we deliver to the customer, the customer can be satisfied after receiving the goods. The inspection after the surface treatment of the self-tapping screw includes: the appearance of the self-tapping screw, the plating layer and other aspects are inspected.
The magnetic method measures the thickness of the coating layer, which is a non-destructive measurement of the magnetically basic non-magnetic coating layer with a magnetic thickness gauge.
Microscopy is also called metallographic method. It is to magnify the etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the section.
⑶ Time flow method
The chronograph flow method is to use a solution that can dissolve the coating to flow onto the partial surface of the coating, and calculate the thickness of the coating according to the time required for the partial coating to dissolve, as well as the coating spot method.