Several main methods for inspecting finished screws

There are two main methods for inspecting the surface of finished screws: one is the inspection before electroplating after the screw is produced, and the other is the inspection after electroplating, that is, after the screw is hardened and the surface of the screw is treated. Before electroplating, screws should be inspected for dimensions, tolerances, and other aspects after production. See if it meets national standards or customer requirements. After the surface treatment of the screws, the electroplated screws are inspected, mainly to check the color of the electroplating and whether there are any damaged screws. This way, when delivering goods to customers, they can pass customs smoothly. Let's learn about the inspection after screw processing together:

1. Appearance Quality Requirements

The inspection of screw appearance is carried out from various aspects such as appearance, plating layer, etc.

2. Inspection of screw coating thickness

1. Measuring method

The amount used includes micrometers, vernier calipers, plug gauges, etc.

2、 Magnetic method

Magnetic method is a non-destructive measurement of non-magnetic coating layers on magnetic substrates using a magnetic thickness gauge

3、 Microscope method

The microscope method, also known as metallographic method, involves magnifying etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the cross-section

4、 Timing flow method

Timing flow method is to pour a solution that can dissolve the coating onto the local surface of the coating, and calculate the thickness of the coating based on the time required for the local coating to dissolve completely. There are also plating drop method, anodic dissolution Coulomb method, etc

III. Inspection of Adhesion Strength of Screw Coating

There are many methods to evaluate the adhesion between the coating and the base metal, usually including the following.

1、 Friction polishing test; 2. Filing method test; 3. Scratch method; 4. Bending test; 5. Thermal shock test; 6. Squeezing method

4. Inspection of corrosion resistance of screw coatings (based on actual reports)

The inspection methods for corrosion resistance of coatings (based on actual reports) (based on actual reports) include: atmospheric exposure test;