I. Inspection of Adhesion Strength of Coating on Fastener Screws
There are various methods to evaluate the adhesion strength between the coating and the base metal, including: 1) Friction polishing test; 2) File test; 3) Scratch test; 4) Bend test; 5) Thermal shock test; 6) Compression test.
II. Inspection of Corrosion Resistance of Coating on Fastener Screws
The inspection methods for corrosion resistance of coatings include: atmospheric exposure test, neutral salt spray test (NSS test), acetic acid salt spray test (ASS test), copper-accelerated acetic acid salt spray test (CASS test), as well as corrosion paste corrosion test (CORR test), solution drop corrosion test, immersion test, intermittent immersion corrosion test, and so on.
III. Surface Inspection Methods for Fastener Screws
Surface inspection of fastener screws is divided into two types: one is the inspection before the screws are produced and electroplated, and the other is the inspection after the screws are electroplated. In other words, it is the inspection after the screws are hardened and their surfaces are finished.
IV. Other Inspections for Fastener Screws
Before the fastener screws are produced and electroplated, we inspect the dimensions, tolerances, and other aspects of the screws to ensure they meet national standards or customer requirements. After the surface treatment of the screws, we inspect the electroplated screws, mainly checking the color of the plating and identifying any defective screws.