Common types of knurling on the surface of copper nuts: herringbone knurled nuts, net knurled nuts, diamond knurled nuts, straight knurled nuts, diagonal knurled nuts, etc. We can distinguish high-quality copper by three points Nut.

　　One point to distinguish the quality of copper nuts can be distinguished from the knurling on the surface of the nut. The outer surface is smooth and free of bumps, embossing, peeling, pinholes, cracks and corrosion.

　　Two points to distinguish the quality of copper nuts, from the quality of the inner surface of the nut, the inner surface is clean, free of oil, impurities and moisture. The internal thread has no burrs, cracks, or breakage. The inner surface, especially the mating cone, must not have dents, scratches, dirt and other defects and corrosion that affect the sealing performance.

　　The three points are the structure size. The structure size should be measured with vernier calipers, ring gauges, through gauges, tooth gauges and other measuring tools, and should meet the drawing requirements. Thread size (pitch diameter, minor diameter, major diameter, pitch) must conform to KB0612-02.050 "Inch Thread Size Specification and Tolerance".

　　Regarding the copper nut series products, after inspecting the above three points, we can basically see the quality of the products!