Blackening Treatment for Industrial Fasteners

Blackening plus oiling is a popular coating for industrial fasteners(like aluminum rivet nuts,steel rivet nuts), because it is the cheapest and looks good before the oil runs out. Due to the almost no anti-rust ability of blackening, it will quickly rust when there is no oil on surface. Even in the oily state, the neutral salt spray test can only last 3 to 5 hours.

Blackened aluminum rivet nuts are also poor in torque and pre-tightening consistency. If you need to improve its performance, you can apply grease on the inner thread and then screw it in during assembly.