Function and treatment of blackening of metal spring
Metal spring in the use of the environment to improve the corrosion resistance or change the appearance of color, will require stamping manufacturers to do some surface treatment. The common surface treatment of spring is blackening.
Blackening is a common means of chemical surface treatment and a method of steel surface treatment. The function is to use chemical reaction method to make metal spring leaf form a layer of tight protective film, to prevent the spring piece from being corroded.
There are two ways of blackening, oxidation treatment and phosphating treatment. These two kinds of blackening treatment have low cost and high production efficiency. Oxidation treatment is commonly used by manufacturers of stamping spring. The oxidation methods include salty oxidation, alkali free oxidation and electrolytic oxidation. Most of them are alkaline oxidation. Phosphating the method of forming a phosphate film insoluble in water on the metal surface by placing the spring in a phosphate solution containing manganese, iron and zinc. The appearance of phosphating film is dark gray, gray or black gray, and has no luster.
Blackening process is widely used in steel spring leaf, clock, pointer, hairspring, screw, instrument shell and some mechanical parts.