Introduction Of Common Surface Treatment Process For Fasteners-Zinc Coat

Zinc plating is divided into two categories according to the electrolyte, alkaline and weak acid, alkaline galvanizing without cyanide (zincate) galvanizing and cyanide galvanizing, acid galvanizing with chloride and sulfate galvanizing, cyanide-free (zincate) galvanizing and chloride (potassium chloride) galvanizing is a common electroplating process for fasteners.

1) Galvanizing process: Feeding → chemical degreasing → water washing → pickling → water washing → galvanizing → water washing →light extraction →water washing → passivation → hot water washing → drying → discharge.

2) Process parameters for process control

The purpose of the chemical degreasing process is to remove oil on the surface of the product and prepare it for galvanizing. The main material of tank liquid has a degreasing agent (powder), the main control process parameters are degreasing agent (powder) concentration, tank liquid temperature, degreasing time, and so on.

The purpose of the pickling process is to remove the product surface oxide and rust, to prepare for galvanizing. The main material of bath liquid is hydrochloric acid, and the main control process parameters are hydrochloric acid concentration, pickling time and temperature.

(3) the galvanized

The main materials of tank liquid are potassium chloride, zinc chloride, softener and brightener. The main control process parameters are current density, galvanizing time, potassium chloride content, zinc chloride content, boric acid content, temperature and PH value.

(4) light extraction

The purpose of the process is to make the outer coating bright and beautiful. The main materials of the bath liquid are nitric acid (nitric acid/water 30 ml/L) and hydrochloric acid (hydrochloric acid/water 5ml/L). The main control process parameters are the nitric acid content of the bath liquid and the luminous time.

(5) passivation

The purpose of the process is to produce the desired color of the passivation film. The main materials of baths are nitric acid, chromic anhydride and sulfuric acid. The main control process parameters are bath concentration, passivation time and bath PH value.