Screws are commonly used in machinery, electrical appliances and buildings. They are generally made of metal, cylindrical in shape, with concave and convex grooves carved on the surface, such as an inclined surface surrounding the side of the screw, so that the screw can tightly lock the screw cap or other objects. What is the operation process of screws?

Riveting screw

Operation process

（1） Galvanized (blue white, multicolored, black)

1. Pretreatment: thermal degreasing tank (5 tanks) - electrolytic degreasing tank (3 tanks) - rust removal tank (4 tanks)

2. Electroplating: electroplating tank (20 tanks) (ammonium chloride, zinc oxide, luster agent, softener solution).

3. Post treatment: dissolution tank (1 tank) - green medicine tank (1 tank) - (blue white/multicolored/black)

（2） . Blackening:

1. Pretreatment: hot degreasing tank (4 tanks) - rust removal tank (4 tanks)

2. Blackening: Blackening (5 tanks) (flake alkali, sodium nitrite solution)

3. Post treatment: antirust oil (1 tank)

（3） Phosphating:

1. Pretreatment: thermal degreasing tank (1 tank) - rust removal tank (1 tank) - electrolytic degreasing tank (1 tank)

- Surface treatment (1 groove)

2. Phosphating: phosphating (forming skin film)

3. Post treatment: dipped with antirust oil (2 grooves)

（4） . Hot dip galvanizing:

1. Pretreatment: degreasing tank (1 tank) - rust removal tank (1 tank) - FLUX tank (1 tank) - drying

2. Hot dip galvanizing: hot dip galvanizing tank

3. Post treatment: centrifugal treatment - ammonia chloride cooling - water cooling