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Types of screw surface treatment


Surface treatment is the process of forming a covering layer on the surface of the workpiece by a certain method, and its purpose is to endow the surface of the product with beautiful and anti-corrosion effects. The surface treatment methods are attributed to the following methods:


1. Electroplating: Immerse the part to be electroplated in an aqueous solution containing the deposited metal compound, and pass an electric current through the plating solution to precipitate and deposit the electroplated metal on the part. General electroplating includes galvanized, copper, nickel, chromium, copper-nickel alloy, etc., and sometimes blackening (blue), phosphating, etc. are also included.


2. Hot-dip galvanizing: It is done by immersing the carbon steel parts in a zinc-melting bath with a temperature of about 510°C. The result is that the iron-zinc alloy on the surface of the steel gradually becomes passive zinc on the outer surface of the product. Hot dip aluminizing is a similar process.


3. Mechanical plating: impact the surface of the product through the particles of the plated metal, and cold-weld the coating to the surface of the product.





Operation process
(1), galvanized (blue and white, colorful, black)
1. Pre-treatment: 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, gloss agent, softener solution).
3. Post-processing: Melting tank (1 tank) - green medicine tank (1 tank) - (blue-white/multicolored/black).


(2) Blackening:
1. Pre-treatment: thermal degreasing tank (4 tanks) - rust removal tank (4 tanks).
2. Blackening: Blackening (5 slots) (flake alkali, sodium nitrite solution).

3. Post-treatment: anti-rust oil (1 slot).

(3) Phosphating:
1. Pre-treatment: thermal degreasing tank (1 tank) - rust removal tank (1 tank) - electrolytic degreasing tank (1 tank), - surface treatment (1 tank).
2. Phosphating: Phosphating (forming a film).
3. Post-treatment: dip in anti-rust oil (2 tanks).


(4) Hot dip galvanizing:
1. Pre-treatment: 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: Centrifugation - ammonia chloride cooling - water cooling.