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Surface treatment method of screw fastener


Screw fasteners are the most widely used mechanical basic parts and are in great demand.

Surface treatment is the process of forming a covering layer on the surface of the workpiece through a certain method. Its purpose is to give the product surface a beautiful and anti-corrosion effect. The surface treatment methods carried out are attributed to the following methods:

1. Types of surface treatment:

1. Electroplating:

 Immerse the electroplated parts in an aqueous solution containing the metal compound to be deposited, and pass an electric current through the plating solution to precipitate and deposit the electroplated metal on the parts. General electroplating includes galvanizing, copper, nickel, chromium, copper-nickel alloy, etc. Sometimes boiled black (blue), phosphating, etc. are also included. Our company can now galvanize (blue-white, colorful, black) and boil black , Phosphating (gray phosphorus), nickel plating (black nickel, bronze, bronze), etc.

2. Hot-dip galvanizing: 

The carbon steel parts are immersed in a molten zinc plating tank with a temperature of about 5100C. The result is that the iron-zinc alloy on the surface of the steel gradually becomes passivated zinc on the outer surface of the product. Hot-dip aluminum plating is a similar process.

Surface treatment method of screw fastener

3. Mechanical plating: 

impact the surface of the product through the particles of the coated metal, and cold weld the coating to the surface of the product.

2. Operation process:

(1) Galvanized (blue and white, colorful, black)

1. Pre-treatment: thermal degreasing tank (5 tanks)-electrolytic degreasing tank (3 tanks)-derusting 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 and white / colorful / black).

(2) Boiled black:

1. Pre-treatment: thermal degreasing tank (4 tanks)-rust removal tank (4 tanks);

2. Boiling black: Boiling black (5 tanks) (caustic soda, sodium nitrite solution);

3. Post-processing: anti-rust oil (1 tank).

(3) Phosphating:

1. Pre-treatment: thermal degreasing tank (1 tank)-descaling tank (1 tank)-electrolytic degreasing tank (1 tank),-surface treatment (1 tank);

2. Phosphating: Phosphating (forming a film);

3. Post-treatment: dip anti-rust oil (2 tanks).

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cnc machining shopSheet metal, beryllium, carbon steel, magnesium, 3D printing, precision CNC machining services for heavy equipment, construction, agriculture and hydraulic industries. Suitable for plastics and rare alloys machining. It can turn parts up to 15.7 inches in diameter. Processes include swiss machining,broaching, turning, milling, boring and threading. It also provides metal polishing, painting, surface grinding and shaft straightening services. The production range(include aluminum die casting and zinc die casting) is up to 50,000 pieces. Suitable for screw, coupling, bearing, pump, gearbox housing, drum dryer and rotary feed valve applications.PTJ will strategize with you to provide the most cost-effective services to help you reach your target,Welcome to Contact us ( ) directly for your new project.

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