Sheet metal in the processing of all kinds of customized cabinet chassis, air conditioning sheet metal and other sheet metal parts, need to do surface treatment for sheet metal parts, such as spraying, electroplating, anode, electrophoresis, etc. As some sheet metal materials do not have the function of anti rust and anti-corrosion, surface treatment is needed to achieve the effect of anti rust and anti-corrosion; in addition, surface treatment can also achieve the effect of beautifying the appearance of products.
The main purpose of surface treatment is: to improve the service life of automotive sheet metal products in harsh environment (i.e. anti rust and anti-corrosion ability); to obtain the required surface effect or function (i.e. to meet the appearance requirements of sheet metal products).
In order to meet the above requirements, the surface treatment process of sheet metal products mainly includes:
1. Electro galvanizing: the process of forming uniform, dense and well bonded metal or alloy deposition layer on the surface of parts by electrolysis.
2. Chromium plating: the process principle is the same as that of zinc plating. The corrosion resistance of chromium coating is very strong, which is 7-10 times of that of zinc plating, and the surface is beautiful, but the cost is high.
3. Spraying: the powder is polarized, under the action of electric field force, evenly adheres to the product surface with opposite polarity. It's a physical change. It is mainly through the electrode to polarize the coating (powder), and then the object to be sprayed with the opposite charge. Under the action of electric field force, the powder is evenly attached to the surface of the object. Powder electrostatic spraying will not cause air pollution, powder can be recycled, reduce the consumption cost of materials, coating performance is superior, acid, alkali, salt corrosion resistance is good, adhesion is also high.
4. Electrophoresis: under the action of anode and cathode, charged coating ions move to the product surface and deposit to form coating. It's a chemical change. Electrophoretic paint film has the advantages of fullness, uniformity, flatness and smoothness. The hardness, adhesion, corrosion resistance, impact performance and permeability of electrophoretic paint film are obviously superior to other coating processes. The most common electrophoretic color is black, and other colors are also available.
5. Plastic dipping: metal plastic dipping is a new technology for anti-corrosion of metal surface. Plastic dipping is a heating process, including metal preheating, material dipping and solidification. When dipping, the heated metal sticks to the surrounding material. The hotter the metal is, the longer the dipping time is, and the thicker the material is. Dip molding is widely used: it has rich color, good protection, excellent cold resistance, heat preservation and acid and alkali resistance.
Spray is generally paint sandblasting, sandblasting mainly uses compressed gas or high-speed rotating impeller to accelerate the impact of abrasive on the substrate surface, remove oil, rust and residues, make the substrate surface clean and rough, and also make the surface produce internal stress, which is beneficial to improve the fatigue strength.
The process of sand blasting is also particular
1. Before sandblasting, the surface must be clean, free of oil and moisture, so as not to pollute the sand particles;
2. Single side sandblasting is easy to deform and is not recommended;
3. Sand blasting is impacted by high-pressure gas, which makes the workpiece easy to deform. Therefore, a solid fixture should be used as the support body, and the strong air flow should lead to the four shallow sand particles, which has a certain impact on the hardware parts of the contact surface;
4. Under the action of external force (such as bending, die forming, etc.), it is easy to make the sand particles of the sandblasted workpiece fall off or cause obvious indentation;
5. There are many types of sand types and specifications, which should be selected according to the structural requirements and the size, shape and hardness of the parts;