Vacuum coating technology is a new material synthesis and processing technology. Vacuum coating equipment is an important part of coating industry. In the words of a vacuum coating entrepreneur, the vacuum coating surface technology is to make “beauty” for customers’ products — more colorful and bright appearance. Vacuum coating technology has been widely used in metal cutting tools, optical instruments, integrated circuit manufacturing, solar energy utilization, flat panel display, building glass and automotive glass, anti-counterfeiting technology, aircraft protective coating, information storage field, sensors, etc.
Which vacuum pumps are suitable for vacuum coating.
The commonly used vacuum pumps for vacuum coating are as follows:
I. rotary vane vacuum pump for vacuum coating
The rotary vane vacuum pump selected in vacuum coating is mainly composed of pump body (stator) and rotor. There are more than two rotors in the rotor slot, and some pumps have springs between them. The rotor is installed eccentrically in the pump cavity, and the gap between its outer edge and the top surface of the pump cavity is 2-3 μ M. When the rotor rotates, under the action of centrifugal force, the rotary vane slides back and forth along the groove and keeps contact with the inner wall of the pump chamber all the time. The pump chamber is divided into two or several variable volume chambers. When the rotor rotates clockwise, the volume of the suction chamber connected with the suction port increases gradually from zero, and the pressure of the gas in the chamber decreases, and the extracted gas is continuously inhaled from the suction port. At the same time, the volume of the exhaust chamber connected with the exhaust port changes from large to small, and the gas in the suction chamber is compressed. When the gas pressure is higher than the atmospheric pressure, open the exhaust valve to exhaust the atmosphere. When the rotor rotates continuously, the pump will pump air continuously.
II. roots vacuum pump for vacuum coating
The limit vacuum of roots pump in vacuum coating depends not only on the structure and manufacturing accuracy of the pump itself, but also on the limit vacuum of the previous pump. In order to improve the limit vacuum of the pump, roots pump can be used in series. The working principle of roots pump is similar to that of Roots blower. Due to the continuous rotation of the rotor, the extracted gas is drawn into the space V0 between the rotor and the pump shell from the air inlet, and then discharged through the exhaust port. As the V0 space is totally closed after suction, the gas in the pump cavity is not compressed and expanded. However, when the top of the rotor turns the edge of the exhaust port and the space V0 is connected with the exhaust side, because of the high gas pressure at the exhaust side, a part of the gas flows back into the space V0, which makes the gas pressure suddenly increase. As the rotor continues to rotate, the gas exits the pump. In the cavity of roots pump, two ‘8’ shaped rotors are vertically installed on a pair of parallel shafts, and a pair of gear belts with a transmission ratio of 1 move in reverse synchronous rotation with each other. There is a certain gap between the rotors, between the rotors and the inner wall of the pump casing, which can realize high-speed operation.
III. water ring vacuum pump for vacuum coating
The pump body of water ring vacuum pump with vacuum coating is filled with appropriate amount of water as working fluid. When the impeller rotates clockwise in the direction indicated, the water is thrown around by the impeller. Due to the centrifugal force, the water forms a closed ring of approximately equal thickness, which is determined by the shape of the pump cavity. The inner surface of the upper part of the water ring is just tangent to the impeller hub, and the inner surface of the lower part of the water ring is just in contact with the top of the blade (in fact, the blade has a certain insertion depth in the water ring). At this time, a crescent space is formed between the impeller hub and the water ring, and this space is divided into several small cavities with equal number of blades by the impeller. If the upper 0 ° of the impeller is taken as the starting point, the volume of the small cavity will increase from small to large when the impeller is 180 ° before rotation, and it is connected with the suction port on the end face. At this time, the gas will be inhaled, and when the suction is finished, the small cavity will be isolated from the suction port; when the impeller continues to rotate, the small cavity will change from large to small, so that the gas will be compressed; when the small cavity is connected with the exhaust port, the gas will be discharged out of the pump.
Where can vacuum be used in coating processes?
Vacuum plays a decisive part in many coating operations in which metals, plastics or glass are deposited in vapour form. In many cases these processes would not be possible without vacuum. A medium or high vacuum is applied to the chamber for its evacuation at the start of the process, after which reaction gases are extracted or solid raw materials vapourized.
All these processes have a common requirement: a completely reliable medium or high vacuum in the chamber that precisely matches the coating process. Such coating operations are carried out to alter the surface characteristics of the material, such as hardness or resistance to corrosion. Vacuum coating may also be used to improve the adhesive or wetting qualities of the material, or to make surfaces permanently hydrophobic or hydrophilic.
The high cost performance of vacuum coating and the pollution of traditional electroplating to the environment have forced vacuum coating to become the mainstream. For customers, what they need is not the lowest price, but a trade-off between the brand and the price. The most suitable choice is to choose a brand of vacuum pump that can meet the demand and the budget. The above is the choice of vacuum pump for vacuum coating!