How well the vacuum coating machine cleans the workpiece before coating the workpiece is directly related to the yield of the coated workpiece in the later stage. If the cleaning process is done well, the rate of defective products will be greatly reduced, that is, the work efficiency will be improved, and the cost will be saved, because the purchase of vacuum Before the coating machine, everyone pays great attention to the cleaning process. What is the cleaning process like before plating the workpiece? The following is a brief introduction to the vacuum editor, I hope it can help you:

       Cleaning is to remove oil, rust, dust, etc. on the workpiece by chemical or (and) physical methods to ensure that the workpiece obtains better coating adhesion and the smooth progress of production. Cleaning is an indispensable process before PVD coating, and it is also the most important process in PVD coating production. If there is a problem with cleaning, the coating production has to be delayed, the coating process may be interrupted, or there is a problem with the coating adhesion. Lead to customer complaints and compensation, especially in the case of low technical capabilities of coating equipment, cleaning problems, more prone to the above risks.
         There are four factors that affect the quality of cleaning, namely: cleaning time, chemical agents, mechanical action and cleaning fluid temperature. These four factors also affect each other. The weakening of one factor can enhance the effect of the other three factors. to make up for it, and vice versa. Among these four factors, minimizing the cleaning time is also the goal, which can improve the cleaning efficiency. Shorten production time and lead time.
The main cleaning methods and steps should include: chemical spraying, chemical immersion and ultrasonic cleaning, rinsing and drying.
1) Chemical spray
      Spray is very effective for cleaning, it can remove most of the oil and contaminants from the workpiece. Especially for workpieces with holes, it is more effective. The chemical agent sprayed on the workpiece will flow into the hole or the chemical agent will be directly sprayed into the hole to flush the inner wall of the hole. Therefore, when cleaning and loading the card, be sure to allow the workpiece to be sprayed. In addition, if the chemicals sprayed on the workpiece cannot flow away immediately, it will prevent fresh chemicals from continuing to clean the workpiece, and it will not be easy to dry in the subsequent drying steps. Therefore, when installing the card, ensure that it flows to the workpiece. The medicine on it can flow away naturally.
2) Chemical immersion and ultrasonic cleaning
       Ultrasound is a sound wave with frequencies above 20 kHz beyond the range of human hearing. The propagation of ultrasonic waves depends on the elastic medium. When it propagates, the particles in the elastic medium oscillate, and energy is transmitted through the medium in the direction of propagation of the ultrasonic waves. This kind of wave can be divided into longitudinal waves and transverse waves. In solids, both can be transmitted, while in gases and liquids, only longitudinal waves can be transmitted. Ultrasound can cause particle vibration, and the acceleration of particle vibration is proportional to the square of the ultrasonic frequency. Therefore, the ultrasonic wave of several tens of kilohertz will generate a great force, and when the strong ultrasonic wave propagates in the liquid, due to the nonlinear effect, acoustic cavitation will be generated. When the cavitation bubble is suddenly closed, the shock wave can generate thousands of atmospheric pressure around it, and the direct and repeated impact on the dirt layer will destroy the adsorption of dirt and the surface of the cleaning part on the one hand, and cause the dirt layer on the other hand. break away from the surface of the cleaning parts and disperse them into the cleaning solution. The vibration of air bubbles can also scrub solid surfaces. Air bubbles can also "drill" into cracks to vibrate, causing dirt to fall off. For greasy dirt, due to ultrasonic cavitation, the two liquids are rapidly dispersed and emulsified at the interface. When the solid particles are wrapped by the oil dirt and adhere to the surface of the cleaning piece, the oil is emulsified and the solid particles fall off. In the process of vibration, the cavitation bubbles will cause the liquid itself to generate a circulating flow, which is the so-called acoustic flow. It can make the surface of the vibrating bubbles have a high velocity gradient and viscous stress, and promote the destruction and shedding of the dirt on the surface of the cleaning parts. The high-speed micro-jet generated by ultrasonic cavitation on the surface of solid and liquid can remove or weaken the boundary dirt layer , Corrode the solid surface, increase the stirring effect, accelerate the dissolution of soluble dirt, and strengthen the cleaning effect of chemical cleaning agents. In addition, the ultrasonic vibration causes a large vibration speed and acceleration of the particles in the cleaning liquid, and also makes the dirt on the surface of the cleaning parts subject to frequent and intense impacts.
       Because the ultrasonic wave will generate low pressure area and high pressure area during the transmission process, and cavitation only occurs in the low pressure area. Therefore, the workpiece to be cleaned needs to vibrate up and down in the ultrasonic wave, so that each area on the workpiece passes through the low pressure area to obtain the cleaning effect of "mini brush". The transmission speed of ultrasonic waves in water is 1500m/s. Assuming that the frequency of ultrasonic waves is 30000Hz, the wavelength of ultrasonic waves used is λ=speed/frequency=1500/30000=0.05m=5cm
       Therefore, if the ultrasonic wave of 30000Hz is used, the vibration distance of the workpiece should not be less than 5 cm. For other frequencies of ultrasound. The vibration distance can be calculated in the same way. In pure chemical immersion cleaning, the cleaning solution first dissolves the contaminants on the outermost surface of the workpiece, and gradually penetrates and dissolves into the pollution layer. This saturated layer isolates the fresh chemical cleaning solution from the deep contaminants and prevents the cleaning solution from continuing to dissolve the deep contaminants. If this saturated layer cannot be destroyed and removed, the cleaning will stop. For relatively dirty workpieces, it is difficult to thoroughly clean the workpiece by pure immersion cleaning. Using the "micro brush" of ultrasonic waves, the dissolved saturated layer on the surface can be destroyed. The new chemical agent reaches the deeper pollution layer and continues to dissolve. The ultrasonic wave then continues to destroy the newly formed dissolved saturated layer. In this way, the cleaning continues. Go down until the workpiece is cleaned.
3) Rinse
       The purpose of rinsing is to thoroughly clean the cleaning fluid or other dirt remaining on the workpiece, so that the workpiece is cleaner before drying. Residues on the workpiece will be difficult to clean after drying. in the industrial field. Usually deionized water is used for rinsing, and deionized water is used for rinsing instead of tap water. It can avoid impurities and pollutants in tap water remaining on the workpiece. However, deionized water is highly aggressive and can corrode the workpiece. Therefore, a certain amount of rust inhibitor must be added to deionized water before it can be used to rinse the workpiece. To prevent the workpiece from being rusted during the rinsing and drying process.
4) Drying
      The cleaned workpieces are generally dried in an oven, which includes a box body, a drainage pipeline, a heating system, an exhaust system and a temperature control system. The boiling and vaporization temperature of water is 100°C, so the baking temperature must be greater than 100°C, preferably between 110°C and 130°C, so that the water can be quickly evaporated to dry the workpiece. After drying, the temperature of the workpiece is too high and it takes a long time to cool down.
       Before the vacuum coating machine coats the workpiece, it must be strictly arranged to clean the workpiece, and the workpiece is cleaned to ensure the yield of the workpiece in the later stage.