The vacuum state means the environment that supports the operation of the vacuum coating machine, especially the equipment that requires high vacuum. Usually, we need to reach a high vacuum degree and the function of the suction system is indispensable, but in addition to the suction system, there is another important point in the operation of vacuum coating machine, the degassing of the workpiece.
Some workpieces have a lot of gases and moisture inside. These substances will be discharged into the vacuum chamber when the equipment is heated, which reduces the degree of vacuum, and even worse, some gases have toxic components and directly damage the internal mechanical structure of vacuum chamber to causes the equipment not to operate normally.
In addition, in the process of coating, due to the heating and expansion of the gas in the workpiece, it is easy to crack the film that has already been plated. The probability of this case depends on the physical properties of the workpiece itself, such as plastics which is easily inflated the probability is relatively high. For hard metals, it has a relatively low probability. Therefore, degassing of workpieces is necessary.
The commonly-used degassing method of the workpiece is baking. The gas and moisture in the workpiece are discharged through heating. Before the coating, the workpiece is heated while pumping. When the moisture and gas in the workpiece are released due to heating, they will be pumped out together with the gas in the vacuum chamber by vacuum pumps.
Different gassing measures are taken for different workpieces to effectively control the internal gas and moisture emissions of the workpiece and then improve the stability and uniformity of the coating.