Arc spraying mold molding process
Author: langfeng Time: 2017-11-08
Arc spraying mold molding process
(1) spraying model
Arc spraying mold is characterized by the sample as a benchmark, the mold cavity size, geometric accuracy depends entirely on the sample mode, sample design should be based on the shape of the product process to determine the shape and size requirements. In order to facilitate the stripping after spraying, the sample can be designed into a combination of modular structure. The company is located in:
Sample manufacturing a lot of material: gypsum, graphite, resin, ceramics, wood, metal, etc., can also be used directly for the product model to use.
(2) release agent, release agent
The use of arc spraying technology to produce molds, both require uniform and dense metal particles attached to the sample surface, but also requires the formation of the shell after the smooth and complete separation from the sample, but also in the spraying process to protect the model and The surface pattern can withstand the impact of spraying metal particles. At the same time, to withstand the spraying of high temperature and prevent heat transfer to the sample.
(3) spraying parameters
Arc power: arc power is determined by the power supply, it is the main factor affecting the quality of the mold cavity. Power is small, arcing difficult or broken arc, spraying the metal material can not melt well, affecting the bonding strength of the coating. Power is too large, spraying metal easily overheated, the surface of the metal oxide serious oxidation, reducing the mechanical properties of the spray coating. The use of zinc alloy spray molding material to the arc voltage 36V, arc current 110A more appropriate.
② spray distance: spray distance refers to the spray mold, the distance between the nozzle to the sample mode. Spray distance directly affects the quality of the spray coating. If the distance is too large, the temperature and speed of the metal particles impacting the sample surface will decrease, the kinetic energy decreases, the plasticity will be poor, the coating structure will be loose, the strength will decrease, and the deposition efficiency will decrease. Distance is too small, the spray layer temperature increases, the mold cavity prone to thermal deformation, affecting the accuracy of the mold. Through the test, the spray nozzle to the sample between the spray distance of 150 ~ 200mm is appropriate.
③ spray angle: spray angle refers to the arc spray forming nozzle gas flow axis and the sample is sprayed between the angle. This angle perpendicular to the sample surface is the best, the last resort, it should not be less than 45 °, otherwise it will have a "shadowing effect"
④ spray pressure: arc spray molding is the use of compressed air, the molten metal atomized into particles and spray to the surface of the sample. Therefore, the compressed air is required to have a certain steady pressure, and to ensure that the air dry and clean, through the test, we selected the air pressure of 0.5 ~ 0.6MPa.
⑤ fill the substrate: When the spray coating to form the shell, the use of matrix material filled with real, the shell for support and reinforcement. The choice of matrix material, mainly based on the working conditions of the mold and the spray layer of different materials, choose different materials and processes. Mold on the substrate material requirements, should have a certain strength, to meet the working condition of the mold force requirements, easy to shape. As the spray shell is formed, its shape is more complex, the matrix shape must be closely matched with the coating, therefore, the filling matrix must have the characteristics of easy forming, to have a certain degree of thermal conductivity and heat resistance, while its thermal conductivity and thermal expansion Coefficient should be similar to the metal spray coating, especially when the mold temperature is high, it should be noted.
⑥ inlaid metal parts: some parts of some molds have some special requirements, it is difficult to spray, you can use metal inserts. Sprayed metal inserts, after the sample is removed directly into the mold cavity part. These special parts are generally refers to the mold has a deep depression, raised or ribs and other structures, and the height of the raised or recessed greater than its width, these areas should be placed inserts. For some of the larger force, heavier wear parts of the mold, but also the use of metal inlay approach to improve die life. Insert the installation shown in Figure 4.
According to the working conditions of the mold, the force situation and other factors, choose different inserts materials, such as steel, cast iron, aluminum, zinc alloy, copper and so on.
⑦ assembly test mode: arc spray to form a mold cavity, filled with real after the sample from the cavity projectile and clean up to meet the requirements, the appropriate assembly of the assembly, you can form a complete mold.
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