The melt temperature is important, and the injection cylinder temperature used is only a guideline. The melt temperature can be measured at the nozzle or using the air jet method. The temperature setting of the injection cylinder depends on the melt temperature, screw speed, back pressure, injection volume and injection molding cycle. If you have no experience processing a particular grade of plastic, start with the lowest setting.
For ease of control, the shot tank is divided into zones, but not all are set to the same temperature. If operating for long periods of time or at high temperatures, set the temperature in the first zone to a lower value, this will prevent premature melting and shunting of the plastic. Make sure the hydraulic oil, hopper closure, mold and shot cylinder are at the correct temperature before starting injection molding.
The melt temperature plays a major role in the flow properties of the plastic injection parts melt. Since the plastic does not have a specific melting point, the so-called melting point is a temperature range in a molten state. The structure and composition of the plastic molecular chain are different, so the impact on its fluidity is also different. Rigid molecular chains are obviously affected by temperature, such as PC, PPS, etc., while flexible molecular chains such as PA, PP, PE, etc. have no obvious fluidity by changing the temperature, so the reasonable injection temperature should be adjusted according to different materials.
Some plastic injection molding materials require higher mold temperature due to high crystallization temperature and slow crystallization rate. Some plastic materials require higher or lower temperature due to the control of size and deformation, or the need for demolding. For example, PC generally requires more than 60 degrees. In order to achieve better appearance and improve fluidity of PPS, the mold temperature sometimes needs to be above 160 degrees, so the mold temperature has an important role in improving the appearance, deformation, size, and plastic mold of the product.
The melt overcomes the resistance required to move forward, which directly affects the size, weight and deformation of the product. Different plastic products require different injection pressures. For materials such as PA and PP, increasing the pressure will significantly improve the fluidity. The injection pressure Size determines the density of the product, i.e. the appearance gloss. It does not have a fixed value, and the more difficult it is to fill the mold, the higher the pressure of the injection molded part.
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