Among all factors affecting injection molding, time, temperature and pressure are the most important one. We have talked about time and temperaturethese two factors affecting injection molding in another two passages. In this passage, we will talk about pressure this important factor affecting injection molding.
As a factor affecting injection molding, pressure can affect injection molding from three aspects: plasticizing pressure, injecting pressure and holding pressure.
Plasticizing pressure
Plasticizing pressure is also named screw backpressure, which refers to the pressure given to melt plastic when the screw rolls. Plasticizing pressure, one of factors affect injection molding can be controlled by the relief valve in hydraulic system.
In daily operation, on the premise that the quality of plastic products is ensured, the plasticizing should be as small as possible. The specific pressure should vary with different plastic.
Injecting pressure
Injecting pressure means the pressure given to the melt plastic by the head of screw when the screw id moving forward, which can be controlled by the control system of injection machine.
If the injection pressure is very high, the flow ability of plastic is increased. Problems like overflowing, flashing will arise very easily. But if the injecting pressure is very low, the flow ability of plastic is decreased; problems like bubble, void will arise.
Holding pressure
When the cavity is full, people may continue to giving pressure to the melt plastic in cavity. This pressure is called holing pressure. Holding pressure is also a very important factor affecting injection molding. If the hold pressure is too high, there will be problems like over flowing and flash. If the hold pressure is too low, there will be problems like void.
Times, temperature and pressure are three very important factors affecting injection molding. Want to know more about plastic injection molding, please contact Dakumar.
Edited by Miss Cina
E-mail: dkm@dakumar.com
Skype: sinomould-13
MSN: dkm@dakumar.com
