Beijing – The exhausting is an important issue for the design of the injection molding especially in the fast injection molding which has more stringent requirements for exhausting capacity of the injection molder. Today, the best china injection molding manufacturer which website is www.duratecplastics.com would describe with you the exhausting of the injection molding.
The first factor the Duratec want to tell us is the source of the gas in the injection molder. First, there would be air in the gating system and mold cavity of the plastic injection molding . Second, it was said that some raw material would contain water which would be easy to be vaporized into steam at high temperature. Thirdly, as the molding temperature is too high, some decomposition of the unstable nature of the plastic could be generated and produced the gas. The additives volatile or another chemical in plastic materials would have certain reaction which would produce gases.
The second point the Duratec want to tell us is the hazard result of the exhaust. As we all know, the bad exhaust capability of the injection molder will give a range of hazards to other the quality of plastic parts and the mainly bad results are listed below. First, in the injection molding process, the melt will replace the gas in the cavity. If the gas could not be discharged in time, it will result in the difficulty in filling for the melt. This kind of situation would result in insufficient injection volume and the cavity cannot be filled. The poor formation of gas would form high pressure in the cavity and then it would cause causing pores, voids, loose tissue, crazing and other defects in a certain degree of compression for the plastic.
Since the gas has been highly compressed, this would make the cavity temperature rise sharply. Thereby, it would cause the surrounding has decomposition and burning which would result in partial carbonization and plastic burning phenomenon. It is mainly in the confluence of two shares of the melt and the flange at the gate. The gas in the cavity will reduce the filling speed and then it would has bad impact with the production efficiency.
The last we want to introduce you is the distribution of air bubbles in the plastic parts which have been produce by plastic molding.The main sources of gas in the cavity could be divided into three categories which are the accumulation of air in the cavity, gas from the decomposition of the raw material and raw residual water vapor evaporation. Due to different sources of bubbles generation, the position is different.
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