What Is The Exhaust Injection Tooling

- Nov 10, 2016-

  At this time of the rapid development of the injection molding processing industry, make people of all kinds of plastic products surface quality and dimension precision demand is higher and higher, especially in different engineering technology as pure structure parts used in plastic products, to meet the use of different physical properties and mechanical properties, main requirements or product compact structure, firm welding, the intensity is high, the internal stress is small. But in the process of injection mould test, and then adjust the parameters of the injection molding process, the products are not often arise filling, high internal stress, surface streamline various phenomena, such as the main reason is that the mold is a problem with the exhaust.
  In mould for plastic injection processing, mold inside of various gas mainly has the following several sources and reference: there are in the mold and gating system of the air; Plastic raw material is contained in the water evaporation in the injection temperature of water vapor; Gas produced by high temperature plastic decomposition; Some in the injection molding of plastic additives volatilize or some of the thermosetting plastic forming crosslinking reaction generated in the process of gas. At the same time to ensure that the process of injection molding to complete mold release, reduce the forming defects of products, we will consider how to improve the quality of the injection process at the same time, also must pay attention to the mould excreting excess gas system design.
   In the process of injection mold, such as mold venting is not good, the gas is compressed in the cavity will produce a lot of back pressure, greatly hindered the normal rapid molding of plastics melt and make it difficult to injection molding; Will force increasing injection pressure at the same time, the holding time increase, the molding cycle extended, the production efficiency is also constantly reduce the injection molded parts. Sometimes the corrosive gas in the cavity surface fouling formation, reduce the life span of the mould under normal use.
   In the process of injection molding machine for plastic molding, in order to keeping the liquidity of the molten plastic in the best state, so must increase in the temperature of the molten plastic and injection pressure, but also because of such products with the pressure and increase of residual stress and the product around the possibility of buckling and plastic cracking also
increases. For mould exhaust under normal circumstances, the injection speed can be improved, filling and pressure can be easy to achieve the best state, no extra increase the temperature of the cylinder and the nozzle. Such products small residual stress, warping deformation is small.

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