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Four Key Points Affecting the Quality of Injection Mold

Posted by: Mu Ju 2021-11-02 Comments Off on Four Key Points Affecting the Quality of Injection Mold

1) plastic materials


The complexity of plastic material properties determines the complexity of injection moulding process. The performance of plastic materials varies greatly with varieties, brands, manufacturers and even batches. Different performance parameters may lead to completely different forming results.


2) injection temperature


The melt flows into the cooling cavity and loses heat due to heat conduction. At the same time, the heat generated by shearing may be more or less than the heat dissipated by heat conduction, mainly depending on the injection conditions. The viscosity of melt decreases with the increase of temperature. Thus, the higher the injection temperature, the lower the melt viscosity and the smaller the filling pressure required. At the same time, the injection temperature is also limited by the thermal degradation temperature and decomposition temperature.

3) mold temperature


The lower the mold temperature is, the faster the heat loss due to heat conduction is, the lower the melt temperature is, and the worse the fluidity is. This phenomenon is particularly evident when the injection rate is low.


4) injection time


The influence of injection time on injection molding process is manifested in three aspects:


  • Shortening the injection time, the shear strain rate in the melt will also be increased, and the injection pressure needed to fill the cavity will also be increased.


  • Shorten injection time, increase the shear strain rate in melt. Due to the shear thinning property of plastic melt, the viscosity of melt decreases, and the injection pressure needed to fill the cavity also decreases.


  • Shorten the injection time, increase the shear strain rate in the melt, increase the shear heat, and reduce the heat loss due to heat conduction. Therefore, the higher the melt temperature and the lower the viscosity, the lower the injection pressure needed to fill the cavity. As a result of the above three conditions, the curve of injection pressure required to fill the cavity presents a “U” shape. That is to say, there is an injection time at which the injection pressure is minimum.


PTJMould Industrial Company Limited, established in 2010, is a leading plastic injection molding manufacturer in China. PTJMould specializes in plastic mould production for household appliances, medical equipments, electronic equipments, safety equipments as well as monitoring system.

The company has over 15000 square metres factory. With plastic injection tooling divisions possessing different machinery and expertise, PTJMould offers tools from small and precise mobile phone parts to as big as automotive parts. Our tools are mainly exported to U.S.A., Europe, Japan and UK. PTJMould’s diversification strategy and full service has won compliment from customers all over the world.

Our mission is to provide our customers high quality moulding products and services. We aim to exceed our customers’ expectations of pricing, quality and on-time delivery. To achieve our mission, PTJMould:

  • Commits to continually improve employee skills and efficiency,
  • Provides our employees a clean and safe working environment,
  • Upgrades machine technology and support equipment through a strict maintenance program, and
  • Maintains customers’ tooling to its highest peak of performance

For more about custom manufacturer of plastic molding products,please visit https://www.plastics-moulding.com/


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