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The key points when design car precision plastic parts moulds
Jan 24, 2018

         Car plastic zero most used injection molding, because the plastic itself is of high precision design, make the plastic parts can't adopt the conventional injection molding, precision injection molding process technology must be used.Precision plastic parts to ensure that the car's performance, quality and reliability, the injection molding of high quality and meet the requirements of the product design of plastic products, plastic materials, injection molding equipment and must be constantly to improve the mold and injection molding process.

The main factors that influence the precision injection molding.

The precision injection molding is based on the precision of the injection molded products, namely the size tolerance, shape tolerance and surface roughness of the products.There must be many related conditions for precision injection molding, and the most essential factors are plastic material, injection mold, injection molding process and injection molding equipment.Design of plastic products, should be first selected engineering plastic material, and can perform a precision injection molding engineering plastics and must choose those high mechanical properties, dimension stability, good creep resistance, environmental stress cracking resistance of the material.Next, according to the selected plastic material, finished product dimension precision, weight, quality requirements and the expected mold structure to select suitable injection molding machine.In the process of processing, the factors that affect the precision injection molding products mainly come from the precision of the mould, the shrinkage of the injection molding, and the range of environmental temperature and humidity variation of the products.

In precision injection molding, the mould is one of the key to obtain the precision plastic products which meet the quality requirements. The mold of precision injection molding should meet the requirements of product size, precision and shape.But even if the precision and size of the mould are consistent, the actual size of molded plastic products will be different due to the difference in shrinkage.Therefore, it is very important to effectively control the shrinkage rate of plastic products in precision injection molding technology.

Mould design is reasonable or not will directly affect the plastic shrinkage rate, due to the mold cavity dimension is estimated by the plastic product size and shrinkage rate is obtained, and the shrinkage is or manual of engineering plastics as recommended by the plastic manufacturer of a range of values, it not only with the mold gate forms, gate location and distribution, and the crystal orientation of engineering plastics.

The shape and size of plastic products are related to the distance and location of gate.Influence mainly include thermal contraction of plastic shrinkage rate, phase change shrinkage, orientation, compression contraction with factors such as elastic recovery, and the influence factors and precision injection parts molding conditions or operating conditions.Therefore, these factors must be considered when designing the mold and injection molding conditions and the relationship between apparent factors, such as injection pressure and cavity pressure and mold filling speed, melt temperature and mold temperature, injection mold structure and gate forms and distribution of products as well as the gate area, wall thickness, plastic materials, plastic materials content of reinforcing filler in the impact of factors such as crystallinity and orientation.The influence of the above factors is also different due to different plastic materials, other molding conditions such as temperature, humidity, continuous crystallization, internal stress after forming, and the change of injection molding machine.

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