Analysis of the influence of precision injection mold
Mould designers, must have a rich experience in design and injection molding, these factors must be considered and the relationship between injection molding conditions and its apparent factors, such as: injection pressure and cavity pressure and the 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 effects of the above factors are also different due to different plastic materials, or other molding conditions such as temperature, humidity, continuing crystallization, molding injection molding machine changes.
Among the related factors that affect precision injection molding, mold is the key to obtain precision plastic products that meet the quality requirements.Whether the mold design is reasonable will directly affect the quality of plastic products.
Due to the mold cavity dimension is made by plastic products required size and shrinkage of the materials used, and the shrinkage rate is often 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 with the crystal orientation of engineering plastics (anisotropic), plastic products shape, size and the distance to the gate position.The main factors affecting the shrinkage of plastics include thermal shrinkage, phase change shrinkage, orientation shrinkage, compression shrinkage and elastic recovery, and these factors are related to the molding conditions or operating conditions of precision injection molded products.
As the injection molding process is from solid (powder or pellets) to liquid (melt) to solid (products) the transformation process.From the particle to the melt, and from the melt to the product, the intermediate through the temperature field, flow field and density field and so on.Under the combined action of these fields, different plastics (thermosetting or thermoplastic, crystalline or non-crystalline, enhanced or non-enhanced, etc.) have different polymer structures and rheological properties.The physical and mechanical properties, size, shape, precision and appearance quality of plastic products will be affected by the factors affecting the above "field".
In this way, the intrinsic relationship between the process factors and the polymer's performance, structure and plastic products can be expressed through the plastic products.The analysis of these internal relations is of great significance to reasonably draw up injection molding process, reasonably design and manufacture molds according to drawings, and even to reasonably choose injection molding equipment.
Precision injection molding is different from ordinary injection molding in injection pressure and injection rate.Precision injection molding often USES high - pressure or ultra - high - pressure injection, high - speed injection to obtain a small molding shrinkage.