Among the factors affecting precision plastic injection, the mold is the key to producing precision plastic products that meet the quality requirements. The mold design will directly affect the quality of plastic products. Since the size of the mold cavity is obtained from the required size of the plastic product and the shrinkage rate of the material used, the shrinkage rate is a value within a range by the plastic manufacturer or the engineering plastics manual recommendation. It is not only related to the gate form, gate location and distribution of the mold, but also to the crystal orientation (anisotropy) of engineering plastics, the shape, size of the plastic product and the distance and location of the gate.
The main factors affecting plastic shrinkage include thermal shrinkage, phase transition shrinkage, orientation shrinkage, compression shrinkage and elastic recovery.
These factors are related to the molding requirements or operation of precision plastic injection products. Therefore, the designer of the mold must have rich experience in design and injection molding, and consider the connection between these factors and injection requirements and their apparent factors, such as injection pressure and cavity pressure and filling speed, injection melt temperature and injection mold temperature, mold structure and gate form and distribution, as well as gate cross-sectional area, product wall thickness, content of reinforcing fillers in plastic materials, crystallinity and orientation of plastic materials and other factors.
The influence of the above factors is also different due to different plastic materials, or other molding requirements such as temperature, humidity, continuous crystallization, and changes in the injection molding machine after molding.
Because the injection molding is a process of converting plastic from solid (powder or pellet) to liquid and back to solid. From the pellets to the melt, and then from the melt to the product, the process is affected by temperature field, flow field and density field in the middle.
Under the combined effects of these fields, different plastics (thermoset or thermoplastic, crystalline or amorphous, reinforced or non-reinforced, etc.) have different polymer structure morphology and rheological properties. The above factors will affect the precision plastic injection of plastic products.
Feman Tooling Co., Limited specializes in the manufacture and design of plastic and die-casting molds, and can provide a full range of mold manufacturing services, including design, prototype sample making, mold making, revisions and modifications, accessory JIGs and fixtures, plastic mold production with 250T capacity, and precision parts manufacturing. If you have any needs, please feel free to contact us.
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