Three elements of plastic injection molding

The plastic injection molding processing method is a process in which a certain amount of molten plastic is injected into a closed mold cavity at high pressure, cooled and solidified in the mold, and then opened and taken out.

How to obtain good injection quality and shorten the process time in this process is the goal pursued by the plastic injection industry.

Plastic injection molding has three elements:

  1. Raw materials
    Plastic raw material – resin dominates the temperature (thermal properties) and time (rheological properties) of the injection process. Different resins have different melting points, different shrinkage rates, and different melt flow indexes, and these will affect the parameters during injection.

In addition, different resins also have different tensile strengths, different impact strengths, and different elastic coefficients, and these factors will affect the structural strength and elasticity of molded products.

  1. Injection molding machine

The injection molding machine can be divided into three parts:

Hopper mechanism: The hopper can be used as a buffer zone and store a certain amount of resin plastics to avoid insufficient supply. The hopper also provides plastic preheating and drying, because some plastics are very sensitive to moisture, which may easily cause degradation and embrittlement of the finished product.
Injection mechanism: melt the resin, mix the chain and provide kinetic energy to inject a certain amount of resin into the mold under high pressure.
Clamping mechanism: provide a powerful mechanism to close and open the model and the power to eject the molded product.
Control system: According to different resin raw materials, control various parameters during injection molding, such as injection temperature, injection rate, injection pressure, clamping force, etc.

  1. Mold
    It is the place where plastic products are molded. There are injection runners, gates, and mold cavities, as well as heating, cooling, and ejection mechanisms to facilitate product molding and cooling and demoulding. This requires a CNC machine to be processed into a production-ready mold through a series of processes.