What are the Injection Process and Post-treatment of Plastic Parts for Injection Molding Service?

The injection molding process is the process of making semi-finished parts of a certain shape from molten raw materials through operations such as pressurization, injection, cooling, and detachment. And the plastic parts are easily damaged by other factors after injection molding.

The following is an introduction to the injection molding process and post-processing methods of injection molding services

Injection process

Post-processing

Injection process

First of all, the material is added to the hopper of the injection machine by adding granular or powdered plastic. Then plasticization, through the heating device of the injection machine, the plastic material in the screw is melted and becomes a plastic melt with good plasticity. The plasticized plastic melt is pushed by the plunger or screw of the injection machine, and then it enters and fills the mold cavity with a certain pressure and speed through the nozzle and the pouring system of the mold. Then the melt is kept under pressure to replenish the shrinkage.

After the melt fills the cavity, the melt is still kept under pressure for replenishment under the push of the plunger or screw of the injection machine, so that the melt in the barrel continues to enter the cavity to replenish the shrinkage need of the plastic in the cavity, and the melt backflow can be prevented. This is followed by cooling after the gate freezes, and after a period of time, the molten plastic in the cavity solidifies to ensure that when the mold is released the part has sufficient stiffness to not warp or deform. Finally, the mold is released and the part is cooled to a certain temperature, and the plastic part is pushed out of the mold by the push-out mechanism. The injection molding process of our injection molding service is carried out in strict accordance with the requirements.

Post-processing

Since plasticized or due to non-uniform crystalline plastics in the cavity, the uneven cooling, and orientation; or due to the influence of metal inserts or secondary processing of the plastic parts due to the reasons such as improper, the internal plastic parts inevitably some internal stress, resulting in plastic parts deformation or cracking during use. Therefore, we should try to eliminate these shortcomings. Our company's injection molding service attaches great importance to the post-processing methods of plastic parts to ensure the integrity of the plastic parts.

Annealing treatment

Annealing treatment is a heat treatment process in which the plastic parts are left in a heated liquid medium (or hot air circulation oven) at a fixed temperature for a period of time, and then slowly cooled to room temperature. The temperature should be 10 ° ~ 15 ° above the use temperature or 10 ° ~ 20 ° below the heat deflection temperature. The time is related to the plastic species and the thickness of the plastic parts can generally be calculated by about half an hour per millimeter. The effect is to eliminate the internal stress of the plastic part, stabilize the size of the plastic part, improve the crystallinity, stabilize the crystalline structure, and thus improve its elastic modulus and hardness. The hardness of plastic parts provided by our injection molding service is enhanced after the annealing treatment.

Humidification treatment

Humidification treatment is a post-treatment method in which the freshly demolded plastic parts are put into the heating medium to accelerate the moisture absorption and equilibrium rate. The temperature is 100~121℃ (the upper limit is taken when the heat deformation temperature is high, and the lower limit is taken vice versa). The purpose is to eliminate the residual stress; make the product reach the moisture absorption equilibrium as soon as possible to prevent the dimensional change in the process of use.

Team Rapid MFG Co., Ltd. provides injection molding services focusing on the processing process and excellent product properties.