Plastic injection molding is the process of producing plastic parts by passing the molten form of plastic into mold materials that are shaped in the design of the desired final product. Injection molding can be used in the production of a variety of products other than plastic products. It can be used to produce items made from aluminum, glass, and several different materials. In the process of plastic injection molding, the raw material is heated then passed through molds then cooled to take the desired shape before being assembled. In this post, we look at the essential aspects of the injection molding process.
Perhaps the most critical aspect of plastic injection molding and other forms of injection molding is the process of mold design. There are different parts of the mold that have to be considered when coming up with the mold design. These parts include the windows, the gates, and vents, among others. Other features to consider during mold design include;
Side actions- these are the unique features that are designed into the mold especially when the product design is intricate. Such unique features include; lifters, screwing actions, collapsible cores, and slides, among others.
The type of mold- there are three types of molds, which include a single cavity mold, a multi-cavity mold, and the family tool mold.
The Molding Process
The first step of the plastic injection molding process is collecting the raw materials needed. This comes after the feasibility stage where the type of material to be used is determined. Once the raw materials have been collected, the next step would be to heat the elements at a different temperature to change them into a molten form.
The next step then is the injection process. Here, the melted or the molten plastic (or any other raw material is injected into the mold through the process called injection. During this process, the material enters the mold displacing the air in the spaces through the vents found in the injection pins. Some of the air is also ejected through the parting lines on the mold. To endure that the mold is adequately filled with molten plastic, parts of the mold like vents, runners, and gates come in handy owing to their design.
After injection, the raw material, while adequately filled into the mold is then cooled. The cooling process is timed to the precise amount required to change the raw material from molten to solid form. The molding machine comes typically with internal heating and cooling elements that maintain a constant temperature. As the materials cool down in the mold, screws on the barrel retract, and plastic resin is drawn into the barrel from the hopper.
The final step is the ejection of the final products which happens as the erector rods of the machine move the pins forward.
The other term for mold designing in injection molding is tooling. While injection molding may be efficient in several ways, the whole process is determined by the quality of the tooling.