Custom Injection Molding Processes

The process of injection molding is a manufacturing process for producing parts and components from thermoplastic materials. Injection molding is a simple process: plastic materials are fed into a heated chamber, mixed, and then piped into a mold cavity where it cools. As it cools it hardens to the shape. Industrial engineers design the product and mold or toolmakers create the mold itself, which is usually made out of metal and precision manufactured to the spec. Injection molding is widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars. Some plastic injection molding companies can do simple injection molding to value-added campaigns like mold takeover, mold design or other types of molding like co-injection molding, in-mold decoration, insert molding, and assembly.

Mold Design and Injection Process:
The first step for injection molders is to design the mold to specifications. A mold consists of two primary components, or plates, the injection mold half and the ejector mold half. Plastic resin enters the mold through a sprue in the injection mold, which allows molten plastic to flow from the barrel into the mold. The plastic resin or granules are moved forward by a screw-type plunger into a heated chamber, where it is melted.

As the plunger advances, the melted plastic is forced through a nozzle that rests against the mold, allowing it to enter the mold cavity through a gate and runner system. The mold remains cold so the plastic solidifies almost as soon as the mold is filled. In the cavity the hot plastic resin liquid will cool and form the shape of the mold.

Calculating the Efficiency of a Company's Injection Molding Process:
The injection molding process (or cycle) starts when the mold closes and is followed by the injection of the resin into the mold cavity. Once the cavity is filled, a holding pressure is maintained to compensate for material shrinkage. Next, the screw turns which feeds the next shot to the front screw. This causes the screw to retract as the next shot is prepared. Once the part is sufficiently cool, the mold opens and the part is ejected. The time this process takes to complete is calculated by adding twice the mold open and close time to the ejection time and the cooling time. The injection time is calculated by dividing mold size by the flow rate. The closing and ejection times vary depending on the quality of the machine and the size of the mold.

There are many custom products that custom injection molding companies can handle for their customers. This is possible if the company has the numerous capabilities and certifications that a company needs to provide certain solutions to their customers. Some of these certifications are Dairy, NSF, UL, automotive, consumer products, and O.E.M. products.