With shipments exceeding $300 billion dollars annually, plastics manufacturing is one of the largest manufacturing sectors in our nation today. Of the various processing techniques, injection molding is one of the most common and economical methods of converting raw plastic into finished goods. Usually, in the long run, there are considerable quality and cost advantages associated with injection molding. While the initial cost of injection molding can be high due to tooling costs, the individual cost per part is often a fraction of what it would cost in comparison to manufacturing the same product by another method.

The injection molding machine, or IMM, is at the core of the injection molding process. Generally speaking, an IMM consists of two major components; these components include a clamp unit where the mold is mounted, and an injection unit where the raw material is heated and mixed prior to being injected into the mold. Processing begins by inputting values and tolerances in the machines control system, such as: times, pressures, temperatures, and speeds. Processing knowledge and experience are critical in determining the proper parameters for quality and efficiency.

Before production begins, the mold is clamped into the machine and the necessary auxiliaries are hooked up, i.e. temperature controllers, hydraulic cores, etc. The mold is then inspected and dry cycled, to ensure proper set-up and function. After test shots are run to verify quality, production is ready to begin.

At the beginning of each cycle, the clamp unit closes the mold and builds tonnage, keeping the mold locked during the injection stage. It is essential that a machine with the proper tonnage be selected in comparison to the size of the mold and the injection pressures to be used. Otherwise, the mold can be blown apart from the extreme pressures produced during injection. When the clamp is closed, the screw in the injection unit pushes forward and shoots the molten material into the mold. Once in the mold, continual pressure is applied to pack and hold the material firmly in place while it solidifies. While the material in the mold is cooling, the screw rotates and retracts drawing more material into the barrel in preparation for the next shot. After the part has cooled, the clamp unit opens, ejects the finished parts, and the cycle begins again. This entire process can range from roughly 5 seconds to over a minute, depending on the part size and type of material being used in the process.