Mould injection goods are widely seen in daily life, plastic seals are one of the garments used in garment industry. Injection molding machines consist of a material hopper, an injection ram or screw-type plunger, and a heating unit. They are also known as presses, they hold the molds in which the components are shaped. Presses are rated by tonnage, which expresses the amount of clamping force that the machine can exert. A voltage applied between tool and mold causes spark erosion of the mold surface in the inverse shape of the electrode.
 

Standard machining, in its conventional form, has historically been the method of building injection molds. With technological development, CNC machining became the predominant means of making more complex molds with more accurate mold details in less time than traditional methods. Changes to a hardened mold by conventional drilling and milling normally require annealing to soften the mold, followed by heat treatment to harden the plastic seals again. The total clamp force needed is determined by the projected area of the part being molded. The required force can also be determined by the material used and the size of the part; larger parts require higher clamping force.
 

When filling a new or unfamiliar mold for the first time, where shot size for that mold is unknown, a technician setter may perform a trial run before a full production run. Gate freeze off time can be determined by increasing the hold time, and then weighing the part. When the weight of the part does not change, we then know that the gate has frozen and no more material is injected into the part. Gate solidification time is important, as it determines cycle time and the quality and consistency of the plastic seals, which itself is an important issue in the economics of the production process. Holding pressure is increased until the parts are free of sinks and part weight has been achieved.