Injection Molded Plastics
Plastics, because of their flexibility, cost and strength, are used in a wide variety of industrial, commercial, retail and domestic applications throughout the world. Molding plastics into a desired shape and form can be achieved in several different ways. Injection molding, as its name suggests, is where plastics are injected and molded into various shapes by injecting molten plastic into a mold under very high pressure. The mold is the inverse of the desired form. Due to the high temperature and the high pressure that the mold is exposed to, these molds are usually made of hardened steel or titanium.
The injection molding process involves six different steps and injection molding machines consist of three parts, which are the mold, the clamping units, and the injecting units. The molds are built in halves and they can be very simple, with one cavity, or they can contain several cavities and be quite complex. Complex molds can be quite expensive and sometimes cost over $100,000. However, if there is a high demand for a product the molds will easily make back their initial cost.
The clamping units of an injection molding machine are designed to hold the halves of the molds together while the plastic is injected and then cooled down. Most types of injection molding machines use plastics that are in the form of pellets which are poured into the machine’s injection unit. If the plastic needs to be colored it is added here. The pellets and colorants are then heated to the right temperature and thickness. Once the plastic has melted it is injected into molds by either screws or ramming devices.
The next part of the process is the dwelling phase in which pressure is applied to ensure that the cavities of the molds are filled to the top. After this the plastic cools down and then hardens. When you are ready to open the mold the two halves of the mold are taken from the plastic after it has cooled and hardened. The last phase of the injection molding process is called ejection. This takes place when the item is removed from the mold and any scrap plastic that is left over is saved for future use.
Injection molded plastics are used in a wide variety of industrial applications ranging from the automobile sector to the food processing industry. Care must be taken while the molten plastic is injected that the mold is completely filled, otherwise the plastic could develop cracks in it after it cools down. As stated, these molds are very expensive to manufacture, but they have a long lifespan and injection molded products can be manufactured at a high rate with a minimal need for labor.