How Injection Molding Works
Plastic is an amazing material to work with. Plastic can be formed into a variety of products from the simple pocket comb to electronics and even entire body panels for cars. Plastic is highly durable, structurally sound, and bets of all low cost. All of this makes plastic a very desirable product construction material and with the rise in demand for plastic products, so to has the demands on the plastics industry risen.
Most all plastic products are manufactured using a process called plastic injection molding. Simply defined injection molding is the process of adding material (usually in a liquid state) to a mold and then cooling and removing the mold. This is custom injection molding in it’s simplest form. Think of a common toothbrush or comb for example, there isn’t a whole lot of detail to either of these products and they can be produced by using plastic injection molding services for a cost of pennies per unit. Even larger scale and more complex plastic products follow the basics of the injection molding process.
Injection molding all starts with the mold. In this industry the right mold really does make all the difference. Thousands to even hundreds of thousands of products can be produced from a single well designed mold. But without a mold no product can be produced at all. The bulk of the cost associated with creating a plastic product are dedicated to developing the mold. The cost to create a mold can be high, but the return on the investment is the ability to create large scale runs of a product for minimal costs. High design costs, low production costs.
Engineers are typically employed to design a plastics injection mold and then the design is handed off to a mold maker or tooling expert to create. Molds can be anywhere from a few inches in size to the size of large complex machines. The dimensions of the mold really depend on the product being molded. Molds are typically created from metals such as steel or aluminum. The mold itself needs to be crafted from a material that can support the injected material without melting, damaging, or compromising the integrity of the material or mold. That is why durable metals have long been the preferred choice for molds craftsmen.
The process of injection molding can be extremely complex depending on the needs of the project. However, there are basic elements that all injection molding projects must follow. First, resin or granular plastic is fed from a hopper into a heated chamber drum. The plastic pieces are progressed through the drum where it melts the grains into a liquid form, creating liquid plastic. The liquid plastic is then forced through the injection molder and out through a nozzle attached to the plastic mold. As the melted plastic enters the mold it compacts and builds a great deal of pressure to ensure the plastic fits the dimensions and design of the mold entirely. The mold is then screwed or clamped into place and the plastic cools and hardens inside.
Once the plastic is cooled the screws and clamps release the plastic is ejected from the mold. Molds are kept cold to reduce the time it takes the products to cool making the entire process take only a matter of seconds to complete. The end result is that new hairbrush, plastic soda bottle, or even the dashboard or your car. All of these products and more are created everyday thanks to the technology of custom injection molding.
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