Plastics are a material commonly used for goods across a variety of industries. Toys, medical devices, tools, and more are all made from plastic. To produce a plastic part, it must be manipulated to the shape desired using a method called plastic injection molding. This highly efficient process can make parts in many sizes and shapes and can replicate the same part multiple times using the same mold.
Injection Molding Process Steps
Injection molding is one of the most common manufacturing processes used to produce plastic goods. It is in high demand because the same part can be reproduced thousands of times. To begin the process, a three-dimensional CAD model is completed by a skilled design engineer. A plastic mold maker will then make the tool or mold that will be added to the injection molding machine. This mold is typically made from aluminum, steel, or alloy. Since plastic will shrink when cooled, the mold is made to account for shrinkage and ensure the part meets the exact specifications. The selected material begins as a plastic pellet that is then fed into an injection molding machine. The pellets make their way through a heated chamber where they are melted, compressed, and then injected into the mold cavity. Once the part cools, the two halves of the mold open to eject the part. The machine then resets to begin the process again.
Injection Mold Components
The injection mold is made from steel, aluminum, or alloy. These metal molds can be used thousands, sometimes millions of times. The injection mold has two parts, one half of the mold is the “best” side while the other half is the core side which will have some visual imperfections from the injector pins. An injection mold will also include support plates, ejector box, ejector bar, ejector pins, ejector plates, sprue bushing, and a locating ring.
Different Plastic Molding Processes
Not every good produced requires just a single plastic part. The plastic molding process can be adjusted to accommodate different and complex needs:
- Multi-cavity or family molds – The mold is produced to produce multiples of the same part using a single mold. Therefore, it has two or more cavities.
- Overmolding – A previously injection molded part is re-inserted into the injection molding machine as a second layer is added using a different material. This is useful when two different textures are desired. For example, a power tool with a grip.
- Insert molding – Metal, ceramic, or plastic pieces are inserted into molten thermoplastic. For example, metal inserts are added to a plastic piece so it can be attached to another part.
- Co-injection molding – In this process, two different polymers are sequentially or concurrently injected into a cavity.
- Thin-wall molding – A form of injection molding that focuses on shorter cycle times and higher productivity to produce thin, light, and cheap plastic parts.
- Rubber injection – Using a process similar to plastic injection molding, rubber is injected into a mold and placed under a higher pressure per square inch of cavity surface than plastic.
- Low-pressure plastic injection molding – As implied by the name, plastic parts are produced at lower pressures. This is particularly useful for jobs that require an encapsulation of delicate parts, such as electronics.
- Based on the specifications of your project, there is an injection molding method that can make your design a reality. For more information on plastic injection molding, contact ICOMold today. Our team of experts can assist you with your plastic injection molded project. Call us at 419-867-3900 or request an instant quote.