The plastic injection molding process is responsible for the production of millions of everyday parts, but the ins and outs of how the process works are something most people aren’t usually familiar with.
In this blog, we’ll review the plastic injection molding process, the key stages, and why each step is important to the final result of the plastic part.
First things first: What is plastic injection molding?
Plastic injection molding is a process where molten plastic is injected into a mold cavity (tooling), cooled, and then released to produce a finished part. It requires expensive machinery and tooling, as well as trained staff to monitor the process, and is typically suited for high-volume production with parts that require consistent quality.
There are three main features necessary for a successful plastic injection molding process: high-quality tooling, the correct material for the plastic parts’ intended use, and a well-maintained and operated injection molding machine.
The Injection Molding Process
When it’s time to begin the injection molding process, your design and tooling are already finalized along with your material selection, and you are now ready for production. Here is how we take a plastic pellet and turn it into a plastic part:
1. Clamping
Before the molten plastic is injected, two halves of the tooling (also referred to as a mold) are pressed tightly together in the injection molding machine. It’s important to keep the mold securely closed during the injection process, as it helps prevent defects, which can become costly.
2. Injection
Plastic pellets, which can be derived from a range of different plastic materials, are inserted into the machine. They’re heated until they become molten, and the melted plastic is then injected into the mold cavity. This is where the part begins to take shape.
3. Packing and Holding
Once the mold cavity is completely filled, the machine applies pressure to fully pack the cavity and offset any shrinkage from the plastic cooling. The packing and holding process helps the plastic part keep its intended shape and dimensions.
4. Cooling
Cooling is where the plastic solidifies inside the mold, finalizing into the exact shape of the part. The timeline of this step can vary depending on the material used and the thickness of the part, often being one of the main factors affecting cycle times. However, ensuring the plastic part has completely cooled is essential.
5. Ejection
Once the part is cooled enough to maintain its shape, the tooling clamp is released, and the finished part is pushed out of the machine. Once the part is out, the tooling is closed again, and the next cycle starts.
6. Inspection and Finishing
This is where a highly trained team is important, because the last step is checking for quality to ensure the part meets specifications. Any trimming, assembly, or other finishing operations are completed here before the parts move onto packaging and delivery.
Why Each Stage Matters
Injection molding is a repeatable process with an emphasis on consistency, but sometimes small variations that occur along the way can affect the final part. Slight changes in temperature, pressure, or cooling might impact a part’s dimensions and appearance, which is why quality control is so important — whether it’s the first part ejected or the 500th part.
Trained technicians and consistent quality control checks are essential throughout all stages of the production run. From the maintenance of your tooling and the injection molding machine to the understanding of material selection and how that impacts results, a reliable injection molding manufacturer ensures each stage of this process is given the attention it requires.
Conclusion
Each stage of the plastic injection molding process comes together to create a high-quality plastic part. Beginning with design and tooling, the actual injection process can then be completed repeatedly to provide plastic parts that continuously perform as intended.
Working with a plastic injection molding company that understands the importance of preparation, execution, and quality control is essential to receiving plastic parts that perform. At Camcar Plastics, our team guides you through every step, from design to delivery, so your plastic parts are made with quality and care. Contact us today to discuss your project or learn more about our injection molding services.
