8 things you need to know about plastic injection molding

As we all know, plastic injection molding can consistently produce thousands or even millions of plastic parts or products for OEMs, aftermarket suppliers, packaging companies and consumer goods manufacturers. Injection molding has the ability to produce products of various sizes, complexities and compositions. Applications for this highly repeatable and reliable process range from automotive, HVAC and commercial filtration to markets such as appliance, lawn and garden, and medical.

How does plastic injection molding work?
Once the part is designed by the engineer, the toolmaker will create the metal mold, usually made of steel or aluminum. Molds can have a single cavity or multiple cavities that are precision machined to form the desired part. Part and mold design can be very precise, even achieving (or exceeding) tight tolerances of +/- 0.001 inches.

A variety of polymers, including thermoplastics, thermosets, and elastomers, can be used for injection molding. Pellets or granules of the chosen material are heated in the barrel of an injection molding machine until the mixture is flexible enough to be injected into the mold. A plunger-type or screw-type plunger forces the correct volume or "shot" of material to fill the cavity under pressure while clamping the mold halves tightly together. The material cools and hardens into the shape of the part and is then removed from the open mold to begin the process again.

8 Advantages of plastic injection molding
Plastic injection molding reliably creates large numbers of consistent, high-quality units, and there are several other compelling reasons to consider the process:

1. It enables complex metal-to-plastic conversions, reducing overall part cost by reducing multiple machining operations into a single molding process.
2. Plastic parts are lighter in weight than machined or cast metal parts.
3. When plastic can replace metal, corrosion is no longer a problem.
4. Injection molds allow greater design freedom for parts as they allow adding radii or soft edge areas which require additional machining (extra cost) in metal parts.
5. Another element of design freedom is the ability to create highly detailed shapes with complex geometries. Because the plastic material is pushed into the mold under high pressure, it completely fills the mold cavity and is more pressed against the mold than other molding processes. As a result, the plastic will conform to even tiny, complex shapes and details within the mold.
6. It is also possible to combine different materials into the same part using fewer assembly processes for greater utility. With 2 injection molding, you can use hard and soft plastic to create a sealed edge or a soft touch edge, or use two different colors. Insert molding allows non-plastic parts to be fitted, such as metal screws built into plastic cabinet knobs.
7. The injection molding process involves a high degree of automation, which can significantly save production costs. Many steps can be performed by a single operator-controlled machine or robot, reducing labor costs and overhead. The process can also be performed more quickly and efficiently, increasing yields.
8. Almost no material waste is produced through this process, as the remaining waste plastic can be reground and reused.

Custom injection molding can cost-effectively produce parts and components. It also provides you with a range of material and design options and produces parts that reduce the overall cost of producing the product and, by reducing the weight of the equipment or vehicle, the costs associated with its use. Now is the time to re-evaluate your process and see how injection molding can benefit your company.

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