MoldingIt’s widely known that plastic injection molding can consistently produce thousands or even millions of plastic components or products for OEMs, aftermarket suppliers, packaging companies, and consumer goods manufacturers. Plastic injection molding has the ability to produce a wide variety of products varying in size, complexity, and composition. Applications for this highly repeatable and reliable process reach from automotive, HVAC and commercial filtration to markets such as appliance, lawn and garden, and medical.


How It Works

Once a part has been designed by an engineer, a toolmaker will craft a metal mold, usually out of steel or aluminum. The mold can have a single cavity or multiple cavities, precision-machined to form the desired part. Part and mold design can be very precise, even achieving (or exceeding) very tight tolerance of +/- 0.001 inches


A variety of polymers, including thermoplastics, thermosets, and elastomers, can be used for plastic injection molding. Pellets or granules of the selected material are heated in the barrel of an injection molding machine until the mixture is pliant enough to be injected into the mold. A ram- or screw-type plunger forces the correct volume or “shot” of material to fill the cavities under pressure while the two halves of the mold are clamped tightly together. The material cools and hardens into the shape of the part and is then removed from the opened mold so the process can begin again.

8 Benefits of Plastic Injection Molding

Plastic injection molding reliably creates a high volume of consistent, high-quality units, and there are several other compelling reasons to consider the process:

  1. It enables complex metal to plastic conversions, lowering overall part costs by reducing several machining operations into a single molding process.
  2. Plastic components are lower in weight than machined or cast metal parts.
  3. When plastic can be used instead of metal, corrosion is no longer an issue.
  4. Plastic injection molds allow greater design freedom for parts, because they allow the addition of radii or soft edge areas that would require extra machining (at an additional cost) in metal parts.
  5. Another element of design freedom is the ability to create highly detailed parts with complex geometry. Because the plastic material is pushed into the mold under high pressure, it fills the cavity completely and is pressed against the mold harder than in other molding processes. The plastic will thereby conform to even tiny, intricate shapes and details within the mold.
  6. It is also possible to combine different materials into the same part for greater utility with fewer assembly processes. With 2 shot molding, you can use a hard and a soft plastic to create a sealing edge or soft-touch edge, or use two different colors. Insert molding allows a non-plastic component to be incorporated, such as a metal screw built into a plastic cabinet knob.
  7. The plastic injection molding process involves a high degree of automation, which can provide significant savings in production costs. Many of the steps can be completed by the machines or robotics controlled by a single operator, reducing labor costs and overhead. The process can also be performed more quickly and efficiently, increasing production output.
  8. There is little to no material waste generated by this process, as leftover scrap plastic can be re-ground and reused.


Plastic injection molding reliably produces parts and components economically and efficiently. It also gives you a range of material and design options and produces parts that can reduce the overall cost to produce your product and, by decreasing weight of equipment or a vehicle, reduce costs associated with its use. It’s time to reevaluate your processes and see how plastic injection molding can benefit your company.


Viking Plastics has more than 45 years of experience with plastic injection molding, and our team of experts offers knowledge from a variety of molding and manufacturing backgrounds. Request a quote or contact us to learn more.