Learn More about the Process of Plastic Injection Molding

rubberDid you know that injection molding is the most commonly used manufacturing method for the production of plastic parts? Injection molding is mostly used for plastic housing, which is a thin-walled enclosure that’s used in an array of products, such as everyday household appliances, automotive dashboards, and consumer electronics. There are many advantages to injection molding, including excellent surface finish, good dimensional accuracy, high production rate, low labor cost, and most items are easily recycled.

The injection molding process requires the use of the following items:

  1. injection molding machine
  2. raw plastic material
  3. mold temperature control (water, electric heat or oil heat)
  4. tower or chiller system

The actual process cycle for injection molding is extremely short, typically between ten seconds and two minutes. It consists of the following four stages:

1. clamping – two mold halves are pressed together before the material is injected into the mold

2. injection – the plastic material is placed into the injection molding machine, and the material is melted through heat and pressure

3. cooling – the plastic inside the mold begins to cool and solidify into the desired part

4. ejection – after enough time has passed, the cooled part may be ejected from the mold, and once ejected, the mold can be closed again so that the cycle can be repeated

The cycle time can be shortened by reducing the wall thickness of the parts. Consistency, or all of the walls being the same width, can also help. If more support is required, ribs can be added rather than increasing the wall thickness. Another good tip is to reduce the amount of internal and external undercuts, as that will save on the overall tooling cost.

At Stern Industries, we manage and outsource all of our injection molding, whether volume is low or high. The processes we provide includes thermoplastic molding, insert molding, thermoset molding, and two-shot molding. When installing injection moldings, we carefully monitor pressure and temperature to ensure long-term elasticity, durability and strength. Check out the following page of our website for more information about our injection molding services.


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