Injection Molding: What it is and What it does


Not every manufacturing operation is about size and scale. Consider injection molding one of the most important facets of modern manufacturing, it is also one of the simplest and most effective ways to improve your product’s overall presentation, durability, and in some cases, even its function.

What is Injection Molding?

Injection molding is a manufacturing process in which molten plastic is forced into a mold cavity. The molten plastic is then allowed to cool and harden. As the plastic cools, it shrinks as it solidifies. This shrinkage causes the mold to close and forces the finished part out of the mold.

The process of injection molding has been around since the 19th century, but today it is widely used for making many different types of products from small items like buttons to large components used in vehicles or machinery. Injection molding allows manufacturers to create complex parts with multiple cavities that would be difficult or impossible to create using other processes. It also results in high-quality parts that are sturdy and resistant to deformation over time.

How Does Injection Molding Work?

Injection Molding is a manufacturing process used to produce a wide variety of products. It is a complex process that involves many steps, but it can be broken down into five basic steps:


Pressurize the molten plastic and force it into a mold cavity. This requires high temperatures and pressure, which must be carefully controlled.


The molten plastic must remain in the mold long enough to cool and solidify before being ejected. The length of time required depends on the material and its characteristics. For example, some plastics may need only 3 seconds to cool while others may require 10 minutes or more. The holding step also allows any excess material to flow back into the barrel for recycling or disposal.


The cooling process depends on many factors such as material, shape of part and time needed for solidification. Cold water is often used for cooling, although hot air can also be used for large parts that require extra heat removal time (ejection time). A combination of both cold water and hot air can also be used depending on part size and complexity. Once cooled, ejection can begin immediately or after a short waiting period depending on part size and material.



The ejection process is often done manually, but it can also be done with a machine or automated system. Manual ejection involves placing a steel rod into a hole on the part and tapping on it with a hammer to break off any remaining material. This method is typically used for small parts such as jewelry and medallions and requires about less than 1 minutes for each piece.

Where does Injection Molding Get Used?

A huge number of consumer products are made with injection molding. Here are just a few:

  • Plastic bottles and containers
  • Cups, plates, bowls, and utensils
  • Lawn furniture and patio furniture
  • Plastic toys and games
  • Furniture parts and components (chairs, desks)
  • Garden hoses and watering wands
  • Electronics enclosures

What Benefits does Injection Molding Offer?

This manufacturing method offers several benefits over other methods of creating plastic parts, including. Low cost Injection molding machines are relatively inexpensive compared to other machines used for plastic production. They also require less maintenance than other machinery and don’t require skilled labor for operation or maintenance.

High quality Injection molded parts are generally stronger, more durable and more precise than other forms of manufactured plastics because they’re produced under high temperatures and pressures that ensure precision fitting with no gaps or leaks between parts. This makes them ideal for applications where strength or durability is important such as automotive parts or appliances while still maintaining aesthetics through precise detailing.


No matter what your personal beliefs, injection molding benefits businesses by being a quicker and more cost-effective method of casting parts. As such, many manufacturers both large and small use injection molding to produce a wide variety of different parts. In the end, if you need parts cast for your business, you’ll certainly want to learn everything you can about injection molding before deciding on an approach for producing your cast parts.