Plastic injection molding is a manufacturing process that usually creates parts from plastic, metal and other materials by injecting material into a mold cavity.
There are two main types of plastic injection molding: co-injection and single-shot plastic injection. Co-injection uses two tools to inject molten material simultaneously, and in contrast, single shot injection only utilizes one tool to inject the molten material.

Plastic injection molding is a process which forms a plastic part by injecting molten polymer into a mold.
The plastics industry is one of the fastest developing sectors in the material world. There are different types of plastic, but by far the most popular ones are thermoset resins (such as epoxy and polyester) and thermoplastic resins (such as polyurethane and ABS).
Some of these plastics have properties that make them particularly well-suited for injection molding.
Injection molding has been known to produce very accurate parts with high repeatability, even using recycled plastics.

Injection molding is a process of manufacturing plastic products. Plastic pellets are heated and fed into an injection machine. Inside the injection machine, the molten plastic is injected into a mold cavity, which has been cooled and prepared to shape the raw material into its new shape. The machine then opens up for removal of the finished product.
The advantages of this method are that it does not require expensive tooling and can produce high volumes of product quickly for low unit prices.
When you need to produce high volumes of a product that does not need much changes, injection molding is your go-to process.