Generally, it involves heating as well as injecting the plastic material under pressure in a closed metal mould tool. Furthermore, the molten plastic cools & hardens into the shape inside the mould tool. This opens to allow the mouldings to eject or remove for inspection and delivery

Actually, plastic injection molds are typically constructed from hardened or pre-hardened steel, aluminum, and/or beryllium-copper alloy. Although, steel molds cost more, plastic is more durable.

Undoubtedly, the main factors for high cost are the size and intricacy, material used, and number of parts we produce.

3D Printing appears expensive than injection molding.However, the 3D printing cost per part is only $0.70 per part, and there is no initial investment for set-up.

Steps-

Design the Mold in CAD. 

3D Print the Mold.

Molding the Plastic Parts.

Generally, we use Injection molding to create high volumes of things such as wire spools, packaging, bottle caps, automotive parts and components, toys, pocket combs, one-piece chairs and small tables, storage containers, mechanical parts (including gears) etc.

6 Types-

Thin Wall Molding.

Gas-assisted Injection Molding.

Metal Injection Molding.

Liquid Silicone Injection Molding.

3D Printing.

Unique Material Formulations.

In 1868, in response to a request by billiard ball maker Phelan and Collander, John Wesley Hyatt invented a way to make billiard balls by injecting celluloid into a mould. By 1872, John and his brother Isaiah Hyatt patented the injection moulding machine.

For this PTT melt and mold temperatures were suggested to be between 232–260°C and 88–121°C, respectively

3D printing the injection molds is a cost effective way for low-run injection molding. Material Jetting and SLA are preferable for 3D printing injection molds. Thus, we use each 3D printed mold for approximately 30 – 100 runs.