Injection molding is a manufacturing process for producing parts by injecting molten material into a mold or mold. Injection molding can be performed with a host of materials, including metals (for which the process is called die-casting), glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed (using a helical screw), and injected into a mold cavity, where it cools and hardens to the configuration of the cavity.[1]: 240  After a product is designed, usually by an industrial designer or an engineer, molds are made by a mold-maker (or toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part. Injection molding is widely used for manufacturing various parts, from minor components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection molding of some lower-temperature thermoplastics, can be used for some simple injection molds.

Injection molding uses a special-purpose machine with three parts: the injection unit, the mold and the clamp. Parts to be injection-molded must be very carefully designed to facilitate the molding process; the material used for the part, the desired shape and features of the part, the material of the mold, and the properties of the molding machine must all be taken into account. The versatility of injection molding is facilitated by this breadth of design considerations and possibilities.

The Injection molding process is used to produce parts shaped via injecting material into a mold. It can be done with different materials but is most often done with thermoplastic and thermosetting polymers. A material to manufacture a part will be fed into a heated barrel, mixed, and then forced into a mold where it cools and hardens to the shape of the cavity.

Injection molding is used to create a variety of parts, from small pieces to car body panels. 3D printing technology is also starting to be used since photopolymers can be used in simple injection molds.

Parts that are to be molded have to be designed very carefully to make the molding process possible. Particular attention must be paid to the material used for the part, the shape and features of the part, the material of the mold, and the properties of the molding machine.

Many things are created using injection molding. Wire spools, packaging, bottle caps, automotive parts and components are some things manufactured using the process. It is the most common method to manufacture plastic parts as high volumes of the same object can be made.

Injection molding has benefits like a wide range of materials that can be used, and the labor costs remain low. Not a lot of scrap material is produced during the manufacture of parts, and there is usually no need to do any finishing work on the parts.

Injection molding start-up can be expensive because of the high cost of equipment and the running costs. Molds may cost a fair amount as well. But once a business is established, the costs, later on, remain low.