注射制模 （Injection moulding）是一种生产由热塑性塑料或热固性塑料所构成的部件的过程。注射成型就是将塑料(一般为粒料)在注射成型机的料筒内加热熔化，当呈流动状态时．在柱塞或螺杆加压下，熔融塑料被压缩并向前移动，进而通过料筒前端的喷嘴以很快速度注入温度较低的闭合模具内，经过一定时间冷却定型后，开启模具即得制品。这种成型方法是一种间歇操作过程。它包括两个主要部分，一个注射设备和夹紧设备。注塑机中的模具可以固定在水平或垂直位置。大多数机器是水平方向的，但垂直机器用于一些特殊应用，此过程类似铸造，材料被注入到一个被加热的桶，混合(由固态熔化成粘稠的液态)后被挤进铸模。材料可以在铸模(型腔)中冷却和凝固成铸模的形状。通常是由工业设计者或者工程师完成产品设计，注塑用铸模是由铸模制造者（或工具(模具)制造者）所制造，通常是以钢或铝一类的金属制成，而所期望的部件的外形特征由精密机械加工而成的型腔来形成。注射制模广泛用于制造各种零部件(绝大部分的塑料制品)，从汽车的最小的部分到汽车的车身皮肤。

Injection moulding is a manufacturing process for producing parts by injecting material into a mould. Injection moulding can be performed with a host of materials, including metals, (for which the process is called diecasting), glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and forced into a mould cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mouldmaker (or toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers which do not melt during the injection moulding of some lower temperature thermoplastics, can be used for some simple injection moulds.