Liquid injection molding is the process of melting materials into a liquid, injecting the liquid into a mold, and letting the liquid cool into a hardened shape. The process is commonly used to make parts for all sorts of industries, from food products to electronics. Plastic, rubber, or metal can be used for injection molding, but only plastic and rubber are considered to be liquid injection molding materials.

Liquid Injection Molding Properties

Heat is the primary factor in liquid injection molding. Rubber and plastic pellets can be melted into liquid when they are exposed to high temperatures. A different process is used for metal injection molding. Metal powder is combined with a small amount of binder initially. This powder is then injected carefully into the desired mold. The metal powder will shrink and surface pores will minimize as the mold is exposed to extremely high temperatures. This is different from liquid injection molding because heating is the primary method for hardening parts as opposed to cooling.

Silicone rubber is the easiest type of rubber to work with for liquid injection molding. It flows very easily and can be molded using fairly low amounts of energy. Silicone rubber is typically transparent, unlike organic rubbers. It is also desirable because it has no taste or smell and it is suitable for food contact.

Plastic is the most commonly used material for liquid injection molding. Plastic is desirable because it is durable, lightweight, easy to work with, and also comparatively low in cost. Clear plastics such as acrylic, nylon, polycarbonate, ABS, PVC, polyester, polyurethane, and polystyrene are commonly used to create parts. To effectively remove parts from molds while avoiding stress to the design, plastic molds should be designed with angles, uniform walls, and rounded corners.