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Variations

Injection Blow Molding

Blow molding is a mean of forming hollow thermoplastic objects. A small hollow and heated plastic piece, called a parison is expanded like a balloon as air pressure is applied inside it. This will force it against the walls of a mold cavity, whose shape it assumes. There it cools and hardens. The mold opens, and the part is ejected.

In injection blow molding, the parison is made by injection molding. It is molded over a mandrel to provide the hollow shape. This mandrel transfers the hot parison to the blow-molding die where it functions as the blow nozzle.

The most common applications are containers for liquids and other items used in the household such as watering cans and bottles for laundry detergent and bleach, cooking oil, shampoo, and various cosmetics and medicines.

Another wide application area for blow molding is in the toy industry, ranging from simple balls and lightweight baseball bats to elaborate dolls and animal toys.

Source: Bralla, Design for manufacturability Handbook

Reaction Injection Molding

In reaction injection molding (RIM), two monomers are mixed together as they are injected into a mold. The two components undergo a chemical reaction to form a plastic polymer. The reaction need not be endothermic, i.e., does not require heating. Rather, an exothermic reaction occurs where the heat generated must be removed. Production rates are determined by the curing time of the polymer, which is often less than one minute.

Source: DeGarmo, Black, Kohser, Materials and Processes in Manufacturing.