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
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
Black, Kohser, Materials and Processes in Manufacturing.