Blow molding is a method of injection molding hollow molded items such as PET (polyethylene terephthalate) bottles for juice, etc.
This method is being used widely in the world for manufacturing shampoo containers, containers for spices such as soy sauce, or containers for detergents, etc.
The plastic resin that can be blow molded are polyethylene terephthalate, polypropylene, polyvinyl chloride, nylon, polycarbonate, etc.

Blow molding is done using a special blow molding machine. And also, the mold used has only a female type cavity and there is no male type core.
Instead of that, there is a nozzle for blowing air into the mold, a pre-formed balloon shaped molded item called a parison is blown and made to contact the cavity closely thereby transferring the shape.

In the case of blow molding, usually a relatively soft metal is used for the cavity. While aluminum alloys, bronze, etc. are commonly used, special steels are also used.
Since very frequently beautiful glossiness is expected in the surface of the molded item, sufficient care has to be taken about polishing the inside surface of the cavity.

Further, multiple cavities in a mold are common in the blow molding of containers for drinks, and since a high cycle rate is expected, techniques will be necessary for the function of cooling and adjusting the temperature of the mold.

Since most of the blow molded items are of the disposable variety, it is extremely important that the product design and planning and the mold design are made considering the recycling of these products.