Blow molding

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The blow molding is a process for producing hollow bodies from thermoplastic plastics and one of the injection molding processes .

Procedure in blow molding

Procedure in blow molding

For blow molding, what is known as a preform is required, which is produced in a previous work step by conventional injection molding. In the actual blow molding process, this preform is heated in the first process step. Infrared emitters are mainly used here, as they are not only easy to automate, but also have high performance and bring a lot of thermal energy into the semi-finished product. After heating, the preform is moved into the tool; alternatively, depending on the type of machine, the heaters are moved out of the tool. Closing the tool results in longitudinal stretching on the bottle neck, which holds the preform axially and also creates a media-tight fixation. A gas is then introduced into the preform, which expands under the pressure load and reproduces the mold contour. Compressed air is often used as the gas for economic and ecological reasons. After inflation, the hollow body produced cools down in the tool until it has sufficient dimensional stability and can be ejected.

A preform is heated and inflated in a shaping blow molding tool so that it rests against the contour of the tool. Depending on the manufacture of the preform, a distinction is made between extrusion blow molding and stretch blow molding .

Range of parts

Hollow plastic components can be produced by means of blow molding. These are referred to as plastic blow molded parts or blow molded parts. Plastic bottles, plastic canisters, washing water tanks, fuel tanks, expansion tanks or similar components can be named as examples. One advantage of hollow body blow molding is the thin wall thickness of the manufactured parts, in contrast to alternative processes.

Individual evidence

  1. ↑ Günter Mennig: Tool making in plastics processing: types, production, operation , Hanser Verlag, 2008, ISBN 3-446-18257-8 , page 133ff ( online preview on GoogleBooks).
  2. ↑ Article " Blasformen " on www.kunststoffe.de (Hanser Verlag).
  3. ↑ Molded parts, injection molded parts, blow molded parts, rotational parts. Retrieved January 8, 2019 (German).

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