Blow mold is used for the manufacture of thermoplastic hollow bodies. This method is one of the unique methods of injection molding. Blow molding (or molding) is a manufacturing process for forming and joining together hollow plastic parts. It is also used for forming glass bottles or other hollow shapes. Next, we are going to show you everything you need to know about blow molding.

During the production phase, a pre-extruded or injection molded preform is created using internal pressure on the contour of the blow mold. In addition, these can be easily manufactured to packaging products such as containers, bottles or barrels, and several other technological components. This involves shells and semi-shells, as well as fuel tanks and ventilation ducts of different cross-sections. There is a distinction between the extrusion blow molding and stretch blow molding depending on the produce of the preform.

The phase of blow molding
There are variations in all ways of blowing Molding of the extrusion blast and stretching bladder. The so-called preform is a requirement for two blow molding styles. The preform may be continuously created by extrusion or by injection molding separately according to the method used. The preform is normally created by extrusion blow molding for stretch blow molding processes.

The preform is then placed in the mold where compressed air is used to grow. The workpiece gets its final geometry in the cavity throughout the expansion phase. The principle of compressed air filling is that the preform is too elastic. This can be guaranteed by a heating element (such as an infraround radiator) or direct deformation during extrusion after the plastic remains deformable enough.

Method of extrusion blast molding
Today, the hollow bodies of thermoplastics are primarily manufactured by extrusion blow molding. Two processes can be carried out in parallel during the production process using the extrusion blow molding process. On the one side, the continuous extrusion of the preform (so-called one phase formation) and, on the other, the periodical transition of the preform into the instrument by blowing air.

Process of extended blow molding
The extended blow molding is a special blow molding form. Similar to film, this approach has the following effects: in the process of painting, high orientation may be incorporated close the melting temperature of glass or crystal. This contributes to a considerable change in the commodity properties.

The so-called preform is a condition for blow molding. In the previous process stage, traditional injection molding or extrusion blow molding was made. The preform is first heated in the first phase of the blow molding. For this reason, infrared radiation is used. It can be well automated and consistency is necessary. This makes it perfect for taking heat into the semi-finished commodity in vast numbers.

Delete the heater from the tool after heating or transfer the preform into the tool. The preference depends on the system model. The bottleneck extends longitudinally while the method is closed. This allows the preform to be axially fixed. It will also create an imperceptible media look.

The preform is extended not only in the circumferential direction but also in the longitudinal direction in stretch blow molding, as opposed to the extrusion blow mold. This is achieved with the aid of stamps mechanically. Air blowing is simultaneously used for circumferential stretching. The method is conducted at very low temperatures and requires a heavy deformation power. Therefore, during this operation a blow pressure of 20 bar or more exists. After inflation, the hollow body is cooled in the tool. Eject only if the dimensional stability is necessary. Read related: design plastic parts with injection molds.