Blow molding

Blow molding

Gestión de Compras have the means to produce components by blow molding with a high versatility.

Process of blow molding

Blow molding, also called as plastic blowing, is a molding process in which air pressure is used to inflate soft plastic into a mold cavity. It is an important industrial process for making one-piece hollow plastic parts with thin walls, such as bottles and similar containers.

Blow molding is accomplished in two steps: first, fabrication of a starting tube of molten plastic, called parison and second, inflation of the tube to the desired final shape.

There are several forms of blow molding:

1 Extrusion Blow Molding (EBM)

Plastic is melted and extruded into a hollow tube (a parison). This parison is captured by closing it into a cooled metal mold. Air is then blown into the parison, inflating it into the shape of the hollow bottle, container, or part. After the plastic has cooled sufficiently, the mold is opened and the part is ejected.

2 Injection Blow Molding:

It is a process combining injection molding and blow molding. The molten plastic is injection molded around a core inside a parison mold to form the hollow parison. When the parison mold opens, both the parison and core are transferred to the blow mold and securely clamped. The core then opens and allows pressurized air to inflate the parison.

3 Stretch Blow Molding

For multiwall or multilayer pieces. It is a two stage process similar to that of injection blow molding. First the preforms are made using injection molding or a similar process. The preforms are then heated up, usually with infrared heaters. Then it is blown with high pressure air using metal blow molds while the preform is stretched using a core rod. Compressed air continues to blow in until the preform reaches the wall of the mold.


For the realization of the mold, Gestión de Compras adapts to the needs and the guidelines set by each customer. In this way, the customer gets the exact mold you need to prepare your products.

Materials and products

The materials are chosen for their physical properties, cost and environmental utilization. And are as follows the most used:

  • Polyethylene (PET): It is the most common for making bottles.
  • Low density Polyethylene (LDPE, LLDPE).
  • High density Polyethylene (HDPE).
  • Polypropylene (PP).
  • Polyvinyl chloride (PVC).

The products manufactured by blow moulding are widely used in many industrial fields and everyday lives such as automobile, consumer, electronics, fuel oil tanks, furniture, health safety, packaging, tool cases, toys…



In blow molding dimensional tolerance depends heavily on the part size and wall thickness. Parts should be dimensioned according to the outside form. The wall thicknesses can vary widely based on many factors.

Standard and certificates


We have the means to ensure our products comply the general regulation and the specific certificated regulations in manufacturing products that requires them.

  • ISO 9001 e ISO 14001
  • TS 16949
  • ISO 8062, ISO 286-2, DIN 2768, DIN 1697, etc.
  • OHSAS 18001
  • ISO 13106