Plastic Blow Molding Overview Print E-mail

DaMar Plastics, Inc. innovative source for your blow molding needs.We are a custom blow molder and service the automotive, household, chemical, cosmetic/personal care and water industries.  Plastic containers are available in a variety of material and sizes.  We offer a wide variety of stock molds and tooling that includes wide mouth jars, canisters and plastic industrial rounds.The production of polyethylene terephthalate (PET) led to the viability of reheat stretch blow molding. The strain hardening properties of PET allowed the high volume production of plastic bottles able to resist the carbonation pressure in soft drink applications. The high clarity and economics of PET stretch blow molding have made this a popular production method for bottles for water, detergents, and other products.


DaMar Plastics vast knowledge of blow molded parts leads us to produce quality products.  We remove limitations to give our customers fast results and better quality than our competitors.  We use the latest technology in bottles and offer in house services to help create your own custom bottle to meet your specific needs.  We have the ability to design custom molds and tooling for new retail or industrial product launches, with the flexibility to meet your future needs.

parison plastic extrusion
Parison plastic extrusion
Injection blow molding

The process of Injection Blow Molding (IBM) is used for the production of hollow glass and plastic objects in large quantities. In the IBM process, the polymer is injection molded onto a core pin; then the core pin is rotated to a blow molding station to be inflated and cooled. This is the least-used of the three blow molding processes, and is typically used to make small medical and single serve bottles. The process is divided into three steps: injection, blowing and ejection.


The injection blow molding machine is based on an extruder barrel and screw assembly which melts the polymer. The molten polymer is fed into a manifold where it is injected through nozzles into a hollow, heated preform mold. The preform mold forms the external shape and is clamped around a mandrel (the core rod) which forms the internal shape of the preform. The preform consists of a fully formed bottle/jar neck with a thick tube of polymer attached, which will form the body.

The preform mold opens and the core rod is rotated and clamped into the hollow, chilled blow mold. The core rod opens and allows compressed air into the preform, which inflates it to the finished article shape.

plastic stretch blow molding process
Plastic Stretch Blow Molding Process
Stretch blow molding

In the Stretch Blow Molding (SBM) process, the plastic is first molded into a "preform" using the Injection Molded Process. These preforms are produced with the necks of the bottles, including threads (the "finish") on one end. These preforms are packaged, and fed later (after cooling) into an EBM blow molding machine. In the SBM process, the preforms are heated (typically using infrared heaters) above their glass transition temperature, then blown using high pressure air into plastic bottles using metal blow molds. Usually the preform is stretched with a core rod as part of the process. The stretching of some polymers, such as PET (Polyethylene terephthalate) results in strain hardening of the resin, allowing the plastic bottles to resist deforming under the pressures formed by carbonated beverages, which typically approach 60 psi.


DaMar Plastics can supply  finished quality packaged to your exact specifications and can deliver on time and on a budget. Our most popular product families are shown below.  In addition, we offer a wide selection of materials, colors, and neck finishes.

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