What is stretch blow molding process?

Nowadays, the Blow Molding Machinery Manufacturing industry has a moderate level of capital intensity. In addition to acquiring, maintaining and updating specialized technical equipment, companies must have access to competitively priced raw materials. Once

Linear stretch blow molding machine for drinking bottles DMK-L8

more, the manufacturers require a skilled workforce. Customer specifications for blow molding machines have high degrees of functional expertise embedded in them. Thus, operators must be able to attract skilled labor, especially technical engineers, which represents a significant cost. SoDemark Machinery train the research and development teams to develop new technologies to remain competitive. Now, Tina will tell you the process of stretch blow molding.

First, the plastic is molded into a “preform” using the injection molding process. These preforms are produced with the necks of the bottles, including threads on one end. These preforms must be packaged, and fed later (after cooling) into a reheat stretch blow molding machine. In the SBM process, the preforms will be heated (typically using infrared heaters) above their glass transition temperature, then blown using high pressure air into bottles using metal blow molds. The preform is always stretched with a core rod as part of the process. In the single-stage process both preform manufacture and bottle blowing are performed in the same machine. The stretching of some polymers, such as PET (polyethylene terephthalate) results in strain hardening of the resin, allowing the bottles to resist deforming under the pressures formed by carbonated beverages.The main applications are bottles, jars and other plastic containers.

The engineer of Demark Machinery said several advantages of blow molding: fast production rates, low tool and die cost, ability to mold complex part, produces recyclable parts. And the disadvantages is: wall thickness is hard to control and limited to hollow parts.

Demark Machinery in China, more than years experience in blow molding machine, provide engineering/consulting services, machines and PET preform moulds. email tina@demark-pet.com, I’m TINA, best regards.