PLASTIC BLOW MOLDING

PLASTIC BLOW MOLDING (also known as blow moulding or blow forming) is a manufacturing process by which hollow plastic parts are formed. In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and stretch blow molding. The blow molding process begins with melting down the plastic and forming it into a parison or preform. The parison is a tube-like piece of plastic with a hole in one end in which compressed air can pass through.

The parison is then clamped into a mold and air is pumped into it. The air pressure then pushes the plastic out to match the mold. PET preforms manufacturers in india Once the plastic has cooled and hardened the mold opens up and the part is ejected.

blow molding has been recently demonstrated under pressures and temperatures comparable to PLASTIC BLOW MOLDING. This technique allows molding BMGs with an about 50 times higher strength than plastics into shapes that were previously not achievable with crystalline metals.

PLASTIC BLOW MOLDING

STRETCH BLOW MOLDING

In the STRETCH BLOW MOLDING process, the plastic is first 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 are packaged, and fed later (after cooling) into a reheat stretch blow molding machine. In the SBM process, the preforms are heated above their glass transition temperature, then blown using high pressure air into bottles using metal blow molds. Usually the preform is 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 preforms manufacturers in india results in strain hardening of the resin, allowing the bottles to resist deforming under the pressures formed by carbonated beverages, which typically approach 60 psi.PET preforms manufacturers main applications are bottles, jars and other containers.

Advantages of blow molding include: low tool and die cost; fast production rates; ability to mold complex part; produces recyclable parts.

STRETCH BLOW MOLDING