It is the leading plastic manufacturingprocess because of wide range of plastic resin that can be blow molded. The most famous method for the production ofhollow parts out of parts vary in sizes, from very small to very large parts.The common example of blow molding is plastic bottles but other object forinstance automotive components, medical equipment and toys etc.
PRODUCTION OF THERMOPLASTIC RESIN:Blow moldingproducts are formed from thermoplastic resin. Names are mentioned below. 1.
High density polyethylene2. Medium and low density polyethylene3. Polyethylene terephthalate4.
Polypropylene5. Polyvinyl chloride6. Thermoplastic Elastomers7. Polystyrene8. Polycarbonate9. Fluoropolymers10. Polyimide TYPESOF BLOW MOLDING:It is basically classified into threemain types that are extrusion blowmolding, injection blow molding and injection stretch blow molding, each ofthree shares four common points of manufacturing.
1. Melting of resin.2. Formation of preform.3. Preform inflation and cooling in blowmolding4.
Ejection from the blow mold.EXTRUSIONBLOW MOLDING:Extrusion blow molding is further oftwo types, continuous or intermittent. In former the preform is subjected intomold and each form will be cut off as the formation is done, while in laterblow molding process, it ejects each new plastic from the metal mold when it iscooled and parison is fed into mold only after the preceding parison isexpelled out.INJECTIONBLOW MOLDING: Hopper is attached above the chamber, fromwhich plastic is filled into the rod placed inside the chamber where pressureis applied, two heaters are attached as well for the melting of plastic thenall that melted plastic is transfer into die cavity through nozzle. It is cheaperthan extrusion blow molding.INJECTIONSTRECH BLOW MOLDING:It is the combination of first twotypes. The plastic is molded first to create bottle neck, as the temperatureget decrease it is dump into stretch blow molding machine, here it is reheatedand then it is forced into a plastic bottle.
ADVANTAGESOF BLOW MOLDING:v It brings variation in the product.v It is economical.v It has are many alternative methods ofmanufacturing.v High production rate. DISADVANTAGEOF BLOW MOLDING:v It has bad effects on environment.v It is largely based on petro chemicals.v It has less uses.v It requires process and material precisionthat creates waste.