Blowmolded

Blowmolded describes products manufactured by blow molding, a plastic forming process used to create hollow, thin-walled parts by inflating a heated polymer against the walls of a mold. The term can refer to the process or to items produced by it, such as bottles and containers.

Blow molding encompasses several methods, including extrusion blow molding, injection blow molding, and stretch blow molding. In extrusion blow molding, a parison (a heated plastic tube) is extruded between two mold halves and then expanded with compressed air to take the mold's shape. In injection blow molding, a preformed plastic part is injection molded first, then transferred to a blow mold where air expands it to the final contour. Stretch blow molding combines preforming with stretching during inflation, typically used for high-volume PET bottles.

Process steps include heating the polymer, forming a parison or preform, closing the mold, inflating the parison with air to press it against the mold surfaces, cooling, and ejecting the finished part.

Materials used in blow molding include common polymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), and polyvinyl chloride (PVC).

Applications are wide-ranging, with blowmolded parts used for consumer packaging like beverage bottles and detergent containers, as well as industrial drums, medical containers, and automotive fuel tanks.

Advantages and limitations: blow molding enables lightweight parts with relatively thin walls and relatively low tooling costs for high-volume production, but it can produce uneven wall thickness and has design constraints regarding undercuts and complex internal features. Tooling costs can be high, and recycling depends on material and local recycling infrastructure.

Blowmolded parts are typically recyclable where facilities exist, and the process remains common in plastic fabrication for mass-produced hollow items.