Blow molding is a type of plastic forming process for creating hollow plastic products made from thermoplastic materials. The process involves heating and inflating a plastic tube known as a parison or preform.
Plastic blow molding originated from the ancient process of glass blowing. Both glass and plastic in their molten state can be formed easily by introducing small amounts of air inside the molten material.
Blow molding is a fairly straightforward process that includes melting, homogenizing, extruding, molding (blowing), cooling, and ejection.
There are two main types of blow molding: extrusion and injection blow molding. They differ according to the method of producing the preform or parison.