Blow-Molding Process
A simple five-step sequence.

1. The formation of a parison involves extruding molten plastic into a tube that will be used to make the part.
2. Two mold halves are then closed around the parison.
3. Air is blown into the inside of the parison to expand the molten plastic against the mold surface.
4. The plastic is cooled while conforming to the new shape.
5. The molded part is removed, separated from excess parison material called flash, and finished. Most finishing steps can be completed in-mold but some involve secondary operations.