In comparison with Injection Molding, Extrusion Blow Molding is the perfect process to create high-strength, lightweight, multi-functional products or parts made to exacting tolerances. Extrusion Blow Molding does not require the very expensive tooling investment of Injection Molds nor the huge production quantities to make Injection Molding economically feasible.
Also, Blow Molding Molds can be tooled much quicker than Injection Molds. Typically, eight to ten weeks faster than comparable size Injection Molds.
Extrusion Blow Molding creates seamless "Double Wall Construction" in one molding step. Other plastics forming operations must rely on the costly procedure of laminating two separate parts together to form "Double Wall Construction."
With Extrusion Blow Molding, a different design or pattern can be molded on the two walls in one operation. For instance, in a mold to create the base or lid of a Carrying Case, the exterior wall can be your own personal styling. The other wall would be the inside of the case. It can be molded to conform to the shape and size of the parts to be placed in the Plastic Case to securely nest and protect them from damage.
Blow Molding Production
1. A combination of high-density polyethylene plastic, resins, stabilizers and a color agent, if required, is heated to the melting point.
2. The molten mixture is forced continuously through a die head to create a tubular-shaped form called a parison. It looks like a long inflated balloon.
3. A two-piece mold closes around the parison. each side of the mold can have a different design or pattern.
4. A needle is used to force air inside the parison to inflate it.
5. The air pressure makes the molten mixture assume the shape of the two sides of the mold creating the 'Double Wall Construction.' Water circulating inside the walls of the mold cools the parison so it hardens in the desired shape.