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Injection blow molding

Plastic forming process where a plastic tube is created in a first mold to be moved and then blow molded in another.

Illustration of Injection blow molding

The process

Plastic pellets [1] are supplied via a hopper into a rotating screw [2] whose spiral shape moves the pellet forward through a heated chamber [3].The pellets are heated gradually and turns into a homogeneous plastic melt as it approaches the end of the helical screw.

The molten mass is pressed into a mold [4] as the entire screw is pushed forward by an applied pressing force. After the mass has solidified the mold parts are separated and the part, in the form of a tube with a closed end, is removed.

A: The parts are assembled and heated up later in a different mold.

B: By pressurizing the workpiece from the inside with a gas as it expands and conforms to the walls of the mold giving us the final product.

Advantages and disadvantages
In comparison with alternative methods
Very suitable for small volumes, very suitable for short production runs
biaxial orientation gives strength
biaxial orientation provides improved barrier properties
No waste is created
Good surface finish
products with tight tolerances can be created, threads can be created
Only limited product size can be created
Higher utility costs
Some design limitations