Synonyms

Extrusion blow moulding procedure (also known as extrusion blow moulding, blow moulding, hollow container blow moulding, EBM)

Procedure

In a first step, a thermoplastic plastic (polymer) is melted. A screw conveyor then presses the material through a nozzle, which creates a preform. In the next step, the extruded preform is transferred into a blow mould and expanded to the contours of the mould using pressure. Because of the blow mould, a squeeze seam remains clearly visible at the joining point, particularly at the base and the neck section, which often requires reworking (spin trimming).

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Raw materials used

• Polyolefines, particularly Polyethylene (PE), Polypropylene (PP or PE-HD)
• Polycarbonate (PC)
• Polyamide (PA 6, PA 66)
• Polyphenylenoxide (PPO)
• Acrylnitril-Butadien-Styrol (ABS)
• Polymer blends
• Less often, Polyvinylchloride (PVC)
• Unsuitable: Polyester (PET)

Use

Hollow containers manufactured in this way are used as primary packing materials such as canisters or barrels and also as technical components such as fuel tanks or ventilation channels. [1]
Extrusion blow moulding makes it possible to manufacture hollow containers with a volume of about one millilitre (eye drop ampoules) to ten cubic metres (oil tanks).

Advantages

1. Rapid manufacturing speed
2. Hand grips are possible

Disadvantages

1. Because the quality of the opening is lower (squashing edges), extrusion blow moulding (EBM) is less suitable for contents that are have to be stored in a sealed and dry location or with which the content exerts pressure on the packing.
2. The extrusion blow moulding procedure is more personnel-intensive, since it requires more monitoring, regular fine adjustments and additional tools are also required.
3. The wall thickness control is difficult.
4. Often high levels of raw material consumption.

Variants

• Continuous extrusion, discontinuous extrusion
• Multi-layer blow moulding or co-extrusion blow moulding
• 3D extrusion blow moulding