Extrusion Blow Moulding: Definition and Process

What Is Extrusion Blow Moulding?

Extrusion blow moulding is a manufacturing process used to produce plastic bottles and containers. Plastic resin is melted and extruded into a hollow tube, which is then clamped between two halves of a water-cooled mould.

Pressurised air is introduced into the tube, forcing the heated plastic against the inside of the mould cavity. The plastic cools and takes the shape of the mould. The mould then opens and releases the finished bottle.

Advantages of Extrusion Blow Moulding

One important advantage of extrusion blow moulding is the flexibility to change the neck configuration without replacing the entire bottle mould. This allows different neck fitments to be used with the same bottle mould and can reduce tooling costs.

The process can produce bottles with a wide range of:

• Shapes and sizes
• Neck types
• Plastic materials
• Complex contours and designs

Materials Used in Extrusion Blow Moulding

HDPE (high-density polyethylene) is one of the most commonly used materials for blow-moulded bottles. Although naturally opaque, HDPE can be manufactured with a high-gloss appearance.

MDPE (medium-density polyethylene) can be used when a more flexible or squeezable bottle is required, for example for creams and lotions.

Key Advantages

Extrusion blow moulding can provide:

• Good resistance to alcohols, acids and alkalis
• High bottle stiffness
• Interchangeable neck moulds
• Good recyclability
• The ability to produce complex shapes and sharp contours

The process is therefore widely applicable to cosmetic packaging where flexibility in bottle design and neck configuration is important.