Blow moulding process is a primary method used in the plastics industry to manufacture hollow plastic items such as bottles, containers, and industrial parts. This process allows for efficient production of products with varying wall thicknesses and complex shapes using materials like HDPE, PP, and PVC

Key Stages of the Blow Moulding Process

Material Preparation and Parison Extrusion:

• Material Feeding: Plastic pellets (e.g., HDPE, PP, PVC) are loaded into the extruder’s hopper.
• Melting & Conveying: Inside a heated barrel, a rotating screw melts and homogenizes the plastic material through a combination of external heaters and frictional shear, ensuring a consistent melt temperature and
  viscosity.
• Parison Formation: The molten plastic is continuously pushed through a die head which precisely shapes it into a hollow, molten plastic tube (the parison) that hangs vertically from the die.

Parison Clamping and Inflation:

• Mold Closing: As the parison reaches a predetermined length, a two-part mold closes rapidly around it. This action pinches one end of the parison closed
• Inflation: Compressed air is then rapidly introduced into the interior of the parison through a blow pin or needle, forcing it to expand and conform precisely to the inner shape of the cooled mould cavity.

Cooling and Finishing:

• Cooling: The hot plastic quickly cools and solidifies upon contact with the cold mould walls
• Mold Opening & Ejection: Once the product has sufficiently solidified and cooled, the mould opens, and the newly formed hollow plastic product is automatically ejected.
• Flash Trimming: Any excess plastic, known as “flash,” created at the pinch-off points is precisely trimmed off and recycled back into the production stream to minimize material waste.