Make · process

Blow moulding

A soft tube inflated against a mould

Hollow parts — above all bottles — made by inflating a hot tube of polymer (a parison) against the walls of a mould with air. It is the cheapest way to make a light, hollow, thin-walled container in the billions.

Very high
Volume
Moderate–high
Tooling
Seconds
Cycle
Moderate
Tolerance
How it works
  1. 1
    Form a parison by extrusion or injection.
  2. 2
    Clamp the mould around it.
  3. 3
    Inflate with air so it takes the mould's shape.
  4. 4
    Cool and eject the hollow part.
Strengths & limits
Strengths
  • Very cheap hollow parts at huge volume
  • Thin walls, light weight
  • Complex bottle shapes, necks and handles
Limits
  • Hollow parts only
  • Wall-thickness control is tricky
  • Lower tolerances than injection moulding
Typical parts & materials

Typical parts: Bottles, containers, fuel tanks, ducts, drums

Commonly run in — open one for its cited properties:

HDPEPETPPPVC

Part of the Make map of manufacturing processes. Browse the cited database, or see where these parts end up in the application domains.