Blow Moulding Technology
A plain-language guide to how blow moulding machines turn plastic pellets into finished bottles - and how to pick the right technology for yours.
How Blow Moulding Works: Six Steps
Every blow moulding machine - from a small pharma bottle unit to a 20-litre drum line - follows the same core process.
Plasticising
Plastic pellets (HDPE, PP or PET) are melted inside a heated barrel by a rotating screw.
Parison Formation
The molten plastic is pushed through a die head as a hollow tube called the parison.
Mould Closing
A two-part mould closes around the parison, pinching and sealing its bottom.
Inflation
Compressed air inflates the parison like a balloon, pressing it against the mould walls.
Cooling
The plastic holds its new shape as circulating water cools the mould.
Ejection
The mould opens and the finished bottle drops out - trimming and flash removal included on modern machines.
Three Technologies, Three Jobs
The bottle decides the machine. Extrusion blow (EBM) handles HDPE and PP containers - the everyday workhorse for detergents, oils and jerrycans. Stretch blow (SBM) turns PET preforms into crystal-clear beverage bottles. Injection blow (IBM) makes small, precision bottles for pharma and cosmetics where wall thickness must be exact.
Match the technology wrong and you pay twice - in scrap rates at first, in machine replacement later. That is why we always start from the bottle, not the machine.
EBM - Extrusion Blow
HDPE, LDPE, PP containers from 50 ml to 20 L. Best for chemicals, food, lubricants.
SBM - Stretch Blow
PET bottles from 100 ml to 2 L. Best for water, juice, edible oil, CSD.
IBM - Injection Blow
Small precision bottles under 500 ml. Best for pharma, cosmetics, dropper bottles.
Not Sure?
Send us the bottle or the product - we tell you the right technology, free.
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