The New Moneymaker: Injection: Blow Moulding Process

Injection Blow Molding (IBM) is one of several blow methods used to make plastic products. Others are extrusion blow moulding, spin trimming and spin stretch.

The main characteristic that separates injection blow moulding from other blow processes is the use of pressure to literally inject the polymer that is being moulded into a core pin where it is inflated then left to cool. IBM is the most common moulding process used to make small hollow plastic containers like medicine bottles on a large scale.

The process can also be used to mould glass although glass containers are generally less popular in daily use. Due to its suitability for only small containers, IBM is the least popular of blow moulding processes. Yet it remains an important production process because of the high quality of its end products.

IBM is done in three stages:

  • Injection – The stage where the polymer (raw material) is melted and pressurized (injected) into the mould whose shape it is intended to take.


  • Blowing – The second stage which involves cooling of the moulded container while it is still bound to the pre-formed mould. The polymer is inflated into the final container shape.


  • Ejection- This finalization stage involves removal of the supporting mould to leave a finished product.

Will other methods replace injection blow moulding?

Probably not. It would be accurate to make that assumption if other moulding processes had overtaken IBM in the first place. However, this model has had little popularity for a long time mainly due to its ineffectiveness in the production of large containers.

However, the little IBM-moulded bottles are of great quality and cost-effective when produced in large numbers. These two factors make Injection Blow Moulding a process likely to remain in use for the long term. The invention of new core pins also ensures it keeps re-inventing itself.

IBM is like that little corner shop that you never do major shopping from but wouldn’t imagine living without.

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