Blow Molding Process Comparison

April 7, 2010
|In Blow Molding, Injection Molding
|By admin

If you are new to blow molding or if you have been in the industry for 30 years, it can still be confusing as to what type of blow molding machinery or process is best for your next application. I have been fortunate in my career to design and build machinery for every type of blow molding process. For your information I consider there to be 7 primary machinery processes for packaging applications.

  1. Shuttles (Continuous extrusion)
  2. Wheels (Continuous extrusion)
  3. Injection Blow
  4. Injection Stretch Blow (1 Step)
  5. Reheat Stretch Blow (2 Step)
  6. Reciprocating screw (Intermittent extrusion)
  7. Accumulator Head (Intermittent extrusion)

Some people may refer to them differently and some may argue several of these should be grouped together, but for sake of discussion, we will use this grouping. Further definition of the technologies, along with pros and cons for each process, can be found in the links above.

Shuttle Wheel Injection Blow Injection Stretch (1-Step) Reheat Stretch (2-Step) Recip Screw Accumulater HD
HDPE Yes Yes Yes No No Yes Yes
PP Yes Yes Yes Sometimes No Yes Yes
PET No No Yes Yes Yes No No
PVC Yes Yes Yes No No No No
Styrene No No Yes No No No No
Multilayer / coinjection Yes Yes Difficult Difficult Difficult No Difficult
IML Yes Yes No No No Difficult Difficult
Handleware Yes Yes No No No Yes Yes
Injection Finish Good Fair Excellent Excellent Excellent Fair Good
In-machine Deflashing Yes No N/A N/A N/A No No
Flashless Process No No Yes Yes Yes No No
Small Bottle<100 ml

low/med vol.

 Yes No Yes No No No No
Small Bottle<100 ml

high vol.

 Yes Maybe Yes No No No No
Med. Bottle(1 litre)

low vol.

 Yes No Yes Yes No Yes No
Med. Bottle(1 litre)

high vol.

 Yes Yes No No Yes Yes No
Large Bottle(4 litre)

low vol.

 Yes Yes No No No Yes No
Large Bottle(4 litre)

low vol.

 No Yes No No No Yes No