Pet Preform Injection Molding Colour Change with EasyPurge Purging Compound

OPAQUE White to Clear

Goal: Color Change and Scrap reduction


Machine: Husky 

Extruder Diameter: 110 mm

Material: PET

Colour: Opaque White to Natural

Mould: 72 x 22 grs

Factory Location: Mexico


24 hours later we confirmed there was no presence of White PET contamination during the next two shifts.

The machines parameters were adjusted due to an increase of the MFI.

Normal Results using Pellet Purging Compound 

Time: 3:30 HoursScrap: 600 KgsPurging Compound consumed: 43 Kgs

Using EasyPurge Purging Compound

Time: 1:30 Minutes Scrap: 150 KgsPurging Compound used: 760mlVirgin Material Consumed: 76 Kgs

1. Original Prefrom Colour: Opaque White.

2. Once the barrel and the piston were cleaned with Easypurge purging compound, virgin PET started to be injected into the mould. Easy purge was dosed into the mixer using Easypurge Automatic Purging System (APS).

3. Easypurge emulsifies colour pigments injecting preforms in automatic.

4. The Easypurge Automatic Purging System stopped adding purging compound. The process was finished using virgin PET to remove the rest of impurities and colour pigments emulsified by Easypurge.
5. Finally, the dosing of Easypurge was stopped, using virgin material to remove the rest of the purging compound leaving the hot runners clear of colour contamination.

Final Results:


Purging Compound used


Colour Time Change

Pellet Purging compound

43 Kgs

600 Kgs

3:30 Hrs


760 Ml

226 Kgs

1:30 Min

Comment by the Process manager:

“We used the APS to change color from opaque to clear. It is easier to use than any other method we have used before. We managed to clean the screw and the hot runners also and the result is very positive. We are happy to see that we produced less than 50% scrap than before”.

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