Types of Purging Compound

Purging Compound comes in different types and formulations. Each has its own characteristics and benefits. Most popular types are:

Mechanical Purge: Cleans by increasing the shear in the barrel with simple physical adjustments of the machine. 

Chemical Purge / Foaming Purge: Cleans using chemical reaction.

Liquid Purge: Typically surfactant.

Use a Suitable Purging Method
Mechanical Purge
Effective across a wide variety of applications.
  • Use the machine’s power to do the work - Most mechanical purging compounds rely on shear force and differences in material viscosities to clean injection molding machines and extruders.
  • Some mechanical purges also rely on material affinity – they are attracted to carbon and/or other plastic resins. They should not have affinity for metal.
  • There are no chemical reactions.
  • There is no soak time required.
Chemical Purge/Foaming Purge

Can be effective in areas of low pressure where mechanical purges are sometimes less effective.

  • A chemical reaction occurs in the barrel and/or die when the purge makes contact with the plastic or carbon in the barrel.
  • This reaction attempts to break the chemical bonds of the contaminant, aiding in removal.
  • Require soak times of 5-30 minutes.
  • Foaming agents are often added.
 
 
(+) Comparison of Purging Methods chart here
(+) Comparison of Purging Methods and their Characteristics chart here