Purging Compound for Blow Molding
A Brief Guide to Different Blow Molding Procedures
Your thermoplastic resin & its processing temperature are the deciding factor when it comes to choosing the right UNICLEANPLUS purging compound grade for your blow molding process.
Extrusion blow molding processes are categorized as either “extrusion blow” or “accumulator blow.”
We recommended talking to a Purging Process Expert at UNICLEANPLUS for right purging compound grade selection.
Mechanical Grade Extrusion Blow Purging Procedures:
- Increase the die temperatures about 55°F – 65°F
- Squeeze out the residual resin from the machine
- Then give the hopper & feed throat a good clean
- For general grades of UNICLEANPLUS purging compound, screens & dies may be left in place for purging. Talk to our technical team for correct mesh size & die clearance.
- In the event the system is contaminated heavily, it’s better to grid off thescreen pack in order to avoid plugging. If required, remove the die as well.
- Feed the needed quantity of UNICLEANPLUS purging compound into the hopper.
- Try to purge at low screw velocity first; raise the screw velocity to the highest safe level once the material starts to coming out from the head.
- Intermittently stop the screw and let the purging compound to rest for a few minutes. Recommence screw rotation at highest safe screw velocity.
- As soon as you find the purge free of impurities, dislocate the leftover purging compound with the subsequent processing resin, employing the same aforementioned procedure.
- Adjust the system parameters back to standard processing states.
- Swap the screen place with an uncontaminated one.
Accumulator Blow Purging Procedures:
- Increase the die temperatures about 55°F – 65°F
- Squeeze out the residual resin from the machine
- Give the hopper & feed throat a good clean
- For general grades of UNICLEANPLUS purging compound, screens & dies may be left in place for purging. Talk to our technical team for correct mesh size & die clearance.
- In the event the system is contaminated heavily, it’s better to grid off the screen pack in order to avoid plugging. If required, remove the die as well.
- Feed the needed quantity of UNICLEANPLUS purging compound into the hopper.
- Try to purge at low screw velocity first; raise the screw velocity to the highest safe level once the material starts to comeout from the head. If feasible, decrease the volume of the accumulator until the purge material from the screw seems free of impurity.
- Intermittently stop the screw and let the purging compound to rest for a few minutes. Recommence screw rotation at highest safe screw velocity.
- Raise back pressure to a minimum 80-90 percent if the machine
- Seal the accumulator head, and raisethe accumulator discharge velocity to the highest safe level.
- Purge 25% of the UNICLEANPLUS purging compound from the accumulator then fill it back to 100%.
- Purge 50% of purging compound from the accumulator then fill it back to 100%.
- Purge 75% of the purging compound then fill it back to 100%.
- Purge 100% of the UNICLEANPLUS purging compound.
- As soon as you find the purge free of impurities, dislocate the leftover purging compound with the subsequent processing resin, employing the same aforementioned procedure.
- Adjust the system parameters back to standard processing states.
- Swap the screen place with an uncontaminated one.
Injection Blow Molding Purging:
To know more about injection blow molding procedures, feel free to get in touch with one of our purging experts.
For our recommended purging procedures, visit https://www.unicleanplus.com/. Here you will find training videos, guidelines, technical documentation and more to answer your purging compound queries.
If you have decided to learn even more about UNICLEANPLUS purging compounds & services, don’t hesitate to schedule a free consultation with our purging process experts. We would be happy to answer your every question with absolute transparency.
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