Views: 1 Author: Site Editor Publish Time: 2025-07-14 Origin: Site
If cleaning an extruder screw with a purging compound were as easy as tossing a scoop of detergent into a washing machine, life would be much simpler!
In reality, however, the effectiveness of different purging compounds varies significantly based on temperature, pressure, and soak time. Often, premium, high-efficiency purging compounds can cost more per pound than the resins they’re cleaning out—which makes budget-conscious plant managers hesitant.
This article explains how to pair the right purging compound with effective process management to minimize downtime, streamline color and resin changeovers, and ultimately improve profitability in plastic extrusion and injection molding operations.
Three Common Mistakes to Avoid When Using Purging Compounds
1. Using cheap virgin resin or regrind to purge
To save costs, some processors use cheaper virgin resin or regrind before switching to a commercial purging compound. But this old-school method actually worsens buildup. Virgin resin or regrind simply coats leftover deposits and carbon contamination inside the barrel instead of removing them, making it harder to clean effectively.
2. Choosing a purging compound based only on cost per pound
Evaluating purging compounds solely by price often overlooks hidden costs:
Downtime during cleaning
Amount of purge compound required
Scrap generated during changeover
Extra resin needed to push out the purge
Before comparing options, it’s critical to calculate your actual purging costs.
3. Ignoring the supplier’s recommended procedure
Many facilities still run without standardized purging procedures, relying on guesswork. Inconsistent processes between operators or shifts lead to unpredictable results. Always document and follow the purge compound supplier’s instructions closely, and provide regular training to reinforce best practices.
Invest in Continuous Training and Process Knowledge
When introducing a new purging compound, it’s common to see strong initial results. But over time, staff turnover and undocumented process tweaks can erode those gains.
Ongoing training and refresher courses are essential to keep purge performance consistent. Collaborate with your purge compound supplier for on-site and remote training resources, and keep documentation updated and visible at each machine.
Implement an Effective Purging Process
1. Create and document the procedure
Post detailed instructions by the machine, and audit the process regularly. If your product tolerances are tight, increase monitoring frequency.
2. Monitor key process variables
Track factors that can impact purge effectiveness and product quality:
Screw, barrel, and check ring wear
Pressure drop issues
Actual mold temperature
Water flow to tooling
Contamination buildup in water channels
Proactive monitoring and quick adjustments prevent small issues from turning into costly downtime.
How to Evaluate a Purging Compound Supplier
An effective purging process starts with choosing the right product:
Find a supplier that offers a range of purging compounds for your specific resins and equipment.
Confirm the compound is engineered for fast material and color changeovers.
Ask for detailed, step-by-step purge instructions.
Test product samples to compare cleaning power and overall performance against other options.
Summary:
By combining the right purging compound with strict process management, ongoing training, and supplier support, plastics processors can reduce downtime, extend equipment life, and increase profit margins—without relying on outdated, ineffective purging methods.
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