5 Reasons Why Purging Compounds Are the Key to Cleaner, More Efficient Molding Operations
What Are the Different Types of Purging Compounds?
Purging compounds, also called purge compounds, are specially formulated resins used to clean plastic processing machines. Designed for use in equipment like molding machines, hot runner systems, and extrusion lines, purge compounds remove residual polymers, colorants, and carbonized materials from the machine's barrel, screw, and other internal components.
There are two main types of purge compounds: mechanical and chemical.
- Mechanical purging compounds use high-viscosity materials to scrub the inside of the machine, pushing out old resins through sheer force and friction.
- Chemical purging compounds, on the other hand, include additives that chemically react to break down stuck-on residues, even in areas of low flow, like dead zones or corners of the screw.
Both methods have their place, depending on the application, equipment, and resin type being processed. So, what makes purging compounds so essential?
1. Purging Compounds Reduce Machine Downtime
Unscheduled machine downtime is one of the biggest drains on productivity in injection molding, extrusion, or blow molding. Contaminants such as carbonized residue, degraded material, and color remnants can bring your production to a halt, especially if left to accumulate in hard-to-reach areas of the screw or barrel.
You can dramatically reduce downtime by incorporating purging compounds into your cleaning routine. Whether mechanical or chemical, these compounds efficiently flush out residual materials during changeovers, allowing you to resume operations faster and with fewer complications.
2. They Improve Part Quality and Reduce Scrap
Contaminants don't just hurt productivity. They also hurt your final product. When black specks, streaks, or unwanted pigments show up in finished parts, the result is scrap, rework, or worse, rejected batches. Poor purging practices are often the hidden culprit behind inconsistent part quality.
Purge compounds eliminate these defects at the source. Chemical purging compounds can even reach areas of your molding machines that typical flushing methods miss, breaking down stubborn residues before they compromise your product. The result? Cleaner transitions, higher-quality parts, and significantly less waste.
3. They Save Time and Money in the Long Run
Some processors try to save costs by purging with virgin resin or even manually disassembling equipment for cleaning. But, these approaches are often more expensive in the long term. Virgin resin lacks the aggressive cleaning action of true purging compounds, leading to longer purge cycles and more wasted material. Manual disassembly, meanwhile, increases labor costs and introduces the risk of damaging equipment.
A strategic purging process saves both time and money by improving changeover speed, minimizing material waste, and extending the lifespan of your molding equipment. Many compounds are even formulated to work across various resins and temperatures, making them a versatile and cost-effective solution.
4. Purging Compounds Extend Equipment Life
Every thermoplastic process, especially those involving high-temperature resins, leaves behind material deposits. Over time, these residues can lead to torque issues, corrosion, or even permanent damage to screws, barrels, and other internal surfaces. By cleaning these components regularly, purging compounds helps prevent long-term wear and degradation.
Mechanical and chemical purging solutions contribute to your machinery's overall health, helping preserve performance and investment. Consider it preventive maintenance that pays dividends in reduced repair costs and improved uptime.
5. They Streamline Color and Material Changeovers
Color and material transitions are some of the most sensitive operations in the plastic molding world. Inconsistent purging between runs can result in cross-contamination, requiring lengthy cleanup procedures or rejected products.
Using purging compounds specifically designed for these changeovers makes transitions cleaner and faster. Whether switching from dark to light pigments or from one resin family to another, a well-chosen purging compound clears out the residual material without requiring multiple purge cycles or extended downtimes.
Some purge compounds are designed to be used directly through hot runner systems, making them ideal for complex, closed-loop systems where residue buildup can be tough to eliminate.
When to Use Purging Compounds
If you're already ordering plastic parts or mold release, you understand the importance of maintaining clean, contaminant-free molds for consistent, high-quality production. Switching between materials or colors isn't just common for molders who handle custom work—it's constant. And with every changeover comes the risk of contamination, downtime, and defective parts.
This is where purging compounds like RapidPurge shine.
Injection molding, blow molding, and extrusion equipment all operate under high heat and pressure, creating the perfect environment for the carbonized residue to form in the barrel screw, nozzles, or hot runner systems. Polycarbonate, in particular, is notorious for leaving behind black specks—and if you're tossing parts due to these imperfections, you're also tossing profits. That's why a thorough purging process should be standard whenever:
- You're changing materials or colors
- Starting up or shutting down molding machines
- Encountering degradation or excessive scrap
- Working with sensitive resins like polycarbonate
- Cleaning the barrel and screw between runs
Why RapidPurge Is the Ultimate Purging Compound for Demanding Molding Operations
RapidPurge is a thermoplastic chemical purging compound engineered for demanding purging applications. Its proprietary mineral package offers exceptional mechanical scrubbing, while heat-activated foaming agents clean even the hardest-to-reach dead zones. This powerful combination cuts purge times, sometimes by half, saving you time and money with every cycle.
Easy to feed and available in pellet form, RapidPurge is non-abrasive, hot runner safe, and ideal for both shutdown/start-up sequences and mid-shift transitions. Even if the residue is left in the machine, it won't burn or degrade during cool-down, making it one of the safest, most effective purging compounds on the market.
So, whether you're working with a wide range of thermoplastics or running high-volume custom orders, integrating the right purging solution ensures your molding operations remain clean, consistent, and cost-effective.
Enjoy Cleaner Runs with Help from Stoner Molding
Purging compounds are a must-have tool for any operation seeking to optimize output and minimize headaches. From reducing machine downtime and material waste to improving part quality and changeover speed, these compounds play a pivotal role in keeping your thermoplastic process running efficiently.
We understand your challenges at Stoner Molding and offer a complete line of high-performance purge compounds tailored for injection molding, blow molding, extrusion, and more. Ready to see the results for yourself? Contact us today and request a free sample and discover how much cleaner, faster, and more cost-effective your molding operations can be.