Removing & Purging Your Barrel and Screw
Learn how to safely remove and replace the barrel on Noztek Pro and Touch extruders, plus essential techniques for purging polymer residue and preventing barrel jams.
What You'll Learn
- Safe barrel removal procedure for Noztek Pro and Touch
- When and why to remove the barrel for cleaning
- How to clean the screw after an extrusion run
- Understanding purging compounds (mechanical, chemical, hybrid)
- Choosing the right purging agent for your materials
- Preventing barrel jams with high-temperature polymers
- Proper reassembly and testing procedures
Required Equipment
- Noztek Pro or Noztek Touch extruder
- Appropriate Allen keys (provided with machine)
- Heat-resistant gloves
- Purging compound or polypropylene pellets
- Cleaning rod or brass brush (for manual cleaning)
- Safety glasses
Video Chapters
What Are Purging Compounds?
One of the key factors in achieving consistent extrusion quality is the use of purging compounds. These specialized materials are designed to clean the extruder's barrel, screw, and nozzle, removing degraded polymer material from previous production runs to ensure better product quality and consistency.
Purging agents are designed to clean the barrel and screw without the need to disassemble the machine, thus saving significant time and money. There are three main types of purging compounds:
Mechanical Type
Uses abrasive agents to scrub away contaminants. These physically remove debris as they pass through the barrel, acting like sandpaper for your extruder.
Budget Alternative: If you don't have a purging agent available, you can use polypropylene (PP) as a medium-temperature scrubbing material.
Chemical Type
Uses chemical reactions to break down debris attached to the barrel and screw. Particularly useful for clearing carbonized material.
Best For: Thorough purging after material or color changes, especially when switching from dark to light colors or between incompatible polymers.
Hybrid Type
Combines both mechanical and chemical action for comprehensive cleaning. Offers the benefits of both approaches in a single product.
Best For: Complete system purging, especially when dealing with stubborn residue or multiple material transitions.
When Should You Purge?
Material Changes
Always purge when switching between different polymer types (e.g., PLA to PETG, Nylon to TPU). This prevents material incompatibility and contamination.
Color Changes
Purging is essential when changing colors, especially from dark to light. Residual pigment can contaminate multiple kilograms of filament if not properly purged.
High-Temperature Material Runs
After extruding high-temperature thermoplastics (PEEK, PEI, PBI), degradation occurs quickly. These materials tend to adhere to both barrel and screw, which can cause barrel jams if not purged.
Extended Downtime
If the extruder will sit idle for more than a few days, purge it with a stable material like polypropylene to prevent degradation and make restart easier.
Quality Issues
If you notice specks, discoloration, or inconsistent extrusion, contamination from previous materials is the likely cause. Purge thoroughly to restore quality.
Critical for High-Temp Materials: When working with high-temperature polymers (PEEK, PEI, PBI), proactive purging with the correct purging agent will save significant time and effort by preventing barrel jams and degradation buildup.
Material Temperature vs. Purging Method
Determining how to clean your extruder depends on whether you're using high-temperature thermoplastics or lower-temperature polymers.
| Material Type | Processing Temp | Recommended Purging Method | Why |
|---|---|---|---|
| PLA, PLA+ | 180–220°C | Mechanical or PP purge | Low degradation risk, physical cleaning sufficient |
| PETG, ABS | 230–260°C | Mechanical purge | Moderate temps, occasional carbonization |
| Nylon, PC | 260–290°C | Hybrid purge | Higher temps increase degradation, needs chemical action |
| PEEK, PEI, PBI | 350–420°C | Chemical or Hybrid purge (essential) | Rapid degradation, strong adhesion to barrel/screw — jams likely without proper purging |
| TPU, TPE | 210–240°C | Mechanical purge | Flexible materials can leave residue, mechanical cleaning effective |
Recommended Purging Compound Suppliers
Here are reputable manufacturers of purging compounds with specific products designed for extrusion equipment:
Asaclean
Industry-leading purging compounds with mechanical, chemical, and hybrid options. Excellent resource for selecting the right compound for your application.
Visit Asaclean →Dugdale
Specialist purge compounds for PVC and general-purpose polymers. Wide range of formulations for different processing temperatures and materials.
Visit Dugdale →Chem-Trend – Ultra Purge
Ultra Purge line offers high-performance purging for demanding applications. Effective for both color and material changes in extrusion processes.
Visit Chem-Trend →Dyna-Purge
Comprehensive purging solutions with detailed procedural guides for extrusion startup, shutdown, and material changeovers.
Visit Dyna-Purge →Tip: When contacting these suppliers, specify your extruder model (Noztek Pro, Touch, Nexus, or Xcalibur), the materials you're processing, and your typical operating temperatures. This helps them recommend the most effective purging compound for your specific application.
Safety Precautions
- •High temperatures: Barrel and screw remain extremely hot after shutdown. Always wear heat-resistant gloves and wait for safe handling temperature.
- •Power off: Disconnect power before removing any components. Never work on energized equipment.
- •Ventilation: Some purging compounds release fumes when heated. Ensure adequate ventilation.
- •Eye protection: Wear safety glasses when handling hot components or purging materials.
- •Secure components: Ensure all bolts are properly tightened after reassembly before resuming operation.