In the field of twin screw extrusion, the performance and durability of screw elements are directly linked to their material properties. Selecting the right wear- and corrosion-resistant materials is crucial to maintaining product consistency, reducing maintenance costs, and extending equipment service life.
This guide explores the main material types used for twin screw extruder screw elements, their characteristics, and how to choose the right one for your production environment.
1. Why Material Selection Matters
Screw elements are constantly exposed to high shear, friction, and chemical attack. The wrong material choice can lead to rapid wear, poor mixing performance, and downtime due to frequent replacement.
Key performance factors affected by material selection include:
- Wear resistance under abrasive fillers or glass fiber
- Corrosion resistance when processing reactive or acidic compounds
- Thermal stability at high extrusion temperatures
- Dimensional accuracy and mechanical toughness
Choosing the right material helps ensure consistent compounding quality and lowers overall operating costs.
2. Common Wear- and Corrosion-Resistant Materials
| Material |
Hardness (HRC) |
Wear Resistance |
Corrosion Resistance |
Characteristics |
Typical Applications |
| W6Mo5Cr4V2 (High-Speed Tool Steel) |
63–65 |
★★★★☆ |
★★☆☆☆ |
High hardness, good wear resistance, moderate corrosion resistance |
Engineering plastics, glass fiber compounding |
| 38CrMoAl (Nitrided Steel) |
58–60 |
★★★☆☆ |
★★★☆☆ |
Balanced toughness and surface hardness after nitriding |
General-purpose extrusion and compounding |
| Cr12MoV (Tool Steel) |
60–62 |
★★★★☆ |
★★☆☆☆ |
Excellent wear resistance, moderate toughness |
Filled plastics, abrasive additives |
| SKD61 (Hot Work Tool Steel) |
56–58 |
★★★☆☆ |
★★★★☆ |
Great heat resistance and oxidation stability |
High-temperature extrusion applications |
| PM-HIP Grades (SAM26 / SAM39 / CPM10V / CPM9V) |
64–67 |
★★★★★ |
★★★★☆ |
Uniform microstructure, outstanding wear and corrosion resistance |
Harsh wear or corrosive conditions |
| 440C Stainless Steel |
56–58 |
★★☆☆☆ |
★★★★★ |
Excellent corrosion resistance, moderate hardness |
Chemical and food-grade extrusion environments |
3. Matching Materials to Extrusion Conditions
Different materials perform best under specific working environments:
| Extrusion Condition |
Recommended Material |
Performance Notes |
| High filler loading |
W6Mo5Cr4V2 or CPM10V |
Excellent wear resistance under high shear |
| Corrosive compounds (chlorine, halogen, flame retardant) |
440C or SAM39 |
High corrosion resistance with stable structure |
| Balanced wear + corrosion |
SAM26 or CPM9V |
Ideal for most engineering plastics |
| High-temperature extrusion |
SKD61 or SAM39 |
Maintains mechanical strength under heat |
| Standard compounding |
38CrMoAl |
Cost-effective and reliable |
4. Material Processing and Heat Treatment
At ZHITIAN, each screw element undergoes precision CNC machining and controlled heat treatment to ensure uniform hardness and dimensional stability.
Key steps include:
- Vacuum heat treatment for precise hardness control
- Cryogenic stabilization to prevent internal stress
- CNC finishing for geometric precision within ±0.02 mm
- Surface treatment options such as nitriding or hard coatings for added durability
This ensures each element maintains consistent performance, even under long-term operation in demanding extrusion environments.
5. How Material Choice Impacts Extruder Performance
Proper material selection directly enhances:
- Extruder lifespan – reduces wear on both screw and barrel
- Energy efficiency – smoother torque transfer and lower friction
- Product stability – uniform shear rate and consistent melt quality
- Maintenance cost – fewer replacements and longer intervals
For high-output, precision compounding lines, upgrading to PM-HIP or high-speed tool steel elements can improve both reliability and productivity.
6. ZHITIAN’s Expertise in Material Engineering
With over 20 years of specialization in twin screw extruder parts, ZHITIAN provides screw elements, barrels, and gearboxes designed for extreme performance.
Our engineering team selects optimal material combinations based on application type, material formulation, and operating parameters, ensuring durability and cost-effectiveness.
7. Conclusion
Selecting the right wear- and corrosion-resistant screw element material is essential for maintaining extrusion stability and minimizing downtime.
From nitrided steels like 38CrMoAl to PM-HIP alloys such as SAM26 and CPM10V, ZHITIAN offers customized solutions to match every processing challenge — achieving longer service life, higher productivity, and consistent quality.
FAQ
Q1: What’s the best material for both wear and corrosion resistance?
A1: PM-HIP materials such as SAM26, SAM39, and CPM10V provide the best overall performance, combining high hardness with corrosion stability.
Q2: How can I identify if my process needs corrosion-resistant materials?
A2: If your extrusion process involves additives like chlorine, bromine, or flame retardants, corrosion-resistant materials such as 440C or PM-HIP grades are strongly recommended.
Q3: Can ZHITIAN customize screw elements for my extruder?
A3: Yes. ZHITIAN offers full OEM and custom design services based on samples or technical drawings.
Q4: How much longer does a PM-HIP screw element last compared to nitrided steel?
A4: On average, PM-HIP screw elements last 3–5 times longer in abrasive or corrosive environments.
Q5: Are there material options for food or chemical extrusion lines?
A5: Yes. Stainless steels such as 440C and special PM alloys are suitable for hygienic and chemically reactive processing conditions.
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