When customers search for UHMWPE rod, UHMWPE sheet, or UHMWPE tube, one of the most frequently asked questions is:
“Should I choose ram extruded UHMW-PE or screw extruded (single-screw) UHMW-PE?”
The answer is not just about price — it directly affects wear resistance, impact strength, molecular chain integrity, and final part lifetime.
Below is a detailed professional comparison based on 32 years of actual production experience at Skyjet Polymer.
| Parameter | Ram Extruded UHMW-PE (Press-Ram) | Screw Extruded UHMW-PE (Single/Twin Screw) | Winner |
|---|---|---|---|
| Molecular Weight Capability | Up to 9.2 million g/mol (GUR 4150 / GUR 4170) possible | Usually limited to ≤ 5 million g/mol | Ram |
| Shear Force During Processing | Almost ZERO shear – material is pushed, not cut | High shear force from screw → chain scission | Ram |
| Molecular Chain Integrity | 100% preserved | 15–35% molecular weight loss (proven by GPC testing) | Ram |
| Wear Resistance (Sand-Slurry) | Highest – up to 30% better than screw extruded | Good, but noticeably lower | Ram |
| Impact Strength (-40°C) | Excellent, no brittle failure | Reduced due to shorter chains | Ram |
| Internal Stress | Extremely low → parts stay flat after machining | Higher residual stress → warping possible | Ram |
| Surface Finish | Mirror-like smooth (Ra < 0.3 μm) | Slight screw marks possible | Ram |
| Diameter/Thickness Range | Rod up to Ø350 mm, sheet up to 200 mm thick | Usually limited to ≤ Ø180 mm / 100 mm thick | Ram |
| Production Speed | Slower (but quality first) | Faster | Screw |
| Price | 8–15% higher | Lower | Screw |
Why Ram Extrusion Is the Only Real Choice for Ultra-High Molecular Weight (9+ Million) UHMW-PE
UHMW-PE with molecular weight ≥ 9 million (such as Teijin GUR 4150, Celanese GUR 4170) is extremely viscous — it behaves more like a solid powder than a melt.
A traditional screw extruder generates tremendous shear heat (>280°C) and mechanical cutting force. The long molecular chains are literally “chopped” by the screw flights, resulting in:
- 15–35% molecular weight drop (verified by Gel Permeation Chromatography)
- Reduced abrasion resistance
- Lower notch impact strength
- Higher risk of stress cracking after years in service
Only ram extrusion uses a hydraulic press to push the powder directly into the die with almost zero shear. This is the reason why Skyjet Polymer is one of the few factories in the world that can truly produce genuine 9.2 million molecular weight GUR4150 products without degrading performance.
Real Performance Data from Our Laboratory (2024-2025)
| Test Item | Skyjet Ram Extruded GUR4150 | Typical Screw Extruded 3–5M | Improvement |
|---|---|---|---|
| Molecular Weight (GPC) | 9.2 million g/mol | 3.8–4.8 million g/mol | +92–142% |
| Abrasion Loss (mg/1000 cycles) | 6.8 mg | 11.2 mg | +39% better |
| Izod Impact Strength (kJ/m²) | No break | 98–115 kJ/m² | Infinite |
| Coefficient of Friction (vs steel) | 0.08–0.10 | 0.11–0.14 | 20–30% lower |
When Should You Choose Ram Extruded UHMW-PE?
Choose ram extruded if your application involves:
- Heavy-duty conveyor wear strips
- Marine fender facing pads
- Large-diameter crane outrigger pads
- Food-grade scraper blades that require FDA compliance + extreme wear life
- Nuclear/medical components that cannot afford any chain degradation
Choose screw extruded only if budget is extremely tight and the part is non-critical.
Skyjet Polymer – Your Trusted Ram Extrusion Partner
At Skyjet, we operate three German-made ram extrusion lines dedicated to GUR 4150/4170 ultra-high molecular weight resin. All of our:
are produced with zero shear degradation and come with original Celanese/Teijin material certificates + our own GPC test reports.
Ready to upgrade from ordinary screw-extruded UHMW-PE to genuine 9.2 million molecular weight performance?
→ Get Free Quote & Sample Within 24 Hours
Or download our latest UHMWPE Ram vs Screw Comparison PDF here:
Download Technical Whitepaper (2025 Edition)
Any questions? Drop them in the comment or contact our engineering team directly — we speak fluent English, German, and Arabic.
Skyjet Polymer – When molecular weight and real performance matter.