Bimetallic Conical Twin Screw Barrel for High-Filler PVC Extrusion
Product Summary
This bimetallic conical twin screw barrel features a D2 tool steel alloy lining (HRC50-65, depth 0.8-2.0mm) on the inner surface, combined with a post-nitriding chromium plating (≥900HV, 0.025-0.10mm). Designed for extreme abrasive and corrosive environments such as high-filler PVC extrusion with CaCO3 content. The bimetallic structure significantly extends service life compared to standard nitrided barrels.
Key Selling Points
D2 Alloy Lining: Hardness HRC50-65 with lining depth 0.8-2.0mm provides exceptional resistance to abrasion from fillers like CaCO3.
Chromium Plating: Surface chromium-plating after nitriding achieves ≥900HV hardness, reducing corrosion and improving release.
Precision Fit: Screw straightness ≤0.015mm and Ra 0.4 surface roughness ensure uniform extrusion and minimal wear.
Custom Alloy Options: Available with DC53, AISI316, or 9Cr18MoV lining for specific chemical resistance.
Proven in Field: Used successfully in high-filler PVC compounding lines with 1-5 years lifetime under normal conditions.
Technical Specifications
Parameter
Value
Alloy Hardness
HRC50-65
Alloy Depth
0.8-2.0mm
Chromium-Plating Hardness (After Nitriding)
≥900HV
Chromium-Plating Depth
0.025-0.10mm
Core Hardness (After Hardening & Tempering)
HB260-310
Surface Roughness
Ra 0.4
Screw Straightness
0.015mm
Diameter Range
Φ25/50 – Φ185/340
Lining Material (Standard)
D2 (Gr12MoV equivalent)
Models and Options
Available in all conical twin-screw sizes. Lining materials can be selected from D2, DC53, AISI316, 9Cr18MoV, 440C, Inconel 718, Hastelloy C-276, and more. Chromium plating optional for additional corrosion protection.
Materials and Structure
The barrel base is made from 4140 or 42CrMo steel, with a centrifugally cast alloy lining on the internal wear surface. The lining is D2 tool steel (hardness HRC50-65, depth 0.8-2.0mm). After lining, the barrel undergoes nitriding (case depth 0.45-0.7mm) followed by chromium plating. This combined metallurgical structure offers superior wear and corrosion resistance.
Applications
Specifically engineered for extruding PVC compounds with high filler content (e.g., 30-50% CaCO3), as well as abrasive and corrosive polymers. Used in pipe, profile, sheet, and pelletizing lines where standard nitrided barrels wear out quickly.
Customization
We tailor lining alloys, thickness, and surface treatments to your specific material formulation. Provide process parameters and we recommend the optimal barrel configuration. MOQ 1 unit.
Case Study
Extrusion & Injection Machinery OEM – High-Filler Pipe Production
An OEM machine builder integrated our bimetallic conical twin screw barrel into their PVC pipe extrusion line processing 40% CaCO3 filled compound. The barrel achieved over 3 years of continuous service without measurable wear, significantly reducing warranty claims and customer downtime.
FAQ
How does bimetallic differ from nitrided barrel?
Bimetallic barrels have a thick alloy lining that provides much higher wear resistance, especially against abrasive fillers. Nitrided barrels rely on a shallow diffusion layer.
Can I get Hastelloy lining for corrosive polymers?
Yes, we offer Hastelloy C-276 and Inconel alloys for highly corrosive environments. Contact us with your requirements.
What is the typical lifetime?
Under normal high-filler PVC extrusion, expected lifetime is 1-5 years depending on filler percentage and operating conditions.
Do you offer a refurbishment service?
Yes, we can strip and re-line worn barrels. Inquire for details.
What is the delivery method?
FOB or CIF. Pre-shipment inspection is available.
How to order a custom size?
Send your drawing or detailed dimensions to info@gmscrew.com. We will quote within 24 hours.
Is your company ISO certified?
Yes, we hold ISO9001:2015, ISO14001:2015, and ISO45001:2018 for occupational health and safety.
