Addressing Abrasive Wear in GF-Reinforced PA66: Extending Maintenance Cycles with High-Hardness Alloy Screws

In the plastic modification industry, PA66 (Polyamide 66) reinforced with Glass Fiber (GF) is a critical material for automotive structural parts, electronic connectors, and industrial fasteners. However, because glass fiber possesses extreme hardness (Mohs 6-7), it exerts severe mechanical abrasion on the twin screw extruder barrel and elements during the extrusion process.

In applications involving PA66+30%GF or higher loading, the material does not simply melt and flow. The unmelted polymer pellets and rigid glass fibers, under the high shear of the screw, create a "sandblasting" effect on metal surfaces.

• Localized High Pressure: In the compression and melting zones, pressure fluctuations increase the normal force between the fibers and the metal walls.

• Physical Scratches: Fiber fragments embed into the screw flights, causing the clearance accuracy to widen rapidly from the standard $0.02text{ mm}$.

To extend maintenance cycles, one must focus on the extruder barrel material and hardness grades. Traditional nitrided steel (38CrMoAlA) often fails within months as its thin nitration layer (approx.0.4-0.6mm) wears through under high-fill GF conditions.

• Bimetallic Barrels: Utilizing centrifugal casting, a 2.0-3.0mm thick high-chrome nickel-based alloy liner is applied to the inner wall.

• Screw Element Materials: WR13 or W6Mo5Cr4V2 high-speed tool steels are recommended. After vacuum quenching, the overall hardness remains stable at 58 - 64 HRC (Ref: #QC-2024-EXP-08).

When selecting screw and barrel components, technical engineers should refer to the following parameterized evidence to ensure production stability: (See table above).

For PA66+GF extrusion, choosing parts with original equipment precision is the key to reducing downtime losses. By maintaining barrel concentricity within and utilizing a Ra < 0.4μm mirror polish, manufacturers can solve quality issues like fiber exposure while significantly improving ROI.