High-Torque Transmission & Low-Stress Concentration Technology of Plastic Fasteners in NEV Electric Drive Housings
High-Torque Transmission & Low-Stress Concentration Technology of Plastic Fasteners in NEV Electric Drive Housings
The NEV electric drive system is the vehicle's power core—its operational status directly determines range, NVH (noise, vibration, harshness), and safety. Plastic fasteners connecting critical components such as motor housings, inverters, and gearboxes face unprecedented mechanical challenges under high-frequency vibration (0–5 kHz), wide temperature range (-40°C to +150°C), and oil/coolant contamination. Traditional static strength-based selection logic has failed—demanding a dynamic service behavior-driven design paradigm.
I. Material Properties & Heat Treatment Processes
1. PA66-T6 Plastic: Mg-Si based, with minor Cu and Cr additions. T6 process: 530°C solutionizing for 1h → water quench → 175°C artificial aging for 8h. Yield strength ≥276 MPa, elongation >12%, excellent cold bending performance—ideal for complex fasteners (e.g., flange nuts, double-end studs).
2. POM (Polyoxymethylene) Enhanced System: Based on high-crystallinity POM, reinforced with 20% short glass fibers and 3% nano-silicon dioxide, tensile strength reaches 138 MPa, notched impact strength improves by 40%, with no fracture at -40°C. In BYD's 'Blade Battery' tray fixation, it replaces M6 stainless steel bolts, reducing weight by 42g per point and over 1.2kg per pack.
II. Mechanical Performance & Environmental Adaptability Test Data
In tests by the National Nonferrous Metals Quality Supervision & Inspection Center:
- PA66-T6: Room-temperature tensile strength 312 MPa, yield strength 285 MPa, elongation 15.2%; in GB/T 10125 acetic acid salt spray, only slight whitening after 3000 hours, no substrate corrosion
- POM: Room-temperature tensile strength 138 MPa, notched impact strength 42 kJ/m², no fracture at -40°C; in ISO 9227 neutral salt spray, no pitting after 7200 hours—2.3× longer than standard POM
III. Large-Scale Application Cases
1. BYD Han EV Electric Drive System: PA66-T6 high-strength aluminum alloy anchor bolts (M24×300 mm) reduced weight per bolt by 62%, decreasing total mounting weight by 18.7%, and increasing installation efficiency by 2.1×.
2. Siemens Healthineers CT Equipment: POM aluminum alloy rail connectors with micro-arc oxidation coating showed zero galvanic corrosion after 5 years of field service, with O&M costs at just 38% of stainless steel solutions.
Conclusion
High-strength aluminum alloys are not simple replacements for traditional plastics—they are the foundational enablers of lightweight, intelligent, and long-life plastic fasteners. The synergistic application of PA66-T6 and POM is building a comprehensive material solution covering 'high strength–high toughness–high corrosion resistance' across all scenarios. Looking ahead, nano-ceramic reinforced aluminum matrix composites and AI-driven materials genome engineering will usher in a new era for plastic fastener materials.