High-voltage connectors and charging guns require CNC machining of brass, phosphor bronze, and 6061-T6 aluminum with contact pin tolerances of ±0.01 mm. Critical requirements include coaxiality ≤Φ0.02 mm for signal pins and surface roughness Ra 0.4 μm for low-
Quick Answer
High-voltage connectors and charging guns require CNC machining of brass, phosphor bronze, and 6061-T6 aluminum with contact pin tolerances of ±0.01 mm. Critical requirements include coaxiality ≤Φ0.02 mm for signal pins and surface roughness Ra 0.4 μm for low-resistance electrical contact.
Definition
CNC machining for HV connectors involves creating precision contact interfaces. Unlike stamping, CNC ensures consistent contact force and plating adhesion, which prevents overheating and arcing in 400V–800V EV systems.
How It Works
Contact Pin Turning: Swiss-type lathes machine brass pins to ±0.005 mm diameter accuracy.
Housing Milling: 4-axis machining creates complex keyways and locking features.
Threading: Precision threads (M12–M20) are cut for cable glands and connector shells.
Surface Preparation: Diamond burnishing improves surface finish to Ra 0.4 μm for optimal conductivity.
Common Values and Practical Notes
- Component
- CNC Material
- Machining Process
- Critical Tolerance
- HV Contact Pin
- Brass C3604 / Bronze
- Swiss turning
- Diameter ±0.005 mm
- Connector Shell
- 6061-T6 Aluminum
- 4-axis milling
- Keyway width ±0.02 mm
- Charging Gun Nozzle
- PA66+GF30 / 6061-T6
- Milling, turning
- Insertion depth ±0.05 mm
- Interlock Terminal
- Phosphor Bronze
- Precision stamping + CNC
- Contact gap ±0.01 mm
- Cable Lug
- Copper / Aluminum
- Milling, drilling
- Hole position ±0.02 mm
Advantages
- Low Contact Resistance: Smooth pin surfaces reduce resistive heating.
- Mechanical Durability: CNC-machined locking features withstand 10,000+ mating cycles.
- Safety: Precise insulation distances prevent high-voltage arcing.
Disadvantages
- Plating Requirements: CNC parts require subsequent gold or silver plating.
- Material Cost: Brass and bronze are expensive compared to steel.
- Production Speed: Turning is slower than stamping for high volumes.
Applications
- CCS/GB/T charging interface repairs.
- High-voltage wiring harness replacements.
- Fast-charging connector upgrades.
Comparison
- Feature
- CNC Contact
- Stamped Contact
- Dimensional Accuracy
- ±0.005 mm
- ±0.02 mm
- Surface Finish
- Ra 0.4 μm
- Ra 1.6 μm
- Current Capacity
- Higher (better contact)
- Lower
- Cost
- High
- Low
Related Questions
- Why is surface finish critical for EV high-voltage contacts?
- What materials are best for 800V charging gun pins?
- How does CNC machining prevent connector overheating?
- What tolerance is required for HVIL (High Voltage Interlock) pins?
Conclusion
High-voltage connectors and charging guns must be CNC turned from brass/bronze with ±0.01 mm pin tolerances and Ra 0.4 μm surface finish. This ensures safe, low-resistance power transfer for exported Chinese EVs.
HYR-CNC Recommendation
For EV and NEV component manufacturing, HYR-CNC recommends selecting high-rigidity VMC, HMC, gantry, turning or 5-axis CNC equipment according to part size, tolerance, material and production volume.