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CNC Machined Aluminum 6061 EV Motor Housing with Leak-Tight Coolant Passages and 0.02mm Stator Bore Precision

CNC Machined Aluminum 6061 EV Motor Housing with Leak-Tight Coolant Passages and 0.02mm Stator Bore Precision

Detail Information
Material:
Al 6061-T6
Stator Bore Roundness:
0.02mm Max
Mounting Face Flatness:
0.01mm Max
Coolant Test Pressure:
2 Bar (30 PSI)
Surface Treatment:
Anodized Type II
Tolerance:
+/-0.01mm (stator Bore, Mounting Face)
Product Description
CNC Machined Aluminum 6061 EV Motor Housing for Electric Vehicles
Product Overview

EV motor housings represent one of the most demanding aluminum components we machine. While appearing deceptively simple externally, these housings require exceptional precision in critical areas including stator bore roundness, mounting face flatness, and leak-tight coolant passages. We machine these housings from Al 6061-T6 billet rather than castings to ensure zero porosity, consistent mechanical properties, and superior tolerance control.

Key Features
  • Stator Bore Precision: Roundness within 0.02mm, cylindricity within 0.03mm, surface finish Ra 1.6 - critical for maintaining proper air gap between stator and rotor
  • Mounting Face Flatness: 0.01mm flatness on transmission mounting face with perpendicularity to stator bore within 0.02mm
  • Coolant Passage Integrity: Internal passages machined by CNC drilling/milling, leak tested at 2 bar (30 PSI) for 10 minutes with zero leaks accepted
  • Threaded Hole Pattern: M5 or M6 bolt circles (36-48 holes) with position accuracy ±0.05mm relative to stator bore centerline
  • IATF 16949 Process Control: Full PPAP capability with process FMEA, control plans, SPC on critical dimensions, and MSA on measurement equipment
Technical Specifications
Specification Details
Product Name CNC Machined Aluminum 6061 EV Motor Housing
Material Options Al 6061-T6 (standard), Al 6061-T651 (stress relieved), Al 7075-T6 (high performance)
Tolerance ±0.01mm (stator bore, mounting face), ±0.05mm (bolt holes)
Stator Bore Roundness 0.02mm max
Mounting Face Flatness 0.01mm max
Coolant Test Pressure 2 bar (30 PSI), 10 min hold
Surface Treatment Anodized Type II (black), Hard anodize Type III (coolant passages), Powder coat
Certifications ISO 9001:2015, IATF 16949, RoHS, CE, REACH
Lead Time - Prototype 7-10 days
Lead Time - Production 15-25 days
MOQ 1 piece (prototype), 100+ (production)
Origin Dongguan, China
Applications
  • EV Traction Motors: Main drive motor housings for BEV and PHEV applications
  • E-Axle Integrated Motors: Motor housings integrated with single-speed reduction gearbox
  • EV Auxiliary Motors: HVAC compressor, power steering, and brake booster motor housings
  • Electric Motorcycle/Scooter: Hub motor and mid-drive motor housings
  • Industrial Electric Motors: High-efficiency IE4/IE5 motor housings and servo motor housings
  • E-Bike/E-Scooter: Mid-drive and rear hub motor housings
Why Choose Our Manufacturing
  • EV Motor Housing Expertise: Extensive experience machining housings from 80mm to 300mm diameters
  • Billet Machining: Zero porosity risk with consistent material properties from certified Al 6061-T6 bar stock
  • Comprehensive Leak Testing: Every housing pressure tested with 2 bar air pressure and 10-minute minimum hold
  • Advanced Machining Capabilities: 4-axis and 5-axis CNC centers for maximum accuracy and minimum setups
  • Automotive Compliance: IATF 16949 certification with PPAP Level 1-3 capability
  • Thermal Management Expertise: Optimized coolant passage design review during DFM process
Manufacturing Process
  1. DFM Review: Comprehensive design analysis including tolerance assessment, wall thickness evaluation, and coolant passage design review
  2. Material Procurement: Certified Al 6061-T6 extruded or forged billet with material certificates
  3. CNC Machining: 4-axis roughing, single-setup boring, face milling, drilling/tapping, and coolant passage milling
  4. Coolant Passage Sealing: Threaded plugs, press-fit caps, or welded closures with integrity verification
  5. Surface Treatment: Anodizing, hard anodizing, or powder coating applications
  6. Inspection & Testing: CMM full layout, leak testing, surface finish verification, and PPAP documentation
Frequently Asked Questions
Why machine from billet instead of die casting?
Consistency. Die-cast housings can have porosity in coolant passage walls, which causes leaks. The material properties of cast aluminum are less predictable than wrought (6061-T6). Billet machining eliminates porosity risk and provides tighter tolerance capability.
Can you hold 0.02mm roundness on a 250mm stator bore?
Yes, in a single setup. We bore the stator bore after roughing external features using a single-point boring bar on a CNC machining center. The key is proper fixturing that supports the part without distortion and finishing with light DOC to minimize cutting forces.
What coolant passage designs can you machine?
Cross-drilled passages (simplest, most reliable), milled spiral channels (better heat transfer), or combinations. We recommend cross-drilled for most applications as they're easier to seal, inspect, and provide adequate thermal performance for most EV motor duty cycles.
Do you do the complete sub-assembly?
We machine the housing body, install and seal coolant passage plugs, and leak test. Stator installation, rotor bearing pressing, and end bell assembly are typically done at the motor manufacturer. Partial sub-assembly available on request.
What's the lead time for first article?
7-10 days for a billet-machined prototype housing. PPAP documentation adds 5-7 days. Production tooling requires 10-15 days. Ongoing production after first article approval is 15-25 days per batch.
Can you machine the matching gearbox housing too?
Yes. Many EV e-axle designs integrate motor and gearbox in common housing or have direct bolt-on configurations. We can machine both and ensure mating surfaces match perfectly using same fixture reference and inspection datum.