Electric Motor Housings CNC Machining for EV Powertrains

A380 cast aluminum performs outstandingly well when it comes to casting complex shapes and configurations, and can produce wall thicknesses ranging between 3 and 8 millimeters in one single casting. Also, it can create cooling jackets and internal passageways that can reduce secondary machining operations by 40 to 60 percent in cooling jackets. Its thermal conductivity is at 96 watts per meter kelvin, which aids in cooling down the heat generated by the stator windings of the motor with 2 to 5 kilowatts of continuous loss, and can assist in still maintaining cost-efficient production with cycle times between 60 to 180 seconds for housings with production volumes exceeding 50,000 units annually. 6061-T6 aluminum has higher strength and better machinability, which assists in creating bearing bores of the desired specification with a 5-25 kilonewton bearing load, which is applied during acceleration and regenerative braking. This yield strength of 276 megapascals aids 6061-T6 aluminum in supporting bearing loads during braking. Also, 6061-T6 aluminum has additional thermal conductivity of 167 watts per meter kelvin.
Cast iron GG-25 provides outstanding vibration dampening, with a damping capacity that is 10-20 times that of aluminum, reducing noise, vibration, and harshness by 5-10 decibels. It provides superior electromagnetic shielding with magnetic permeability that attenuates electromagnetic interference. GG-25 maintains dimensional stability while bearing alignment is thermally cycled through -40°C to +150°C. It has proven reliability in traction motors for commercial vehicles and industrial applications with service lives exceeding 15 years.

Horizontal CNC machining centers with work envelopes of 800 to 1500 millimeters use precision boring heads to machine bearing bores, achieving tolerances of ±0.005 millimeters on diameter and 0.010 millimeters concentricity over spans of 200 to 500 millimeters for rotor bearings that operate at 8,000 to 18,000 RPM. Multi-axis CNC milling accomplishes the required mounting flange surfaces with a flatness of 0.010 millimeters over 250 to 450 millimeter diameter spans. The internal surfaces of the stator cavity are finished with a cylindricity of 0.020 millimeters to control the electromagnetic airgap of 0.5 to 1.5 millimeters and 0.5 to 1.5 millimeters, and the passages of the cooling jackets are accurately finished to ±0.005 inches. CNC drilling and tapping are used to finish mounting the holes, which have position accuracy of ±0.015 millimeters for standardized interfaces of the powertrain, coolant ports with threads of sizes M8 to M16, and sensor mounting provisions with perpendicularity of 0.020 millimeters. The honing of bearing bores is finished with a diameter control of ±0.003 millimeters for press-fit installation of the bearing with an interference of 0.015 to 0.040 millimeters and a surface finish of Ra 0.4 to 0.8 microns. High-pressure die casting creates the aluminum housings at 640 to 680 degrees centigrade with cycle times of 60 to 180 seconds, which contain injection, solidification, and ejection phases.
The final machining tolerances achieved after T5 or T6 post-casting heat treatment diminish the residual stress and provide dimensional stability of ±0.025 millimeters after machining and 4 to 8 hours of treatment between 150 °C to 180 °C.

The tolerances for the bearing bore diameter are ±0.005 millimeters to fit the bearing precisely to prevent bearing creep during thermal expansion cycles, and with a designed interference of 0.015 to 0.040 millimeters, bore concentricity is within 0.010 millimeters over bearing spans of 200 to 500 millimeters. Rotor runout of 0.050 millimeters is achieved at 10,000 to 15,000 RPM to prevent electromagnetic imbalance and vibration. For the stator, cavity cylindricity is within 0.020 millimeters, and the designed electromagnetic airgap uniformity of ±0.100 millimeters to improve torque production and reduce cogging torque. Mounting flange flatness is controlled within 0.010 millimeters, which aids frame distortion during torque transfer of 200 to 400 Newton-meters. For the cooling jacket, channel dimensions are controlled to within ±0.005 inches to maintain the designed flow distribution and pressure drop of 0.3 to 1.0 bar at flow rates of 15 to 25 liters per minute. Perpendicularity within 0.015 millimeters between bearing bores, channel surfaces, and mounting surfaces helps lessen misalignment of the shaft and ultimately reduces bearing L10 life to 8,000 hours of operation.

Yes, Zintilon supports both prototyping and production volumes. Zintilon has rapid prototyping capabilities, delivering 3 to 12 functional prototypes within 4 to 6 weeks for electric motor testing and final thermal validation testing, including dynamometer testing at both rated and peak power conditions. Zintilon has low-volume production capabilities, producing between 100 and 1,500 motor housings for pre-production vehicles and specialty applications tailored to documented first article inspection and production part approval processes, and then high-volume production with more than 30,000 housings a year for mass-market electric vehicles, using automated manufacturing cells and SPC with process capability indices for critical dimensions bearing bores exceeding 1.67 Cpk. Each phase of production bears comprehensive process validation including CMM inspection of bearing bore concentricity and mounting interface flatness, pressure testing of cooling jackets at 1.5 times max operating pressure (8 to 12 bar) for leak performance outlined via helium leak detection (sensitivity 1×10⁻⁶ ml-1 sec-1), measuring surfaces of bearing bores for precision roughness (Ra 0.4 to 0.8 microns) and documenting thermal cycling from -40 to +150 for 500 cycles, and testing for IATF 16949.

We produce housings following IATF 16949:2016 standards, automotive quality management systems with production part approval process compliance, and advanced product quality planning documentation. Housings comply with UN ECE R10 electromagnetic compatibility standards for electric vehicle traction motors and limit radiated emissions to 30 to 40 decibels microvolts per meter within 30 to 1000 megahertz. Housings comply with ISO 16750 environmental testing standards for automotive components and vibration resistance with 10 to 50g and 10 to 2000 hertz, and thermal shock transitions at -40°C and +125°C. Housings also meet IP67 ingress protection standards per IEC 60529 for underbody installations and prevent water ingress during 1 meter immersion for 30 minutes. Additional standards and certifications include: UL 2202 standards for electric vehicle drive units, innovation to your shelter, and electrical insulation resistance (> 500 megohms), dielectric strength (2000 volts AC for 1 minute), and 1 minute at 2000 volts AC dielectric strength, ASME Section VIII Division 1 pressure vessel standards to for cooling jackets, and safety standards for bettle 5 to 10 Bar operating pressure.
The processes of manufacturing include the use of non-destructive testing employing x-ray inspection of critical cast sections for the detection of porosity surpassing 3%, dye penetrant inspection of machined surfaces for the identification of surface-breaking defects greater than 0.1 millimeters, verification of dimensions according to the engineering specifications and tolerances detailed on the control plans, and the assessment of empirical verification including the assurance of electromagnetic performance, the provision of thermal management of 3 to 8 kilowatts continuous heat dissipation, and structural integrity for the entire 200,000 to 300,000 kilometers service life of the vehicle.

For surface finishing, options available for finishing include powder coating with epoxy or polyester formulations achieving 60 to 100 micron dry film thickness and providing corrosion resistance and electrical insulation on external surfaces, Type II anodization for 10 to 25 micron oxide layer for aluminum housings which enhances corrosion protection and provides electrical isolation resistance over 1000 megohms, electroless nickel plating with thickness 5 to 15 microns on aluminum components which improves wear resistance and provides barrier corrosion protection on areas that are coolant-exposed, chemical conversion coating per MIL-DTL-5541 which creates 0.5 to 1.5 micron chromate or non-chromate layer which enhances paint adhesion and provides temporary corrosion protection during assembly, and electrocoating cathodic e-coat with thickness 15 to 25 microns which ensures complete coverage in areas recessed in cooling jackets and in bolt holes. Passivation treatment is applied to the internal cooling jacket's surface to enhance corrosion protection. Aluminum oxidation during the use of a glycol-water coolant mixture, 40 to 60 percent concentration, with pH 7 to 9, is controlled to extend the service life of the coolant 5 to 10 years. Bearing bore surfaces are preserved as-machined finish Ra 0.4 to 0.8 microns and without secondary coating to retain dimensional accuracy and bearing press-fit integrity.

For standard die-cast aluminum housings for motors in the 80 to 150 kilowatt range, we have lead times of 8 to 12 weeks. This is for production lots of 500 to 2,000 units and covers casting production, heat treatment, CNC machining, finishing, and quality checks. For custom-fabricated housings with extensive machining and other added processes like welding, it may take up to 10 to 16 weeks. This is highly dependent on the complexity and may include validation tests like thermal and vibration checking. We can provide rapid-turn prototypes in 4 to 6 weeks with expedited machining and basic finishing. For high-volume production of 20,000 housings per year, we need 16 to 24 weeks for the initial setup in diecasting tooling, which can cost between 50,000 and 50,000and150,000 and including the development of CNC machining fixtures, completion of the production part approval process, and the integration of automated inspection tools aligned with vehicle assembly schedules for controlled deliveries. The lead time for production orders is phased to vehicle assembly production schedules.

Absolutely, we design integrated transaxle housings that combine the electric motor enclosure with the single-speed gearbox casing into a unified component reducing assembly mass by 10 to 18 kilograms and eliminating 6 to 10 sealing interfaces, dual-motor housings for all-wheel-drive configurations supporting 100 to 250 kilowatt per axle motors with shared cooling system that reduces component count by 20 to 30 percent, high-speed motor housings for 15,000 to 25,000 RPM motors with enhanced bearing support using angular contact bearings in back-to-back arrangements and critical speed analysis that prevents resonance vibration, oil-cooled housings with integrated spray cooling nozzles delivering 2 to 6 liters per minute directly onto stator end-windings, and achieving 1000 to 3000 watts per square meter Kelvin heat transfer coefficients, and specialty configurations including motorsport housings that use magnesium alloy or carbon fiber composite to reduce mass 30 to 50 percent for racing applications, commercial vehicle housings for traction motors 200 to 400 kilowatts in buses and trucks with enhanced structural reinforcement and IP67 sealing for underbody mounting, aerospace grade housings for electric aircraft propulsion with mass optimization achieving power-to-weight ratios 5 to 8 kilowatts per kilogram, and marine-rated housings with enhanced corrosion protection for electric boat propulsion motors 50 to 300 kilowatts.

Precision machining contributes to optimal performance by bearing bore concentricity being held to within ±0.010 millimeters over spans of bearings. This achieves a reduction in rotor eccentricity that results in a rise of electromagnetic losses by 5 to 15 percent. It also minimizes vibrations at the fundamental frequency of 150 to 300 hertz for motors that operate at 9,000 to 18,000 RPM. Accurate machining of the stator cavity to a cylindricity of within ±0.020 millimeters contributes to the uniformity of the electromagnetic airgap of 0.6 to 1.2 millimeters, thereby preventing a torque ripple of more than 5 percent and sustaining the motor efficiency at 92 to 96 percent across the 1,000 to 15,000 RPM operating range. Consistent control of the bearing bore diameter within ±0.005 millimeters also enables the proper press-fit installation of the bearing with an interference of 0.020 to 0.035 millimeters, which prevents the bearing from loosening due to thermal expansion cycles, vibration loads, and ensures the bearing L10 life exceeds 10,000 hours at the rated load. Accurate machining of the cooling jacket channel to within ±0.005 inches contributes to the preservation of designed coolant flow, thereby preventing stator winding hot spot temperatures from rising beyond Class F 155°C, which increases motor life from 8 to 15 years by preventing insulation degradation.
Over a period of 10 to 15 years, a well-executed surface finish will act as a barrier to corrosion, preserve structural integrity, and afford electromagnetic shielding in a highly variable environment consisting of underbody road salt sprays, coolant concoctions with corrosion inhibitors and pH 7 to 9 buffers, highly glycolous thermal baths ranging from -40º and 150ºC, and variable frequency vibrations of 5 to 50g at 10 to 2000 Hz. The surface finish will enable dependable performance of motor enclosure in powertrains of electric vehicles during continuous operation at 60 to 250 kilowatts with a peak burst of 120 to 400 kilowatts for 10 to 30 seconds, torque from 150 to 600 Newton-meter at 0 to 3,000 RPM, thermal losses of 3 to 8 kilowatts with winding at 100 to 140°C, and service life of the vehicle will exceed 200,000 kilometers while 50 to 400 kilowatts rated motor in commercial trucks, 500,000 kilometers, and buses with 8,000 to 12,000 operational hours will furthermore equip motor rated from 50 to 400 kilowatts as well.