Hub wheel motor Manufacturing Process Flow

HUB Wheel motor manufacturing process

1. HUB WHEEL MOTOR Rahul Venkatesh - 3122221002091 Mandati Sai -3122223001060 Rotor Assembly Stator Assembly Final Assembly

2. INTRODUCTION A hub wheel motor is an integrated electric motor embedded directly into the wheel hub of a vehicle, typically used in electric bikes, scooters, and electric vehicles. This design eliminates the need for a traditional drivetrain, offering a more efficient and compact solution for propulsion. Hub wheel motors provide benefits like reduced weight, increased space efficiency, and simplified mechanical systems. They deliver direct power to the wheel, enhancing responsiveness and contributing to improved energy efficiency in electric transportation. This technology is gaining popularity in the shift towards more sustainable and innovative mobility solutions. AMPERE Primus TVS iQube The company is a leading supplier of hub wheel motors to prominent electric vehicle manufacturers, Ampere and TVS, for their EV two-wheeler vehicles. To meet the specific requirements of each client, the company has established two separate, dedicated final assembly lines — one for Ampere and another for TVS. These segregated assembly lines ensure that the production process for each brand is tailored to meet their unique specifications and quality standards.

3. STATOR MANUFACTURING PROCESS FLOW

4. 1. Traceability Marking 2. Insulation Paper Insertion The traceability marking process for the stator core of a hub motor involves preparing the stator by cleaning and positioning it, followed by applying permanent identification marks (e.g., part numbers, serial numbers, and batch codes) using methods like laser etching or inkjet printing. The markings ensure accurate tracking throughout the manufacturing and assembly stages. After traceability marking, insulation paper is carefully inserted into the stator core slots to prevent electrical shorts and ensure proper insulation. The paper is typically cut to size and positioned accurately within the core's laminations. This step is crucial for maintaining the motor's efficiency and safety during operation. The insulation is inspected to ensure no gaps or misalignment before proceeding to the next assembly stage.

5. 3. Stator Coil Winding 4. Wedge Pad Insertion The stator coil winding involves carefully winding copper wire around the stator core’s slots to form coils. These coils are wound in layers to ensure efficient electrical conductivity and optimal magnetic field generation. Tension and alignment are monitored to prevent wire damage or misplacement. Once the winding is complete, the coils are secured to prevent movement during operation. The process is crucial for achieving the desired performance and efficiency of the hub wheel motor. Wedge pad insertion is the process of placing insulating wedge pads into the stator slots to secure the wound coils in place. These pads are carefully inserted to hold the coils tightly and prevent any movement or shifting during operation. The wedge pads also provide additional insulation, helping to prevent electrical shorts and enhance the overall stability of the stator. Once inserted, the pads are pressed into position to ensure proper coil alignment and secure the coils within the stator slots.

6. 5.Varnishing 6. Coil Enamel Stripping Varnishing is the process of applying a protective coating to the stator coils to enhance insulation and prevent electrical shorts. In this process, a mixture of varnish and catalyst is used, which helps to improve the curing speed and adhesion of the varnish to the coils. The varnish is carefully applied, ensuring complete coverage of the coils, while the catalyst accelerates the hardening process, making the insulation durable and resistant to heat and moisture. Once applied, the stator is typically cured in an oven to fully harden the varnish and provide long-lasting protection. Coil enamel stripping is the process of removing the enamel coating from the ends of the stator coils to allow for proper electrical connections during the assembly process. The enamel coating is stripped using mechanical or chemical methods, such as abrasive tools, solvents, or specialized stripping equipment. This ensures that the copper wire is exposed and ready for soldering or connecting to other components. Care is taken to avoid damaging the wire or affecting the insulation on the rest of the coil.

7. 7. Core and Shaft Assembly 8. P Coil Twisting In the core and shaft assembly process for the stator of a hub motor, the operator first checks that the shaft is of the specified size to ensure proper fit. The operator then places the stator core into the machine and manually inserts the shaft into the core. Once the shaft is positioned correctly, the machine takes over to securely fix the shaft into the core, ensuring a tight and precise assembly. This automated process ensures the shaft is firmly held in place, providing stability and ensuring optimal motor performance. In the phase coil twisting process, the operator first manually twists and joins the first and third windings with the second winding to create the desired coil shape. Once this is done by hand, the coils are placed into a machine, where three tube-like structures automatically align with the wires. These tubes then insert into the coils and apply the necessary twisting motion, tightly securing the P-shaped coil configuration. This automated process ensures precise twisting and consistent coil formation, critical for the stator's performance in the hub motor.

8. 9. N Coil Twisting 10. P&N Coil Trimming In the neutral coil twisting process, the operator manually twists and joins the first and third windings with the second winding to ensure proper alignment. After this, the operator places the coils into the machine, where three tube-like structures automatically position themselves around the wires. These tubes then insert themselves into the coils, applying the necessary twisting action to secure the windings and ensure uniformity. This automated process ensures that the coils are tightly twisted and properly configured for optimal motor performance. The stator is then transferred to the coil trimming machine, where the coils are securely clamped in place. The machine precisely trims any excess wire length, ensuring the coils are cut to the exact required size. This step ensures the coils fit perfectly within the stator slots and are ready for proper electrical connections. It eliminates any surplus wire, preventing interference during assembly and optimizing the motor's overall performance.

9. 11. P&N Coil Welding 12. P&N Coil Soldering In the P and N coil welding process, the twisted coil stator is fed into the machine, where welding is performed on the coil ends. The machine precisely applies heat to fuse the coil wires, creating strong and reliable electrical connections between the P and N phase coils. This process ensures that the coils are securely connected, preventing any loose connections that could affect the motor’s efficiency and performance. After welding, the stator is ready for further assembly and testing. For P and N coil soldering, dip soldering is used to create secure electrical connections. First, the coils are dipped into a cleaning transparent solution to remove impurities and ensure proper solder adhesion. After cleaning, the coils are immersed in a soldering solution, which is heated to around 300°C. The entire process is carried out in a machine, ensuring consistent and precise soldering. This method provides strong, reliable connections between the coils, ensuring optimal performance and durability of the motor.

10. 13. Sleeve Shrinking 14. Hall sensor and PCB soldering A black HS (heat shrink) sleeve is inserted into the soldered windings, and using a hot gun, the operator carefully heats the sleeve. The heat causes the sleeve to shrink tightly around the soldered area, ensuring secure insulation and protection for the windings. This process helps prevent electrical shorts, improves the mechanical stability of the coils, and provides additional insulation for the motor’s durability and performance. Once the sleeve has fully shrunk, it creates a tight, sealed cover, ensuring the windings are protected from moisture, dust, and mechanical wear during operation. The operator carefully inverts the stator and places it onto a conveyor belt, which then moves it to the next assembly station. At this stage, a PCB with a Hall sensor is precisely aligned and mounted onto the stator. The connecting wires are soldered securely to the PCB, ensuring reliable electrical connections. The Hall sensor plays a critical role in detecting the rotor’s position, enabling precise motor control. This step is vital for enhancing the motor's performance, ensuring accurate feedback, and optimizing efficiency during operation.

11. 15.Hall Sensor Assembly 16. Vision Inspection After soldering the PCB to the wires, the PCB is carefully inserted into the small slots created on the surface of the stator. A layer of paper is placed between the stator and the PCB to prevent direct contact and protect the components. Then, Dowsil adhesive is applied to securely bond the PCB, paper, and stator together. A cable tie is used to ensure the PCB is firmly held in place, ensuring stability and preventing movement during operation. Vision inspection of a completed stator on an assembly line uses high-resolution cameras and image processing software to ensure the stator meets quality standards. It checks for surface defects, dimensional accuracy, and proper assembly, such as correct winding alignment and secure components. The system also verifies part orientation, detects potential flaws like cracks or missing components, and ensures the stator meets design specifications. The process is automated for efficient, real-time quality control, improving consistency and reducing human error in the production process.

12. 17.Electrical Testing Electrical testing of a stator at the end of the assembly line is a critical step to ensure the component's safety, performance, and long-term reliability before it is integrated into the final product, such as a motor or an electric vehicle hub. These tests help identify potential defects early, such as insulation failures, poor connections, incorrect winding configurations, or other issues that could lead to operational failure. Conducting thorough electrical testing helps prevent costly repairs, warranty claims, and ensures compliance with safety standards. The types of electrical tests used for stators in the assembly line i nclude : HiPot Testing (High Potential Testing) Constant Resistance Testing 3.Inductance Testing 4.Surge Testing Together, these tests are essential for confirming that the stator is electrically safe, performs optimally, and will operate reliably in the final product. They help identify and eliminate defects early in the production process, reducing the likelihood of failures in the field and improving the overall quality of the end product.

13. 17A. HiPot Testing HiPot (High Potential) testing in stator assembly is a crucial step in the production flow to ensure the stator's insulation integrity and electrical safety. During this test, a high-voltage is applied between the stator windings and the stator core (ground) to check for potential breakdowns in insulation. The process flow of hipot testing is : Pre-Test Inspection: Before HiPot testing, the stator assembly is inspected for physical defects or visible signs of damage to the windings and insulation. Application of High Voltage: A high-voltage source is connected to the windings while the stator core is grounded. The test voltage is significantly higher than the stator's operating voltage, ensuring the insulation can withstand extreme conditions. Monitoring: During the test, any electrical leakage or breakdowns in insulation are monitored. If the stator fails to maintain the high-voltage without leakage, it indicates faulty insulation, which could lead to failures in the motor. Test Completion: If the stator passes the test, it confirms the insulation integrity, allowing it to proceed to further testing or assembly stages. If it fails, the stator is either repaired or discarded. Post-Test Documentation: The results of the HiPot test are recorded for quality assurance and traceability purposes.

14. 17B. Constant Resistance Testing Constant Resistance Testing in the stator assembly flow ensures the integrity of the windings by detecting faults like shorts or open circuits. The process follows these steps: Pre-Test Setup: After winding assembly, the stator is prepared for resistance measurement. Measurement: A resistance measurement device is connected to the stator windings to monitor resistance values. Comparison: The measured resistance is compared to the stator’s specifications to check for any discrepancies. Fault Detection: If resistance is out of tolerance, potential issues like shorts or breaks are flagged. Corrective Action: Faulty stators are reworked or discarded, and only those passing the test proceed. Documentation: Results are recorded for quality assurance before the stator undergoes further testing. This ensures the stator’s electrical integrity before moving on to additional tests or assembly steps.

15. 17C. Inductance Testing Inductance testing of the stator in a hub wheel motor ensures the stator's windings generate the correct magnetic fields for efficient motor operation. Pre-Test Setup: The stator is connected to an inductance measurement device after assembly. Inductance Measurement: A low-frequency current is applied, and the inductance is measured. Comparison with Specifications: The measured value is compared to design specifications to verify correct winding configuration. Fault Detection: If inductance is out of range, it indicates issues like incorrect winding or poor connections. Corrective Action: Stators failing the test are reworked or discarded. Documentation: Results are recorded for quality assurance and traceability. This test ensures stators meet performance standards and function reliably in the motor.

16. 17D. Surge Testing Surge testing of the stator in a hub motor assembly ensures the stator can withstand high-voltage surges, which can occur during startup or electrical transients. Pre-Test Setup: The stator is connected to a surge testing device. Surge Application: High-voltage pulses are applied to simulate stress conditions. Monitoring: The stator is monitored for insulation breakdown or leakage. Fault Detection: Failures indicate weak insulation or winding issues. Corrective Action: Failed stators are reworked or discarded. Documentation: Results are recorded for quality assurance. This test ensures the stator can handle electrical stress and performs reliably in the motor.

17. 18. EOL Testing 19. Final Packing End-of-line (EOL) testing at the assembly line of a hub wheel stator involves verifying the functionality and quality of the stator after assembly. It includes checks for electrical performance, insulation integrity, and mechanical alignment. The test ensures that the stator meets required specifications before it proceeds to the next production stage. Common tests include voltage, current, and resistance measurements. Successful EOL testing confirms that the stator is fully operational and ready for integration into the hub wheel system. The final cable tie and insulation process for the stator secures the windings in place and protects them from electrical leakage. Cable ties are used to keep the windings stable, while insulation materials like resin or varnish are applied to prevent shorts and environmental damage. The stator is then cured to harden the insulation, ensuring durability. Finally, a thorough inspection ensures proper sealing and safety of the assembly.

18. ROTOR MANUFACTURING PROCESS FLOW

19. 1.Traceability Marking 2. Rim ID Check up Traceability marking involves applying a unique identifier, such as a serial number or barcode, to each component of the rotor assembly. This ensures every part can be tracked throughout the manufacturing process, allowing for quality control and inventory management. In case of defects or issues, traceability markings help quickly locate the source of the problem. The system enhances transparency and accountability in production. It also supports warranty claims and repairs by providing detailed part history. Effective traceability reduces the risk of errors and increases overall production efficiency. The Rim ID check ensures that the rim component is correctly identified and conforms to the necessary specifications for the rotor assembly. The inspection process verifies the rim’s size, material, and quality, making sure it fits the design requirements of the motor system. This step prevents any mismatches or defects that could lead to operational failure later. The rim’s structural integrity is also checked for any signs of damage or flaws. The check-up helps prevent costly errors by catching issues early in the process. It ensures that only high-quality and properly identified rims proceed to the next stage

20. 3. Magnet Assy 4.Glue Curing Glue curing is the process where adhesive materials used to bond parts of the rotor are hardened using heat or chemical treatments. This ensures a strong, durable bond between the components, such as the magnets and rotor parts. The curing process is carefully controlled, as improper curing can weaken the bond, leading to potential mechanical failures. The glue’s curing time and temperature are optimized to guarantee the best adhesion without compromising the material integrity. Once fully cured, the components remain securely in place, preventing movement or misalignment. Magnet assembly involves the precise installation of 60 permanent magnets into the rotor, which are critical for generating the electromagnetic field that powers the motor. Loctite adhesive is used to secure the magnets in place, ensuring they remain fixed during operation and preventing any misalignment or detachment. The magnets are carefully aligned to maintain optimal performance and efficiency. Each magnet’s polarity and positioning are verified to meet the specific design requirements. The use of Loctite ensures a strong, durable bond that withstands operational stresses and temperature fluctuations.

21. 5. Anti - Corrosion Painting 6. Coating Curing Corrosion painting is a protective process where a specialized coating is applied to the rotor and rim components to guard against rust and environmental damage. This coating helps extend the lifespan of the motor by providing a barrier against moisture, dirt, and other corrosive elements. The application process requires precision to cover all exposed surfaces evenly and thoroughly. The paint used is designed to withstand harsh conditions, including temperature fluctuations and exposure to chemicals. This protective layer enhances the rotor's durability and maintains its performance over time. Coating curing involves applying heat or chemical treatment to hardened coatings, such as anti-corrosion or decorative layers, on rotor and rim components. The curing process solidifies and strengthens the coating, improving its adhesion to the surface. It ensures that the coating is resistant to wear, scratches, and environmental degradation, enhancing both the aesthetic and functional qualities of the rotor. The curing time and temperature are carefully controlled to achieve optimal hardness and durability. Once cured, the rotor components are ready for final inspection and assembly into the motor system.

22. HUB MOTOR FINAL ASSEMBLY

23. 1. Rotor Loading 2. Sealant Apply The rotor is carefully positioned inside a machine, ensuring proper alignment. The rotor’s positioning is crucial for the motor's performance, enabling smooth rotation. Special tools are used to handle the rotor to prevent damage. This process must be executed with precision to avoid imbalance. Correct rotor loading contributes to the overall efficiency and lifespan of the motor. A vision system is integrated into the machine which scans after positioning and detects if any mistakes in positioning of the rotor by the operator Sealant is applied to the loaded rotor to prevent moisture, dirt, and contaminants from entering. This helps in protecting the rotor from corrosion and other environmental factors. A machine is used for applying the sealant on the rotor ,once the loaded rotor comes to this step then a nozzle from the machine releases sealant thus ensures a tight fit and improves the motor’s durability. Application needs to be uniform and carefully controlled to avoid over-application.

24. 3. RH Cover Assembly 4. Pre – Torque @ RH Cover The right-hand cover is carefully aligned and fitted to the rotor, ensuring that it provides proper enclosure. This cover secures rotor from external damage. Fasteners are used to attach the cover securely to prevent vibrations. The RH cover must be tightly sealed to avoid any leakage. A proper assembly of this cover contributes to the motor's structural integrity. Before final torqueing , the right-hand cover is pre-torqued to a specified value, ensuring that all components are properly aligned. This temporary tightening helps maintain the cover's position as the motor progresses through assembly. It allows for adjustments, if necessary, before the final tightening. Pre-torquing also helps to prevent misalignment of components during subsequent steps. This ensures that no parts shift unexpectedly.

25. 5. Auto Torque @ RH Cover 6. Inverting An automated system is employed to apply precise torque to the right-hand cover, ensuring uniformity and accuracy in tightening. The automated torqueing process reduces human error and improves consistency across all motor assemblies. Proper torque is crucial for preventing issues like component displacement or vibrations. This step guarantees that the cover is tightly secured. Ensuring correct torque application is essential for the overall reliability of the motor. The rotor is inverted to facilitate the loading of stator on the opposite side of the motor. This positioning allows for easier access to internal parts for further assembly and testing. A machine is specifically assigned for inverting does the job of inverting the stator. It also helps in evenly distributing the components and ensuring alignment. Inverting the motor is necessary to prevent damage to sensitive parts during assembly.

26. 7. EOL Test of Stator 8. Stator Loading The stator undergoes an end-of-line (EOL) test to check for electrical continuity and insulation integrity. This test ensures that the stator is free from defects that could cause electrical failure. The EOL test checks the stator's functionality under conditions that simulate actual motor operation. Any issues detected during this test are flagged for correction. This step is crucial for verifying the stator’s quality before moving on to the next stages of assembly. The stator is carefully loaded into the motor casing, ensuring that it is properly aligned with the rotor. This step requires precision to ensure that the magnetic field interactions between the stator and rotor function effectively. Proper stator placement ensures that the motor performs efficiently and smoothly. The stator must be securely seated to prevent any misalignment during the motor’s operation. Stator loading is key to achieving the desired motor performance.

27. 9.Sealant Apply @ LH 10. LH Cover Loading Sealant is applied to the left-hand side (LH) of the motor to protect the motor's components from environmental factors. The sealant forms a protective barrier against moisture and dust, which could damage the motor’s internal parts. Careful application is essential to ensure that no excess sealant interferes with the motor’s function. The sealant must be evenly distributed to ensure proper sealing. This step helps extend the motor's lifespan and prevent failures due to contamination. The left-hand cover is placed and aligned onto the motor casing, securing the stator and rotor inside. This cover serves to enclose the motor and protect its internal components from external damage. The cover must fit snugly to ensure no gaps that could allow contamination. Once positioned, the cover is fastened using bolts or screws. Proper alignment and sealing of the LH cover are critical to maintaining motor integrity and performance.

28. 11. Dust Cover Assembly 12. Motor Unloading The dust cover is assembled to shield the motor’s internals from dust and debris. This cover ensures that external particles do not enter the motor and interfere with its performance. It is essential for maintaining the motor's cleanliness and operational longevity. The dust cover is securely fitted to prevent it from being dislodged during motor use. This step adds an additional layer of protection to the motor’s internal components. Once fully assembled, the motor is carefully unloaded from the production line for further inspection or testing. This step ensures that the motor is complete and free of any assembly defects. During unloading, all components are checked to confirm they are correctly installed. The motor is then moved to the testing area or prepared for packaging. Proper unloading is necessary to avoid damaging the motor after the assembly process.

29. 13.Performance Testing 14. Noise Testing The motor undergoes a series of tests to ensure it meets the required performance specifications. These tests check the motor’s speed, torque, and efficiency under different conditions. Performance testing helps identify any deviations from the expected operation. Any motor that fails to meet these standards is flagged for further inspection. This step is critical for ensuring the motor will function properly in its intended application. Noise testing is performed to ensure that the motor operates within acceptable sound levels. Excessive noise can be a sign of mechanical issues or inefficiencies. The motor is tested at various speeds and loads to assess its acoustic output. The testing also helps detect vibrations that could affect performance. Ensuring low noise levels is vital for meeting customer expectations and regulatory requirements.

30. 15. Hi-pot Testing 16. Sealant Apply High-potential ( hipot ) testing is performed to verify the electrical insulation integrity of the motor. A high-voltage test is applied to detect any potential electrical leaks or breakdowns in insulation. This step helps ensure the motor is safe for use and complies with electrical safety standards. Proper insulation prevents electrical shorts and ensures the motor’s long-term reliability. The hipot test is a critical safety check before final motor approval. Another layer of sealant is applied to ensure that the motor is fully protected from contaminants. This final sealant layer is applied to areas where additional protection is needed. It ensures the motor’s housing remains airtight and resistant to moisture. Careful and consistent application is vital to avoid over-sealing, which could hinder motor function. This step improves the overall durability and environmental protection of the motor.

31. 17. Dry Leak Testing 18. Cable Guide Assembly The motor undergoes dry leak testing to check for air leaks or cracks in the housing. This ensures that the motor is completely sealed, preventing the ingress of dirt or moisture. The motor is pressurized, and any leaks are detected and addressed immediately. Leak testing ensures that the motor meets quality control standards before being shipped. This step is crucial for ensuring that the motor remains functional and protected. The cable guide is installed to organize and secure the motor’s wiring and prevent damage during operation. Proper cable routing helps to avoid interference with the motor’s moving parts. The guide ensures that cables are not exposed to wear and tear, extending their life. It also helps in maintaining a neat and efficient assembly. Proper cable management ensures the motor's electrical components operate safely and without obstruction.

32. 19. Visual Inspection and Packing A thorough visual inspection is conducted to check for any visible defects or errors in the motor’s assembly. Any issues discovered during this inspection are addressed before the motor is packed. The motor is cleaned and prepared for shipment, ensuring it is free from dust or contaminants. It is then carefully packed to prevent any damage during transit. This final check ensures the motor arrives in perfect condition and is ready for customer use.