An electric vehicle motor stator assembly line is an automated production line used to manufacture motor stator assemblies. It is commonly used in the production of hairpin stators for electric vehicle traction motors. The line combines several operations, including slot insulation paper insertion, flat wire forming, conductor insertion, end-turn shaping and welding, to assemble the stator core and copper windings into a finished stator assembly.
In an electric motor, the stator is normally fixed inside the motor housing, while the rotor is mounted on the shaft and rotates inside the stator. When current flows through the stator windings, they generate a magnetic field that interacts with the rotor to produce rotation. The stator core provides the magnetic path and supports the windings.
Electric vehicle traction motors have demanding requirements for power density, efficiency and compact construction. Hairpin windings are one approach used to meet these requirements. Compared with conventional round-wire windings, flat wire windings have a different conductor arrangement and use of the available slot space. Their production requires dedicated forming, insertion and end-turn processing equipment.
Main Processes and Equipment in an EV Motor Stator Assembly Line
A typical hairpin stator production process includes slot insulation paper insertion, hairpin forming, conductor insertion, end-turn flaring, twisting, cutting and welding. Conveyors and locating fixtures connect the individual stations. The actual equipment layout depends on the stator slot count, winding layers and product design.
Automatic Slot Insulation Paper Insertion Machine
An automatic slot insulation paper insertion machine places insulating paper into the slots of the stator core. The paper provides electrical insulation between the windings and the core.
The machine typically performs paper unwinding, feeding, creasing, forming, cutting to length and insertion. The paper dimensions and insertion position must match the stator slot design to prevent misalignment, deformation or incomplete insertion.
Slot Paper Expansion and Inspection Machine
After paper insertion, some production lines use an expansion and inspection machine to shape the slot insulation paper and check its position or dimensions.
Depending on the process requirements, inspection may include paper height or insertion condition checks. Some automated lines also connect inspection results to a manufacturing execution system (MES) to record production data and equipment status. MES integration is a line-level configuration rather than a standard function of every paper expansion and inspection machine.
Flat Wire Processing and Hairpin Forming Machine
A hairpin forming machine processes the flat copper conductors used in the stator winding. Based on the product drawing and forming tooling, the machine feeds, straightens, strips the enamel coating and bends the copper wire into the required shape.
Depending on the winding design, the conductors may go through two-dimensional or three-dimensional forming. The finished hairpins are then arranged in the required order for the insertion process.
The forming operation must control conductor dimensions, bend positions and surface condition. Excessive deformation or damage can affect conductor insertion and subsequent welding.
Hairpin Insertion Machine and Coil Carrier
The hairpin insertion machine places the formed conductors into the slots of the stator core according to the specified winding arrangement.
Some production lines use a coil carrier or fixture, commonly referred to as a "nest," to arrange and position multiple hairpins before insertion. The equipment aligns the carrier with the stator core and uses positioning, lifting, clamping and insertion mechanisms to guide the conductors into the slots.
The carrier is a tooling component used to organize and locate the conductors. It is not part of the stator itself.
Stator Hairpin Flaring Machine
After the hairpins have been inserted into the stator core, their exposed ends need further shaping. The flaring machine adjusts the spacing, direction and circumferential arrangement of the conductor ends according to the winding design.
This operation prepares the hairpins for subsequent twisting and welding. The tooling must match the number of conductors, winding layers and end-turn configuration.
Hairpin flaring is different from slot paper expansion. The former shapes the copper conductor ends, while the latter processes the insulation paper inside the stator slots.
Stator Hairpin Twisting Machine
The twisting machine processes the exposed hairpin ends after flaring. It twists and positions the conductors according to the winding connection layout so that the ends to be joined are placed in the required positions.
The twisting result affects the following cutting and welding operations. The locating fixtures and twisting tooling must therefore be configured for the specific stator design and conductor arrangement.
Stator Hairpin Cutting and Leveling Machine
After twisting, the cutting and leveling machine trims the exposed copper ends to the specified length and prepares the end faces for welding.
Cutting length, end-face condition and conductor position must meet the requirements of the welding process. Depending on the production process, additional end-face grinding or cleaning may be used to remove surface contamination from the welding area.
Hairpin Stator Laser Welding Machine
The laser welding machine joins the hairpin ends after twisting and cutting to establish the required electrical connections in the stator winding.
Locating fixtures hold the conductors in position while the laser follows the programmed welding path and process parameters. Depending on the equipment design and production requirements, the machine may also include welding-area cleaning, fume extraction or post-weld inspection.
Automation and Production Data Management
In addition to the main processing machines, an EV motor stator assembly line may include conveyor systems, transfer units, locating fixtures, robots, loading and unloading equipment, and an electrical control system.
For production traceability, the equipment controls can be connected to a manufacturing execution system (MES). The system can collect process data, equipment status and inspection results. The actual configuration depends on the production cycle, product range, quality requirements and the factory's information system.
An electric vehicle motor stator assembly line is not simply a collection of individual machines. The equipment sequence, positioning methods and transfer operations must be coordinated with the stator structure and winding process. In hairpin stator production, conductor forming, insertion, flaring, twisting, cutting and welding are among the main operations requiring process control.
The manufacture and maintenance of stator assembly equipment also involve precision components such as locating blocks, mounting plates, fixtures, guide parts, connecting shafts and structural components. Hansheng Automation provides drawing-based custom CNC machining for precision components used in automation equipment and industrial machinery. Parts can be manufactured from aluminum alloys, steel and other specified materials.
