Combining Hairpin Forming, Stator Stamping and Welding Expertise to Streamline Electric Motor Production

Electric motor design continues to evolve as manufacturers work toward smaller, lighter, and more powerful machines. A key driver is the efficient use of copper, which is both heavy and expensive. One important innovation has been the move from traditional round-wire windings to pre-formed rectangular conductors known as hairpins. These hairpins—so named because of their shape—are inserted into the stator core, locked in place, and then joined at their ends through welding.

This shift in design has created new requirements for forming, inserting, and joining processes. Understanding these processes helps to illustrate how improvements in equipment design directly impact motor performance, efficiency, and manufacturability.

Forming Hairpins

To produce copper hairpins, manufacturers use specialized CNC bending and transfer systems. For example, the ES-1A 48-axis coil processing machine from AMADA PRESS SYSTEM, allows high-speed, high-precision production by combining multiple steps into one continuous process: feeding, straightening, peeling, cutting, bending, and pressing.

These machines support copper wires of different cross-sectional sizes and can manage multiple conductor types in a single setup through program-controlled changeovers. Its ability to perform advanced plane bending and three-dimensional forming gives engineers flexibility in designing compact, high-efficiency motor windings.

Stator Core Production

Another important area of innovation is the production of the stator core itself. Traditionally, stator cores were stamped as single pieces using very large presses. More recent approaches divide the core into three segments. This modular structure improves material yield, reduces the size of the press required, and simplifies the factory layout.

Compact, high-precision presses combined with automated feeders – like AMADA PRESS SYSTEM’s SDEW-i3 GORIKI high-rigidity, high-speed precision series of presses and the ALFAS-03ARZ high-speed, high-precision NC roll feeder – now enable efficient stator production while reducing auxiliary requirements such as pit construction, coil handling, and overall energy use. This method not only improves precision and consistency but also reduces total production cost. Watch the video here.

Welding Hairpins

Once hairpins are inserted into the stator stack, their ends must be welded together. The challenge is to create reliable joints without damaging insulation or introducing defects such as spatter that could lead to electrical shorts. Three joining methods are commonly applied, each with distinct advantages depending on production needs:

• Laser Welding – A non-contact method well suited to high-speed production. Vision systems are often integrated to ensure precise alignment, as joint accessibility and tooling design can present challenges. Frequently used equipment includes a laser (infrared fiber laser or blue diode laser), fiber delivery, and scanning head. When built into an integrated system, machine vision, process monitoring, and other accessories can be added.
• Micro TIG Welding – A lower-cost solution that is effective when hairpins are well aligned and spacing is limited. This process is often considered for lower-volume production or repair work. AMADA WELD TECH’s high-performance MAWA-300B pulsed micro TIG welding power supply is ideal for hairpin welding, especially for low volume production or repair.
• Resistance Brazing – A robust process that naturally pulls the conductors together during welding, compensating for small gaps or misalignments. It requires access to both sides of the hairpin, which can be more difficult in compact motor designs. Selecting the appropriate joining method depends on factors such as hairpin geometry, accessibility, production volume, and required throughput. AMADA WELD TECH’s IS-800CA mid-frequency inverter resistance weld control with air actuated F160-Z pincer weld head are considered the best equipment for hairpin welding, especially for electric vehicles. Smaller electric motors can use smaller power supplies with less current capacity.

For more information on technologies used for hairpin welding, read our related blog Electric Motor Hairpin Welding: Comparing 3 Joining Technologies.

Bringing It Together

The production of hairpin stators illustrates how forming, stamping, and welding technologies converge to support the next generation of electric motors. By integrating these processes – using solutions from AMADA PRESS SYSTEM and AMADA WELD TECH – manufacturers can achieve greater control over product quality, optimize efficiency, and reduce overall production complexity.