The automotive steering motor is the heart of the Electric Power Steering (EPS) system. It directly determines the steering feel, driving comfort, and vehicle safety.

 

The assembly of an automotive steering motor involves five critical stations:

 

1. Stator Core Insertion into Housing:

The stator core is pressed into the housing with slot insulation processing. The key controls are press-fit force and concentricity accuracy.

 

2. Rotor Magnet Assembly:

This process includes magnet magnetization, polarity identification, and press fitting. Assembly accuracy is required at the 0.02 mm level.

 

3. Stator Winding (Including Wire Stripping):

Enamel wire is wound into stator coils, followed by terminal wire stripping. The combined control of wire tension, winding arrangement, enamel stripping, and wire damage prevention has the greatest impact on production yield.

 

4. Terminal Welding:

The winding leads are welded to the terminals. Welding energy control and weld consistency determine the reliability of electrical connections.

 

5. Final Assembly and EOL Testing:

The stator and rotor are assembled, followed by inter-turn short circuit testing, withstand voltage testing, and performance testing to detect defective products before shipment.

 

The first two stations may appear highly precise, while the fourth and fifth stations seem more critical. However, the primary cause of product defects often comes from the third station: stator winding.

 

Why does stator winding have the greatest impact?

 

1. Enamel wire damage and insulation layer defects are difficult to detect visually.

Even minor damage to the enamel coating may create hidden quality risks that cannot be identified through visual inspection alone.

 

2. The process parameters are highly interconnected.

Wire tension, winding speed, wire arrangement logic, and stripping depth are closely linked. A slight adjustment to one parameter can affect the entire winding process.

 

3. Product changeovers require repeated parameter optimization.

EPS motors are no longer designed for a single vehicle application. As vehicle model lifecycles have shortened from around five years to two or three years, small-batch and multi-model production has become the new normal.

 

4. The impact is amplified throughout the production line.

As an upstream process, stator winding directly affects downstream assembly quality. Insufficient enamel stripping can lead to poor welding connections; uneven wire arrangement can impact heat dissipation and electrical performance; hidden wire damage may result in inter-turn short circuits or even motor failure.

 

 

4 Common Defects in the Winding Process and Solutions

 

Tension Fluctuation

Symptoms: Uneven coil tightness, collapsed winding layers, and wire breakage.

 

Solution: During high-speed winding, changes in spool diameter can amplify tension differences. Only a servo tensioner with real-time closed-loop adjustment can ensure consistent tightness of every winding turn.

 

Enamel Stripping Deviation

Symptoms: Incomplete stripping, excessive stripping, and wrinkled wire ends.

Consequences: Poor welding quality and conductor damage.

 

Solution: Insufficient enamel stripping results in weak welds, while excessive stripping damages the conductor. The stripping length and depth must be precisely set according to product requirements, and the stripping blade should be replaced when necessary.

 

Uneven Wire Arrangement

Symptoms: Overlapping wires, skipped winding, and uneven winding patterns.

Consequences: Uneven slot fill rate, poor heat dissipation, and potential risks of inter-turn short circuits.

 

Solution: Wire arrangement accuracy directly determines slot fill rate and heat dissipation performance, which is the basic capability of a winding machine.

 

Enamel Wire Damage

Symptoms: Exposed copper, wrinkled insulation layer, and reduced wire diameter.

Consequences: Inter-turn short circuits and potential motor burnout.

 

A stable winding process is the foundation of a stable production line. The winding equipment behind steering motors and complete EPS motor automated assembly line solutions is exactly where HONEST Automation has been deeply focused for nearly 20 years.

 

As a supplier of intelligent motor manufacturing equipment and automation solutions, HONEST Automation provides advanced winding solutions featuring closed-loop tension control, high-precision wire arrangement, wire protection structures, and one-click changeover for flexible production. We also offer a complete service process including sample trial production, on-site production support, and lifetime equipment upgrades, helping customers transform the winding process from the primary source of defects into the first line of quality control.

 

If you are facing challenges related to winding yield, production stability, or changeover efficiency for steering motors or other motor applications, feel free to contact us for a professional production line evaluation and technical recommendations from our engineers.