Motor QC Guide: 7 Winding Defects and How to Prevent Them

Longjiang Automation Equipment Co., Ltd. · Brushless Motor Winding Machine Source Factory

Winding Defects: The Invisible Killer in Motor Factories

Industry data: approximately 40% of early motor failures are directly related to winding quality. How many of these 7 defects have you encountered?

1. Inter-turn Short Circuit

Symptom: Insulation breakdown between adjacent coils, burns on power-up.

Root cause: Excessive tension damaging enamel coating, cross-wire compression.

Solution: Dynamic tension control + layer-by-layer insulation testing.

2. Turn Count Deviation

Symptom: Wrong RPM if under-wound, won't fit if over-wound.

Root cause: Counter malfunction, operator error.

Solution: Dual redundant counters + automatic verification.

3. Uneven Layer Winding

Symptom: Crossed/overlapping wires causing localized heating.

Root cause: Excessive play in wire guide mechanism, uneven tension.

Solution: Servo-driven wire guide + closed-loop feedback.

4. Enamel Damage

Symptom: Surface scratches on wound enameled wire.

Root cause: Worn guide wheels, burrs on tooling.

Solution: Regular component replacement + ceramic-coated guide wheels.

5. Tension Fluctuation

Symptom: Large resistance variance within same batch.

Root cause: Aging mechanical tensioners.

Solution: Upgrade to electronic closed-loop tension system.

6. Loose End Turns

Symptom: Loose, sagging wire at stator ends.

Root cause: Poor winding form design.

Solution: 3D-modeled winding forms + shaping process.

7. Low Slot Fill Factor

Symptom: Under-utilized slot space, low power density.

Root cause: Insufficient equipment precision — forced to wind "loose."

Solution: High-precision winding machines (±0.01mm) + optimized winding strategy.

Longjiang's QC Solution

Our machines have built-in turn count verification, tension monitoring, and wire break detection. Trial winding includes a report covering turn count consistency, resistance deviation, and visual quality scoring. QC starts from the first machine. Contact: +86 18968693691.