Ceiling fan motors typically adopt a dual-bearing + central shaft structure, where the upper and lower bearings support the rotor shaft, and the stator features densely packed copper windings. During assembly, the stator housing press-fit and end-cap pressing can easily damage the enamelled wires. Therefore, the press-fit challenges extend beyond bearing installation and include stator housing press-fit, end-cap pressing, rotor shaft alignment, and verticality control.

Based on real mass-production data and factory experience, this article analyzes the typical press-fit problems in ceiling fan motor manufacturing and presents a complete solution using XIRO electric servo press machines.

Ceiling fan motors

（For confidentiality purposes, the product images shown are representative illustrations only and do not depict actual client-specific product）

1. Common Press-Fit Problems in Ceiling Fan Motor Assembly

Problem 1: Pressure fluctuation causes inconsistent interference fits

Typical failures

• Loose bearing (insufficient interference):

• Vibration value rises above 4.5 mm/s (ISO 10816), causing abnormal noise.

• Inner ring cracking (excessive interference):

• Bearing raceway stress exceeds the yield limit of GCr15 steel (~1800 MPa), generating debris that blocks the rotor.

Root causes

• Pneumatic system pressure fluctuation (±10%)

1. Compressor loading/unloading causes sudden flow drops

2. Long pipe length-to-diameter ratio increases pressure loss

3. Humidity variations affect air density and indirectly affect output force

• Hydraulic thermal drift (>5% force reduction)

        Summer oil temperature rise reduces viscosity, resulting in 5–8% output force decay.

Given that ceiling fan motors require only 8–20 μm interference for upper and lower bearings, even slight force instability leads to severe quality variation.

Problem 2: Poor position accuracy causes rotor eccentricity

Typical failures

• Rotor runout > 0.1 mm

• Noise level > 65 dB

• Periodic abnormal sound and structural resonance

• Long-term deterioration of motor performance and service life

Root causes

• Pneumatic cylinder repeatability only ±0.05 mm

In a long-shaft ceiling fan motor, accumulated guiding errors magnify directly into eccentricity.

• Mechanical stopper wear

After three months of continuous use, positioning deviation may increase by 200%.

Problem 3: Process instability leads to hidden damage

This is especially critical in ceiling fan motors because bearing defects occur during bearing press-fit, while enamelled wire damage mostly occurs during stator housing press-fit or end-cap pressing.

1. Hidden bearing damage

• Excessive speed → raceway indentation

• Angular misalignment → micro-cracks in inner ring

• Excessive interference → inner ring expansion failure

2. Stator enamelled wire damage (unique to ceiling fan motors)

Occurs mainly during stator housing press-fit or end-cap assembly:

• End-cap pressed in off-center, squeezing windings

• Uneven housing press-fit pressure → wire coating abrasion

• High-speed impact damages insulation

• Uncontrolled secondary contact point induces pressure shock

Consequences:

• Insulation drops from 100 MΩ to 1–10 MΩ

• Local overheating after 30–200 hours of operation

• Severe cases lead to short circuits or complete motor failure

3. Insufficient dwell time (<1 s) causes micro-fretting

Using GCr15 bearing steel (E ≈ 210 GPa) and standard steel housings:

• Typical interference fit 10–20 μm

• Contact stress 20–60 MPa

• Elastic compression of 1–4 μm occurs at the fit interface

• Without enough dwell time, 70%+ elastic deformation rebounds instantly, creating a 0.5–2 μm micro-gap

This micro-gap falls within the most dangerous range for fretting wear, directly reducing motor life.

4. Temperature influence

• Workshop temperature variation (±10°C) → bore size drift ±0.03 mm

• Summer hydraulic viscosity drop (>35°C) → 7%+ force attenuation

These lead to incline pressing and insufficient interference.

Problem 4: Manual intervention causes assembly inconsistency

Typical failures

• Rotor imbalance: amplitude > 0.15 mm

• Bearing lateral load → 50%+ life reduction

• Uneven air-gap → stator-rotor rubbing and coil burnout (34% of failures)

Root causes

• Manual alignment baseline

• Human visual deviation

• Early wear of locating pins (0.03–0.05 mm)

• Bearing tilt >0.5° cannot be visually detected (critical threshold: 0.3°)

2. XIRO Servo Press Machine Solutions for Ceiling Fan Motor Assembly

1. High-Precision Closed-Loop Control

XIRO servo press machines operate with a triple closed-loop system:

• Position loop: high-resolution encoder

• Force loop: strain-type force sensor

• Speed loop: vector current control for stable motion

This ensures precise press-fit of bearings, stator housings, and end caps.

Dynamic compensation

• PID compensation for thermal deformation

• Temperature drift compensation adjusts displacement based on material expansion

Multi-stage process programming (ceiling fan motor–specific)

Measured results

Ceiling Fan Motor Bearing Assembly Curve

 (Source: XIRO )

 2. Force–Displacement Curve Monitoring

Key functions

• Envelope comparison: Detects deviations against historical OK curves

• Fault-tree automatic analysis:

•       Peak force too high → undersized bore, poor lubrication

•       Curve jitter → misalignment

•       Abnormal slope → material hardness variation

•       Low plateau → insufficient interference

Results

3. Digital Quick-Change and Full Traceability

• HMI stores >100 process recipes

• Magnetic quick-change tooling (3 seconds)

• Each motor assigned a unique ID linked to its press-fit curve

• Fully compatible with MES / SPC systems

Efficiency comparison

Conclusion

XIRO electric servo press machines offer a complete, data-driven, and highly repeatable press-fit solution for ceiling fan motor production. By solving key issues such as interference instability, bearing tilt, rotor eccentricity, enamelled-wire damage, fretting wear, and manual assembly deviation, XIRO servo press machines significantly improve product quality and reduce defects.

With precise force control, position accuracy, force-displacement curve monitoring, and full digital traceability, XIRO enables ceiling fan motor manufacturers to achieve:

• Standardized assembly

• Reduced noise and vibration

• Improved reliability and motor life

• True digital manufacturing and quality traceability

XIRO electric servo press machines are not just a replacement for pneumatic or hydraulic press machines—they are the core equipment that enables standardized, scalable, and fully traceable ceiling fan motor production.