Why a servomotor shaft can break?
A servomotor shaft can break due to a variety of mechanical, operational, or installation-related causes. Below are the most common reasons, categorized for clarity:
1. Mechanical Overload
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Excessive torque beyond design limits can shear the shaft.
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Sudden impact loads (e.g., emergency stops or collisions in CNC machines).
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Repeated shock loading or high-inertia starts/stops without proper ramping.
2. Misalignment
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Misalignment between the motor shaft and the driven load (e.g., gear, coupling, pulley) causes:
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Uneven stress distribution
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Shaft bending or fatigue over time
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Common in poor mounting or incorrect installation practices.
3. Fatigue Failure
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Cyclic stress over time, even if below yield strength, can cause crack initiation.
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Common in applications with frequent reversals or load fluctuations.
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Stress concentration points, such as keyways or sharp corners, accelerate fatigue.
4. Improper Coupling
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Using rigid couplings in applications needing flexible ones transmits undue stress to the shaft.
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Misuse of couplings that don’t accommodate slight misalignments or thermal expansion.
5. Sudden Stops or Faults in Drive System
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Servo drives that lack proper deceleration profiles or safety braking mechanisms may induce shock torque.
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Electrical faults causing uncontrolled motion or jamming can snap the shaft.
6. Poor Maintenance or Repair Practices
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Reassembled incorrectly (e.g., improper bearing preload or excessive shaft loading).
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Shaft damage during handling or bearing installation.
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