Common Fault Diagnosis and Troubleshooting of Ball Screw Actuators

Although ball screw actuators have advantages such as high efficiency, high precision, and long life, they may still fail due to various factors during long-term operation, affecting equipment performance or even causing downtime. This article will systematically classify the common types of failures of ball screw actuators, analyze their causes, and provide corresponding troubleshooting and solutions to help maintenance personnel and engineers quickly locate problems and ensure stable operation of equipment.

1. Common Types of Failures and Diagnosis

Typical failures of ball screw actuators can be divided into the following categories:

1.1 Abnormal Noise or Vibration

• Phenomenon

There are abnormal metal friction sounds, whistling sounds or vibrations during operation.
Intermittent "clicking" sounds or vibrations occur during movement.

• Possible causes

The ball screw lacks lubrication or the lubricant deteriorates and dries up.
The ball inside the ball nut is broken or stuck.
There are foreign objects (such as chips and dust) in the screw or guide rail.
The installation is not parallel or the coaxiality is poor, causing extrusion or eccentric loading.

• Solution

Check whether the lubrication system is normal and add or replace grease/oil.
Clean foreign matter on the screw guide rail.
Disassemble and inspect the ball nut to see if the ball assembly needs to be replaced.
Check the installation accuracy and realign the slide and drive device.

1.2 Large Repeat Positioning Error

• Phenomenon

The position deviation becomes larger when returning to the origin.
When the same instruction is run multiple times, the end position is inconsistent.

• Possible reasons

There is a gap or backlash between the screw and the nut.
The coupling between the motor and the screw is loose or has a gap.
The bearings at both ends of the screw are loose.
The encoder is not accurate enough or the connection is abnormal.

• Solution

Pre-tighten the nut and use double nuts to eliminate backlash.
Tighten the motor coupling and check for slippage.
Check whether the support seat and bearing are loose or worn.
Calibrate the encoder of the control system or replace the high-resolution encoder.

1.3 Limited Travel or Stuck

• Phenomenon

The slider cannot move to the set travel and stops early.
The screw is stuck and cannot rotate, or the slider is stuck.

• Possible causes

Foreign matter or debris is stuck in the lead screw or guide rail.
The lead screw is deformed or bent, resulting in obstructed travel.
The limit switch is set in the wrong position.
The internal ball falls off or the circulation path is damaged.

• Solution

Clean the lead screw and guide rail thoroughly to ensure that there are no impurities.
Use a dial gauge to check the straightness of the lead screw and replace the lead screw if necessary.
Calibrate the limit switch position or replace the failed switch.
Disassemble and inspect the internal structure of the nut. If the circulator is damaged, it needs to be replaced.

1.4 Overheating of the Lead Screw or Nut

• Phenomenon

The surface temperature of the lead screw rises significantly after running for a period of time.
The system has thermal expansion error or thermal protection alarm.

• Possible causes

Insufficient lubrication and increased rolling friction.
Improper lead selection and excessive load lead to increased drive power.
The running speed exceeds the design limit of the lead screw.
The preload of the ball nut is too large.

• Solution

Use an automatic lubrication system to ensure that the lubricant is supplied on time.
Check whether the screw is overloaded, adjust the running speed or replace the appropriate model.
Optimize the preload design to avoid unnecessary axial compression.

1.5 The Screw Does not Rotate Smoothly

• Phenomenon

The screw has a sense of fluctuation when idling or running at low speed.
The speed is uneven and the linear movement is discontinuous.

• Possible reasons

The screw pitch error is large or the processing is poor.
The bearing at the support end of the screw is worn or eccentric.
The coupling is installed eccentrically, causing periodic interference.

• Solution

Check the overall processing accuracy of the screw and consider replacing a high-precision model.
Replace or adjust the bearing group and recalibrate the installation.
Use a flexible coupling to absorb installation errors.

1.6 The Motor is Overloaded or Out of Step During Operation

• Phenomenon

Alarms, abnormal temperatures or out of step occur during motor operation.
The load movement speed is significantly slowed down.

• Possible reasons

The screw load is too large or the friction is abnormal.
The motor drive parameters do not match.
The screw is damaged or stuck inside, and the resistance is too large.

• Solution

Reduce the load or improve the guide system (such as checking the rail resistance).
Adjust the motor drive parameters (current, acceleration, speed, etc.).
Disassemble and repair the screw and nut, and replace parts if necessary.

2. Fault Prevention and Maintenance Suggestions

To avoid the occurrence of the above faults, daily inspection and preventive maintenance should be strengthened. Here are some suggestions:

2.1 Regular Lubrication

Add or replace grease or lubricating oil regularly according to the frequency of use and environmental conditions.
Automatic lubrication device is recommended for high-speed operation environment.

2.2 Cleaning and Maintenance

Keep the screw and guide area clean to prevent dust and chips from entering the raceway.
Check whether the sealing device (dust cover, scraper) is complete.

2.3 Tightening Inspection

Regularly check whether the bolts, couplings, support seats, etc. are loose.
Ensure that the drive shaft between the motor and the screw is installed coaxially.

2.4 Operation Monitoring

Monitor the operating status of the actuator through current monitoring, temperature sensor, encoder feedback, etc.
Cooperate with the motion control system to set reasonable limit, soft start and soft stop control.

Summary

Although the structure of the ball screw actuator is relatively simple, its operating stability has a key impact on the overall equipment performance. Through a detailed analysis of the fault type, we can perform daily inspections and maintenance more targetedly, reduce unplanned downtime, and improve production efficiency.