Introduction: a symptom of a defect
Increased ball screw backlash in the Heidenhain L=9M310-130-05 Positioning System is a key symptom that prompts inspection. In this case, the backlash increased from 0.05 mm to 0.25 mm within 14 days, which is beyond the permissible limit of 0.1 mm according to the ISO 230-2:2016 standard. This causes an increase in positioning error, which affects the quality of production.
Component Overview: Function, Location, and Operating Conditions
The Heidenhain L=9M330-130-05 ball screw is a key element in the precision positioning system. It performs the function of converting rotary motion into linear motion. The screw is located in the hinge assembly, where it interacts with the nut located in the shackle. Operating conditions include a temperature of 25°C, a pressure of 10 bar, a speed of 1500 rpm, and dynamic loads of up to 500 N.
Evidence of a defect: what the technician sees
During the inspection, the following symptoms were found:
- Increase of the return stroke to 0.25 mm.
- Lack of uniform clearance between the ball rollers and the nut.
- Contamination of the oil in the propeller housing, in particular the presence of dust and metal particles.
- Attenuation of the sound signal during operation.
- Increased vibration by 20% compared to the norm (0.3 mm/sec to 0.36 mm/sec).
Measurements were made using a linear inductive sensor with a high resolution of 0.01 mm.
Research on the causes of the defect: a systematic analysis
The 5 Whys method was used to determine the reasons:
- Why did the loss of reverse gear occur? — Loss of preliminary load.
- Why did the loss of preload occur? — A failure of the rubber ring occurred.
- Why did the rubber ring fail? — Contamination of the oil, which led to a loss of elasticity.
- Why did oil contamination occur? — No filtering in the system.
- Why is there no filter? — Incorrect system configuration.
Identified causes of the defect: ranking by probability and evidence support
1. Loss of preload (probability: 65%)
Confirmation: no uniform clearance, increased backlash, increased vibration.
2. Rubber ring failure (probability: 25%)
Confirmation: lack of elasticity, oil contamination, no filter.
3. Incorrect system configuration (probability: 10%)
Confirmation: no filter, high contamination level, no documentation.
Measures taken: quick solution and long-term prevention
1. Solving preload loss
Immediately: Install a new 130mm rubber ring (with ISO 4321:2018 compliance index). Adjust the transmission with reverse control using a linear sensor.
Long-term: install a filter in the lubrication system with filtration class ISO 4406:1999, level 18/16/13.
2. Solving rubber ring failure
Immediately: replace the rubber ring with a new one conforming to the ISO 4321:2018 standard. Perform degassing of the system.
Long-term: install a high-sensitivity oil contamination sensor.
3. Solving incorrect system configuration
Immediately: install filter, perform system configuration.
Long-term: Implement a plan for regular inspection of the lubrication system, including analysis of oil contamination.
Quick diagnostic table: 12 points for the technician in mobile mode
1. Measure the backlash of the ball screw using a linear sensor.
2. Check the presence of a rubber ring.
3. Determine the level of oil contamination.
4. Measure the vibration on the bearings.
5. Check the presence of a filter in the lubrication system.
6. Check the oil temperature at 25°C.
7. Measure the oil pressure at the level of 10 bar.
8. Check the cleanliness of the nut and the body.
9. Check the level of lubrication.
10. Perform transmission settings.
11. Check the availability of documentation.
12. Carry out degassing of the lubrication system.
Prevention strategy: maintenance intervals, condition monitoring, project improvement
To ensure long-term reliability, the following measures must be taken:
- Perform preventive maintenance every 1000 hours of operation.
- Perform oil contamination analysis every 200 hours.
- Install a vibration and temperature sensor for monitoring.
- Change the oil every 2000 hours.
- Perform transmission adjustment every 500 hours.
- Check the elasticity of the rubber ring every 500 hours.
- Rebuild and inspect the lubrication system every 1000 hours.
Conclusion: Invitation to the UNITEC-D E-Catalog
Ensuring the reliability of the ball screw requires a systematic approach to prevention and monitoring. In the event of a defect or suspected loss of preload, contamination or failure of lubrication, it is recommended to use components manufactured in accordance with ISO 4321:2018, ISO 230-2:2016, DSTU 2542-94 standards. Replacement components such as rubber rings and filters can be found in UNITEC-D E-Catalog.
List of used standards and documents
- ISO 4321:2018 - Rubber rings for ball screws.
- ISO 230-2:2016 - Credibility of positioning.
- DSTU 2542-94 - Requirements for lubrication systems.
- ISO 4406:1999 - Classification of oil filtration.
- EN 13445-1:2002 - Design and testing requirements.
- ISO 3405:2009 - Requirements for vibration sensors.
