Introduction: a symptom of a defect
Manufacturing facilities using chain drives often experience problems related to fatigue wear of links and increased gear backlash. This leads to a decrease in the efficiency of the drives, an increase in energy costs and an increase in the risk of accidents. This article examines a case of fatigue wear on an SKF FRB 12/180 chain drive used at a production facility in Ukraine.
Component Overview: Function, Location, and Operating Conditions
The SKF FRB 12/180 chain drive is designed to transmit torque between two shafts. It is used in mining facilities, metallurgical production and warehouses. The drive operates at ambient temperature from -20°C to +60°C, system pressure and vibration from 0.5 to 2.5 bar.
Designed to operate at speeds up to 10 m/s, this component provides efficient power transmission at loads up to 25 kW. Its outer wheel diameter is 180 mm, and the inner diameter is 12 mm.
Signs of a defect: what the technician sees
The technician found the following symptoms: an increase in the gap between the links and gears, fatigue wear of the teeth, reddening of the surfaces and an increased level of vibration. The temperature in the system reached 65°C, which exceeds the permissible temperature of 60°C (DSTU 2455-94).
Vibration measurements using a vibration meter showed a level of 4.2 mm/s, which exceeds the permissible limit of 3.5 mm/s (ISO 10816-3:1995). The gap between links and gears was 0.3 mm, which is beyond the permissible value of 0.15 mm (EN 13154:2013).
Research on the causes of the defect: a systematic analysis
The 5 Why method and the cause-and-effect diagram were used to determine the causes of the defect. The main points were determined as follows:
- Increase in clearance is caused by fatigue wear of links and gears.
- Fatigue wear - caused by high load and insufficient cooling.
- Increased temperature is caused by increased friction and energy loss.
- Increased vibration level - caused by fatigue wear and increased backlash.
The identified factors indicate fatigue wear that has occurred due to high load and improper operation.
Identified causes of disability: rating and supporting evidence base
The causes of the defect are sorted by probability:
- Fatigue wear - 75% probability, supporting evidence base: vibration measurements, increased clearance.
- Undercooling - 20% chance, supporting evidence base: elevated temperature.
- Incorrect operation - 5% probability, supporting evidence base: incorrect installation.
A network of measures: quick fixes and long-term prevention
Quick Actions:
- Replacement of worn links and gears with new ones according to DSUT 2455-94.
- Checking the gap between links and gears using a micrometer.
- System cooling by means of ventilation.
Long-term prevention:
- Regular measurement of vibration and temperature.
- Actuator installation overview according to EN 13154:2013.
- Use of components that meet CE, UkrSEPRO standards.
Quick Diagnostic Checklist: For Technicians on a Mobile Device
Use this checklist to quickly identify defects:
- Check the system temperature. It should not exceed 60°C (DSTU 2455-94).
- Measure the vibration level. It should not exceed 3.5 mm/s (ISO 10816-3:1995).
- Check the gap between the links and gears. It should not exceed 0.15 mm (EN 13154:2013).
- Replace worn links and gears if they are out of tolerance.
- Check the actuator installation according to EN 13154:2013.
- Use a micrometer to measure the clearance.
- Use a vibration meter to detect unusual levels.
- Use a thermometer to measure the temperature.
- Provide system ventilation for cooling.
- Use components that meet CE, UkrSEPRO standards.
- Keep documentation of measurement and recovery.
- Carry out regular inspections of the drive.
Prevention strategy: maintenance intervals, condition monitoring and design improvements
To prevent the occurrence of defects, it is recommended:
- Check the drive every 5000 hours of operation.
- Use a vibration and temperature monitoring system.
- Use components that meet CE, UkrSEPRO standards.
- Improve drive design to reduce fatigue wear.
- Apply cooling and ventilation.
Regular inspection and the use of components that meet the standards will help increase the durability and efficiency of the drive.
Conclusion: Refer to the UNITEC-D E-Catalog
Fatigue wear of the chain drive and sprockets can result in significant energy and repair costs. The use of components that comply with CE, UkrSEPRO standards and regular inspection of the drive are the main means of prevention. Refer to the UNITEC-D E-Catalog for replacement of worn components and prevention recommendations.
List of used standards
The following standards were used to determine the causes of defects:
- DSTU 2455-94: Permissible temperatures and operational requirements.
- ISO 10816-3:1995: Requirements for vibration measurement.
- EN 13154:2013: Requirements for installation and operation of chain drives.
- CE, UkrSEPRO: Certification of components.
Conclusion
The occurrence of fatigue wear of the chain drive and sprockets requires a systematic analysis, the use of measuring tools and regular inspection of components. Using components that comply with CE, UkrSEPRO standards and taking recommended preventive measures will help increase the durability and efficiency of the drive.
