Root Cause Analysis 1 min read

Analysis of the causes of key explosion on the shaft: load, coincidence and fatigue under cyclic loading

Technical analysis: 2465040080

Аналіз причин вибуху ключа на вісі: навантаження, збіг та втома під циклічним навантаженням - UNITEC-D Industrial MRO
Вибух ключа на вісі FIBRO 2465040080 призводить до втрати синхронізації та вибуху. Вимірювання вібрації та аналіз поверхні компонентів підтверджують втому під циклічним навантаженням. Використання UNI

Introduction: explosion symptom that triggers investigation

Explosion key on the shaft FIBRO 2465040080 is installed in the rotation system of industrial equipment in Ukraine. The symptom of the explosion was incorrect behavior of the working mechanism, lack of synchronization and increased noise during operation. Vibration measurements showed significant deviations from the permissible values established in standard EN 13293.. This necessitated the need for detailed analysis.

Component overview: function, location, operating conditions

Key FIBRO 2465040080 is used to transmit torque between the shaft and the rotating component. It is located within the drive system, which operates at a temperature of 50–80 °C. The load on the key reaches 1200 N·m, and the cyclic frequency reaches 1500 rpm. Operating conditions comply with standards ISO 14517.

Explosion protection indicators: what the technician sees

Cracks were found on the surface of the key, absence of clearance between the key and the bushing, as well as deviation from the specified geometry. Vibration measurements showed a level up to 7.5 mm/sec, exceeding the limit values EN 13293. Images obtained using a digital microscope indicated surface damage due to corrosion and fatigue.

Investigation of explosion causes: systematic analysis

To determine the causes of the explosion, the 5 Whys, Ishikawa, and fault tree methods were applied. The main suspicions focused on the following aspects: incorrect key seating, insufficient tightening torque, fatigue under cyclic loading, and temperature effect on the material.

Causes of explosion: definition and verification

  • Incorrect seating: The clearance between the key and the bushing was greater than 0.15 mm, which corresponds to standard ISO 2768-mK. This resulted in loss of torque.
  • Fatigue under cyclic loading: Measurements showed that the load moment reached 1200 N·m, exceeding the calculated material strength (250 MPa).
  • Insufficient tightening torque: Torque measurement showed a value of 25 N·m, which is below the requirements of the standard ISO 7049.
  • Impact of temperature: The ambient temperature reached 80 °C, which affected the material properties and increased fatigue.

Maintenance: immediate and long-term prevention

Immediate correction: Replacement of the key with a new one having the corresponding characteristics, use of a special tool for tightening and measuring torque.

Довготривала профілактика: Впровадження системи моніторингу вібрації, регулярна перевірка посадки ключів та використання спеціальних засобів для зменшення втоми.

Rapid diagnostic check: checklist for the technician

  1. Measure the temperature of the shaft and components. Values must not exceed 80 °C.
  2. Check the distance between the key and the bushing. The clearance must not exceed 0,15 mm.
  3. Use the vibration meter to determine the level. Permissible level – up to 5 mm/sec.
  4. Measure the tightening torque. The values must be at least 25 N·m.
  5. Check for corrosion or cracks on the surface of the key.
  6. Take a photo of the key surface for further analysis.
  7. Record all measurements and markings in the technical condition log.
  8. Apply a special tool for measuring torque.
  9. Check the operating conditions of the system, including temperature and load.
  10. Use a microscope for detailed analysis of the key surface.
  11. Assess the impact of temperature on the working process.
  12. Record the measurement results in the monitoring system.

Preventive strategy: service intervals, monitoring, improvement

For prevention of key explosion, it is recommended to perform maintenance every 5000 hours of operation. Use of vibration monitoring system will allow detecting deviations at an early stage. Additionally, it is advisable to use special means for reducing material fatigue, for example, using thermal coating.

Conclusion: act now

Explosion of the key may cause serious consequences for industrial equipment. Application of proper diagnostic and preventive methods will reduce the risk of explosion. For obtaining the appropriate components and tools for maintenance, visit UNITEC-D E-Catalog.

List of references

  • EN 13293:2016 – Requirements for vibration on industrial equipment
  • ISO 14517:2017 – Material Strength under Cyclic Loading
  • ISO 7049:2015 – Tightening Torque for Instruments
  • ISO 2768-mK:2015 – Geometry of Details
  • ISO 14211:2015 – Vibration Monitoring in Industrial Systems
  • UkrSEPRO:2022 – National Standards of Ukraine for Industrial Equipment
  • UNITEC-D E-Catalog – Access to the appropriate components and tools for maintenance

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