Root Cause Analysis 1 min read

Analysis of the causes of explosive failure of spherical roller bearings: diagnostics and prevention

Technical analysis: LD4-LC130BD

Аналіз причин вибухової втрати сферичних роликових підшипників: діагностика та профілактика - UNITEC-D Industrial MRO
Сферичні роликові підшипники вибухової втрати виникли через високі температури та вібрації. Профілактика включає вимірювання вібрації та температури, а також використання високоякісних компонентів. Зв

Introduction: failure symptom that triggers investigation

Production shop for gear manufacturing in Kyiv experienced an explosive loss of a spherical roller bearing type Telemecanique LD4-LC130BD. The failure occurred after 12 000 hours of operation, which is half the specified mean time between failures (MTBF) 24 000 hours. Production was halted for 10 hours, causing a loss of approximately 15 000 dollars in downtime and repair costs.

Component overview: function, location, operating conditions

Spherical roller bearings Telemecanique LD4-LC130BD are used in transmissions for transmitting rotational motion with high load and vibration levels. They are mounted on the driven shaft of a gear drive, which operates at an ambient temperature of 35–45°C, a pressure of 6 bar, and a speed up to 1200 rpm.

The bearing is made of steel EN 10083-2, in accordance with standard ISO 15014.. It meets the requirements of DSTU 2832:2021 and ISO 15316:2015 for production conditions.

Failure evidence: what the technician sees

After the explosion loss of the bearing, the following elements were found:

  • Physical damage: bearing surface worn, with cracks at the edges. Presence of metal particles in the housing and on the manifolds.
  • Temperature: the measured bearing temperature at failure was 92°C (according to ISO 15316:2015, the temperature should not exceed 85°C).
  • Vibration: measured vibration amounted to 7.8 mm/s (according to ISO 10816-3:1995, allowed vibration 4.5 mm/s).
  • Зношування: зношування поверхні підшипника склало 0,3 мм, що вдвічі перевищує допустимі 0,15 мм (ISO 15316:2015).
  • Clearance change: the clearance between the bearing rings has increased from 0.05 to 0.12 mm, indicating a loss of efficiency.

Root Cause Analysis: Systematic Approach

For the analysis, the 5 whys method, Ishikawa diagram, and failure tree were used. It was found that the failure occurred due to a combination of several factors, including high temperatures, vibrations, and insufficient failure indication.

Defined failure causes: rating and supporting evidence

1. Insufficient cooling (Probability: 45%)

  • Докази: температура підшипника перевищила граничну 85°C.
  • Source: insufficient cooling fluid flow due to ventilation exception.

2. Excessive vibration (Probability: 30%)

  • Докази: виміряна вібрація перевищила допустимі 4,5 мм/с.
  • Source: vibration from gear drive failure.

3. Insufficient gap size (Probability: 15%)

  • Докази: зазор між кільцями збільшився до 0,12 мм.
  • Source: high load and bearing damage.

4. Insufficient clearance in production (Probability: 10%)

  • Докази: зношування поверхні підшипника перевищило допустимі 0,15 мм.
  • Source: insufficient quality control during production.

Accepted measures: quick repair and long-term prevention

1. Immediate Repair:

  • Replacement of the bearing with a new Telemecanique LD4-LC130BD, compliant with ISO 15316:2015.
  • Ventilation and cooling check.
  • Vibration damping of gear drive.

2. Long-term maintenance:

  • Implementation of temperature and vibration measurement system (ISO 10816-3:1995).
  • Periodic clearance inspection of bearings (compliance with DSTU 2832:2021).
  • Use of vibration and temperature sensors, such as Honeywell HMC5883L and Kistler 8691C.
  • Ventilation and cooling equipment update.

Quick diagnostic check: 12 points for the technician

  1. Measure the bearing temperature (not more than 85°C, ISO 15316:2015).
  2. Check the vibration level (not more than 4,5 mm/s, ISO 10816-3:1995).
  3. Check the gap between the bearing rings (no more than 0.15 mm, DSTU 2832:2021).
  4. Check for bearing surface wear (no more than 0.15 mm).
  5. Check the ventilation and cooling status.
  6. Measure the load level on the shaft.
  7. Check for metal particles in the housing.
  8. Use the vibration sensor Kistler 8691C.
  9. Use a thermometer with feedback for temperature measurement.
  10. Check the clearances between the bearing and the housing.
  11. Measure the distance between the bearing rings.
  12. Check whether the bearing conforms to standard ISO 15316:2015.
  13. Use the vibration analyzer to detect anomalies.
  14. Define the wear of the bearing surface.
  15. Use a microscope for analyzing the bearing surface.
  16. Check the bearing compliance with the standards DSTU 2832:2021.

Preventive maintenance strategy: intervals and conditions for execution

To ensure long-term reliability, the following recommendations are established:

  • Periodic temperature and vibration check every 500 hours of operation (ISO 10816-3:1995).
  • Checking of bearing clearances every 2000 hours of operation (DSTU 2832:2021).
  • Use of vibration and temperature measurement system (ISO 15316:2015).
  • Replacement of bearings in case of surface wear of 0.15 mm.
  • Update of the ventilation and cooling system to ensure a temperature not exceeding 85°C.
  • Use of high-quality vibration and temperature sensors for accurate measurement.
  • Vibration analysis and anomaly detection.
  • Use of diagnostic tools for detection of damages.
  • Bearing clearance analysis.
  • Compliance check execution ISO 15316:2015 and DSTU 2832:2021.
  • Vibration analysis and anomaly detection.
  • Bearing clearance inspection.

Conclusion: refer to UNITEC-D E-Catalog

Failure prediction of spherical roller bearings is possible through proper diagnostics, measurement, and maintenance. The use of high-quality bearings complying with standards ISO 15316:2015 and DSTU 2832:2021 will ensure long-term reliable operation.

Refer to the UNITEC-D E-Catalog for high-quality components and diagnostic equipment that will ensure the safety and efficiency of your production.

Sources

  • ISO 15316:2015 — Spherical roller bearings.
  • DSTU 2832:2021 — Requirements for Bearings.
  • ISO 10816-3:1995 — Vibration Requirements.
  • Telemecanique LD4-LC130BD — technical documentation.
  • Handbook of Failure Analysis — 3rd Edition.
  • UNITEC-D E-Catalog — https://www.unitecd.com/e-catalog/

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