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God Bless America 09/11/2001
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As the mining industry continues to look for the 100% availability of equipment, some mining companies are looking for new technologies to help them achieve their goals. Vibration analysis has been used for years for industrial applications, but only in the last few years, with the MSHA approval of the SKF data logger has the technology migrated to underground longwall mining. Vibration analysis is an excellent predictive maintenance tool, and a proactive maintenance tool that can help design equipment to last longer. Also by the use of oil analysis in conjunction with vibration analysis a new security can be realized with load changing heavy equipment, that is utilized daily in the mining industry. I will try to update the readers of this newsletter with new information as we discover and solve machine maintenance problems. I will accomplish this with newsletters that pertain to real case histories, as the one that follows. CASE HISTORY #18. "KPL Bearing" by: Larry Massey During March of 1999, while performing a periodic inspection of a Longwall tail drive, we were informed that the gear case oil analysis had increased wear particles and dirt. This was an indication of a special case. I have expressed in many case studies my enthusiasm for enveloped Gs filtered readings, for early detection of bearing problems. In this situation I used HFD readings (5K to 60K Hz overall reading) to recommend action. I could not find a major problem with Velocity, Acceleration, or Enveloped Gs spectrums. The biggest clue to this problem was the use of the HFD reading. HFD readings are excellent for finding metal to metal contact and lack of lubrication. The spectrum below also shows the readings after the new reducer was installed.
With high wear metals and dirt present in the oil analysis we recommended that they should replace the reducer. Mine management was able to schedule the replacement of the unit during the weekend. When the unit was disassembled it was found that the cat seal on the output was worn causing dirt and water to inter the unit. The intermediate shaft bearing as shown below had one complete set of rollers on one side of the bearing with a groove cut in each roller. This is an important illustration that proves the need for all present tools (Velocity, Acceleration, Enveloped Gs and HFD readings) for an accurate recommendation to our customers.
In the next newsletter I will illustrate a different case study of vibration analysis, that detects a problem and verification of the problem when investigated. If you have any questions please contact us. Feed back is very important to us. |
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