Smith & Nephew Orthopedics Reduces Unplanned Downtime by 90% With Help from IR.

Allan Warren Smith & Nephew Orthopedics

ABSTRACT

In early 2006 Smith & Nephew Orthopedics started a predictive maintenance program utilizing infrared, vibration, motor circuit analysis and ultrasonic testing. We began with 67 monthly, 20 quarterly, and 670 annual inspections. Along with checking for electrical issues we have utilized infrared to diagnosis a number of potential failures on machine bearings. In just one year, we reduced unplanned downtime and emergency work orders by 90%, and are planning to expand the program. Currently we have eight level II thermographers, and two with level III certification.

INTRODUCTION

Developing the predictive program has been both challenging and rewarding. Among the challenges: Identifying critical equipment, frequency of testing, when to take action, which technologies to use, routes, parameters, support, and how to handle the increased workload of a new PdM program.

The impact of application of new PdM technologies can create some misleading initial results. Problems that have been "lived with" may now be subject to recommendations from PdM specialists in early phases of technology introduction on an asset. An increase in work requests causes an increase in maintenance cost due to purchase of replacement parts, consumables and perhaps some outside services.

“Make sure PdM program sponsors and managers understand that cost may go up before they come down”. A tip excerpted from "Predictive Maintenance Management" Course workbook by Jack Nicholas Jr. Among the rewards; reduced downtime, reduced emergency work orders, training and utilizing new technologies.

Our program found many problems that had been “lived with” as we implemented the PdM program. With management support we were able to move forward despite objections from unlikely sources. Of the lived with issues, seven air compressor contactors were identified as having internal problems; this was determined by infrared and voltage drop testing. A comment made to me was “we have never had to rebuild contactors in the past”. The answer was obvious; we did not know we had a problem in the past.

Case study two discusses one of our contactor problems where the insulation of the incoming cables was 253 degrees Fahrenheit at 45 percent load. One quickly realizes the benefit of infrared in finding unknown problems. Had the contactor failed, we had the possibility of fire, motor damage, and potentially having several machines down. We utilize three compressors in this building, however, one being down can have a significant impact on production.

CASE STUDY-1: DUST COLLECTOR BEARINGS

Figures 1 and 2 show fan shaft bearings on a dust collector that self destructed on a Sunday just hours before the monthly scheduled vibration testing, we added infrared scans to all our dust collectors after this incident. The vibration analysis from the previous month did not indicate a problem.

Figure 1. Fan shaft bearing Figure 2. Fan shaft bearing

Production was not scheduled; however the PdM technician was onsite doing inspections when this was discovered. Four people were called in to assist in replacing the bearings, as figure 1 indicates both bearings were welded to the shaft thus complicating repair. Twelve hours later the unit was restarted.

Infrared along with vibration have indicated problems with four other dust collectors before catastrophic failure occurred, and we were able to schedule the bearing replacements with no lost production.

Figures 3 and 4 indicate a fan shaft running hot, this was confirmed with vibration analysis. The working conditions that day were 58 degrees Fahrenheit with 15 to 20 knot winds which had a considerable cooling effect. Figure 4 shows the outer bearing at a much higher temperature as would be expected with an overhung rotor. The emissivity was at 0.95 due to a very dull paint surface at a distance of 3 feet.

Figure 3. Fan shaft bearing Figure 4. Outboard fan shaft bearing

CASE STUDY-2: AIR COMPRESSOR CONTACTORS

Figures 5 and 6 are of an air compressor contactor with internal problems, the incoming cables were up to 253 degrees Fahrenheit, the compressor was shut down until repairs were completed. After repairs temperatures were in the 111 to 127 Fahrenheit range which is normal operating temperatures.

Figure 5. Air compressor contactor with internal problems

Figure 6. Air compressor contactor

Figures 7 and 8 indicate normal operating temperatures after repair.

Figure 7. Contactor after repair

Figure 8. Contactor after repair

CASE STUDY-3: AIR COMPRESSOR MOTOR COUPLING

Figure 9 is a motor coupling on a 150 horsepower rotary screw air compressor, when the coupling was disassembled the rubber inserts were badly worn. Figure 10 is a visual and figure 11 is the infrared image after repair.

Figure 9. Motor coupling on a 150 horsepower rotary screw air compressor

Figure 10.Visible image after repair Figure 11. IR image after repair

And finally a word about safety; the contactor in Figure 12 was found when the cabinet was opened for the monthly infrared inspection. A motor circuit test revealed damage to the motor windings when the contactor shorted. Be sure to follow safety policies and wear your PPE.

SUMMARY

Smith & Nephew has quickly realized the benefits of a PdM program and what an important role infrared has in locating potential problems. Smith & Nephew’s vision is to be the best at helping people regain their lives by repairing and healing the human body. Reliability is essential to our success and infrared makes a major contribution.

REFERENCES

Jack Nicholas Jr. www.masteringmaintenance.com www.Reliabilityweb.com

ACKNOWLEDGEMENTS

The authors wish to thank the Infrared Training Center at FLIR Systems and Smith & Nephew for providing the resources to make this work possible.

ABOUT THE AUTHOR

Allan has 20 years experience in machine repair focusing on electrical and machine automation. Within that twenty years four years as a maintenance supervisor, and three years in charge of predictive maintenance. Allan holds a level III ITC infrared certification, advanced motor circuit analysis, and level II vibration training.