February 09, 2005
Airborne Ultrasonic Tip
Hydraulic Cylinder Leaks – Leaks inside rams are often the result of contaminated hydraulic fluid. Particles lodge themselves between the wiper and the cylinder wall eventually causing the seal to fail and the cylinder no longer holds its pressure. Ultrasound inspectors are trained to pinpoint these internal leaks using either contact stinger probes or magnetic sensors. Under pressure, a good cylinder should be quiet while in a leaking cylinder hydraulic fluid will pass the seal at the point of the breach creating gurgling, popping, or swishing sounds. Adjust the sensitivity of the detector to the highest level possible and position the magnetic sensor or contact probe in the approximate area of the ram’s wiper. Be sure to listen on all sides of the cylinder to ensure nothing is missed. Identifying hydraulic leaks ultrasonically can save several hours of labor by directing the repair to the correct area quickly.
Tip provided by SDT North America
Toll free: 1-800-667-5325
Tel: 905-349-2020
February 09, 2005
Reliability Centered Maintenance (RCM) Improves Safety and Reliability
“That’s the way we have always done it!” is a common refrain when asked why a great deal of maintenance work is done the way it is.
With RCM you will practice a detailed process that will ensure you are doing the right work to increase reliability and safety. Most of the time you will find that a maintenance program based on Reliability Centered Maintenance will actually reduce cost and increase availability over time as well.
Take three days to immerse yourself and your team in the world of Reliability Centered Maintenance with 12 Real World RCM Case Studies, a Reliability Incident Management Short Course and the new RCM Scorecard Workshop. The Reliability Centered Maintenance Managers’ Forum will jumpstart your journey to an improved maintenance program.
Please join us on March 9-11 at the Sheraton Sand Key resort in beautiful Clearwater Beach Florida. Register before February 11 to take advantage of great hotel discounts. Call 239-985-0317 to register for The Reliability Centered Maintenance Managers’ Forum or…
Register for the Reliability Centered Maintenance Managers’ Forum online
February 09, 2005
Motor Testing Tips
Motors powered by PWM drives can develop “pinhole” shorts in the windings. These faults will cause the drive to trip and can often be a challenge to detect and confirm. For example, conventional measurements of winding resistance using a digital multimeter and insulation to ground resistance using a meg-ohm meter will give acceptable readings. When the drive is put in bypass mode the motor will often operate on line power. As a result the fault is often mistakenly diagnosed as a drive problem.
Testing with Motor Circuit Analysis can detect these faults. They will appear as unbalanced measurements in either phase angle or current frequency response. Quickly and positively detecting or ruling out these faults can save hours in diagnostic time, and avoid the lost production time and costs associated with making a wrong call.
Tip provided by ALL-TEST Pro, A Division of BJM Corp http://www.alltestpro.com
Tel: 860.399.5937
February 09, 2005
Reliability Tip
Understand How Your Equipment Fails
We frequently hear folks say, “If only I knew the MTBF of my equipment I could set up a PM to repair or replace it before it breaks.” True, it is important to understand the frequency of your failures, but it is just as important to understand what type of failures you are having.
Failures fall into three basic categories; infant, random, and Wearout. Maintenance policies based on frequency alone have a high probability of failures. Why? Because a large portion of the equipment population fails in ways that make time based replacement or overhaul are counter productive.
Infant failures are caused by some quality issue related to spares quality, quality of maintenance, or quality of operation. Time based replacement or overhaul in this case will actually induce failures in the system.
Random failures occur at a constant frequency that is not related to time in service. Time based replacement or overhaul in this instance is ineffective at preventing the occurrence of failures. For random failures there is a 63% chance that a failure will occur before the MTBF.
Tip provided by Bill Keeter, CMRP
ARMS Reliability Engineers - USA, Inc.
Tel: 888-673-8360
http://www.armsus.com
Download a short presentation on Understanding Weibull Failure Characteristics
