August 18, 2005
Sensor Tip
Trouble Shooting Industrial Accelerometer Installations
Accelerometer based monitoring systems can be tested to verify proper installation and operation, ensure data integrity, and identify most problems. Troubleshooting techniques are simple and can be performed with most monitoring systems and data collectors or simple test equipment.
Bias Output Voltage
• If the BOV is within manufacturer limits the sensor is most likely operating properly.
• The time waveform and FFT spectrum will verify fault diagnosis or proper operation.
Truncated Time Waveform: Sensor Overload
• Flattened time waveforms indicate that clipping is causing the amplifier to overload (from severe pump cavitation, steam release, impacts from loose or reciprocating parts and even gearmesh).
• Reduce clipping with a higher power supply voltage, ensure that the BOV is centered between supply voltage and ground voltage.
• Sensor overload may also produce a ski-slope spectrum, indicating low frequency noise (washover distortion).
• Caused by the circuits used to integrate acceleration signals to velocity or displacement, and high amplitude vibration from other machines.
Mounting Resonance Spectrum
• Mounting resonance can give false indication of high frequency machinery faults.
• The problem is most evident when using probe tips and magnets. Mounting sensor on thin plates such as machine guards can lower the mounting resonance.
Line Frequency Harmonics in Spectrum
• Harmonics of AC line power frequency usually indicate interference from motors, power lines and other emissive equipment.
• Ensure that the sensor shield is grounded. Avoid running the cable along side high voltage power lines and only cross power lines at right angles.
For more information on Bias Output Voltage, read Wilcoxon’s Technical Note 14: “Troubleshooting Industrial Accelerometer Installations.” This Tech Note from Wilcoxon’s extensive online Knowledge Desk explains BOV, gives examples of sensor readings and the faults they indicate, and includes a Trouble shooting chart for sensors.
August 18, 2005
Maintenance Planner/Scheduler Tip
For projects, use your CMMS work order numbering system to create an intelligent numbering system to assist with control and management of the work. Open and assign the next work order in the system for the overhaul of, for example, the large frame-milling machine. Establish this as your primary project control number, such as 01225. With the work order setup utility in your CMMS, configure the next number to be 01225-01 (or 001 if you need more than 99 work orders) so the system will automatically generate subset numbers for the individual tasks to be accomplished under this main project work order. For example, the task of removing way covers will be work order 01225-01, sending way covers for refurbishment work order 01225-02, remove ball screw work order 01225-03, and so on. Create work orders following the project job sequence; don’t number tasks such as removals and re-installations together. After all of the work orders have been generated reset the work order numbering and create a work order summary for this project. As the work orders are completed, close them out and check them off of the project work order summary. Ensure that the work orders are signed off and turned in as they are completed. If a work order isn’t signed off in order that raises a flag and needs to be investigated. Work orders that are placed in hold can be placed in the tickler file to coincide with the date that they have been scheduled for reissuing.
When all project work orders are closed, close the primary project work order.
Reader tip provided by our frequent contributor Mike LeCompte
Maintenance Consultant
Maintenance Systems Development, LLC
http://www.maintsysdev.com
Tel: 843-761-8069
August 18, 2005
Reliability Tip
Commitment on the part of senior leadership is vital for any organization to implement and sustain a world-class Reliability Program.
Senior leadership must drive the change; it’s unrealistic to expect middle management to effectively change the organization. They must authorize expending resources for the initiative. They must evaluate the impact of competing initiatives and allocate resources appropriately.
To gain commitment, four things are needed:
• An honest assessment of the current state
• A clear vision of the future state
• A viable plan to go from here to there
• A clear and compelling business case with a Return on Investment calculation, presented in language that senior leaders understand
Tip provided by Life Cycle Engineering
http://www.lce.com
Tel: 843.744.7110 x267
August 18, 2005
Infrared Tip
Outdoor Infrared Survey Practices
Conducting thermal surveys of outdoor equipment. (Part 2) Archived at http://maintenancetalk.com/blog.php/tipsblog
Wind has a great effect on object temperatures. During windy conditions convective heat transfer is taking place, moving energy from the hot object to the air. The rate of convective heat transfer will depend upon the velocity of the wind, temperature differential between object and wind, and surface properties of the object.
Infrared cameras can not measure air temperature and therefore have no way of compensating for the cooling effect of wind and thermographers should not attempt to make a calculated guess about object temperature. Instead they should:
1. Wait until wind stops
2. Temporarily shield target from wind
3. Measure downwind side of target provided that object is sufficiently large
4. Always allow sufficient time for target to return to normal temperature once wind has diminished. If it is not possible to avoid wind, one should report wind velocity and direction when recording image data.
Tip provided by Electrophysics Corp.
Phone: (973) 882 - 0211
http://www.electrophysics.com
August 18, 2005
Vibration Analysis Tip
Considerations when setting up measurements (Part 2 of 4) Archived at
http://maintenancetalk.com/blog.php/tipsblog
Last week, when setting up a measurement to measure vibration, we discussed what type of equipment was to be monitored..
Next we need to ask, is the machine constant speed or variable speed?
Constant speed machines are fairly straightforward: identify the frequencies of interest and determine a maximum frequency range. Variable speed machines can be a bit tricky. How to ensure that you always capture the needed frequencies without taking excessive amounts of data each time?
The answer is order-based collection. We determine how many orders of data are sufficient and collection parameters are adjusted based on the inputted speed.
What are the primary frequencies of interest? See our next week’s tip.
Tip provided by LUDECA, INC.
ALIGNMENT * VIBRATION * BALANCING
http://www.ludeca.com
Tel: 305-591-8935
iPresentation Invitation: The process of spectrum acquisition
August 11, 2005
Lubrication Tip
The lubricating grease drums should be stored vertically. When the grease is scooped from the drum, the surface of the grease should be leveled or made convex. This will avoid oil bleeding in the grease drum.
The lubricating oil barrels should be stored horizontally in 3 O’ clock-9 O clock position so that both the bunks are parallel to the ground. This will avoid ingress of atmospheric moisture in the oil.
Reader tip provided by Vijay Deshmukh
Chief Research Manager
Indian Oil Corporation Ltd.
Faridabad India
Thank you Vijay - your Maintenance Tips is on the way!
August 11, 2005
Vibration Analysis 101 - Getting Started with Vibration Analysis
PdM-2005 Pre-Conference Workshop
Predictive Maintenance Technology
Conference & Expo
September 19-22, 2005
Atlanta, Georgia
This one-day course will provide a detailed introduction to vibration measurement and analysis. This course does not assume any prior experience or knowledge. Students will leave with a solid understanding of vibration basics, how to take good measurements, and how vibration can forewarn you of rotating machinery faults.
Each student will receive a booklet of the slides (which can be used to take notes during the course), an excellent quick-reference mouse pad, a CD containing a library of vibration-related presentations, and access to the Mobius eLearning course “An Introduction to Vibration Analysis” – a $100 value.
To set the stage, we begin with a quick tour of the world of vibration monitoring and analysis. You will see and hear real vibration from real machines so that you can see what can be achieved by collecting and analyzing machine vibration.
We will then carefully go through the basics of vibration: what is it, where does it come from, how we measure it, how we describe it, and how it relates to the condition of the machine. We will discuss vibration measurement: data collectors, route collection, how sensors work, repeatability, and most importantly, the do’s and don’ts of data collection.
Next we will describe the time waveform in basic terms, and introduce the vibration spectrum. We will show how peaks in the spectrum relate to the rotating components in the machine.
And finally, we will cover the practical side of vibration analysis – how to view vibration spectra to determine if the machine has a fault condition. We will cover imbalance, misalignment, looseness, and bearing faults.
This course should appeal to you if you need to understand what vibration analysis is all about. It is ideally suited to the person who is new to a vibration monitoring group. If you are involved with another predictive maintenance technology and want to understand vibration analysis; this course is ideal. And if you manage a condition monitoring group but have never practiced vibration monitoring yourself, this course will enable you to understand the job your vibration team has to perform.
Join Jason and 30 other presenters, workshop leaders and learning lab directors at PdM-2005.
To learn more call toll free (888) 575-1245 or…
August 11, 2005
Maintenance Tip
Taper loc care: To avoid abrasion and corrosion wear to the allen head bolts (specifically material handling fans)add a small amount of silicone to the bolt head. When it’s time to remove the allen bolt dig out the silicone. The bolt will look like new.
Reader tip provided by Don Carmen
Vibration Tech
Weyerhaeuser M.D.F.
Eugene OR USA
Thanks Don - your Maintenance Tips hat is on the way.
August 11, 2005
CMMS Tip
When generating work orders, run each department’s separately. (This would also work if you want to run each individual employee separately). This assumes that your CMMS will let you run the work orders by department or individual.
Change the paper, using a different color for each department or individual; always using the same color for that department or individual.
This speeds up sorting time and also makes it easy for the users to identify/find their work orders - a green, blue, yellow, etc… page stands out in a sea of white. It also makes filing a lot easier.
Tip provided by OOPS!/Oz user Anita Suennen from Tyco
Thanks Anita - your Maintenance Tips hat is on the way!
August 11, 2005
PdM-2005 Predictive Maintenance Technology Conference & Expo
Mark Your Calendar!
Predictive Maintenance Technology Conference
September 19-22, 2005
Atlanta, Georgia
Please join us for PdM-2005, the Predictive Maintenance Technology Conference & Expo from September 19, 2005 through September 22, 2005 in beautiful downtown Atlanta Georgia.
This conference is designed for beginners and seasoned professionals.
Not since P/PM Magazine’s Predictive Maintenance National Conference sponsored throughout the 90’s (and no longer in operation) has one event provided a venue for the technologies required for reliable machinery operation.
PdM-2005 will focus on:
• Vibration Analysis
• Airborne Ultrasound
• Infrared Imaging
• Motor Testing
• Oil and Wear Particle Analysis
• Other condition monitoring technologies
Bring your entire PdM team for 4 days of focused learning.
To register or learn more please call toll free 888-575-1245 or…
