83
EMAIL TIPS A Learning Publication from Full Spectrum Diagnostics
Vol. 83 April 2012
The Destructive Power of ElectroErosion
Diagnostic Testing Can Provide the Answers
EMAIL TIPS Volume 83 April 2012
Far and Away
2012 Training Schedules
Some new tools are in play with the use of the new Issuu.com publication format. The Full Spectrum Diagnostics distribution for Email Tips is nearly 3,900 strong. With only indirect knowledge of recipients and sharing the reach of this publication was only a guess. Until now.
Core Training Courses: • Intro (IVA) – VAI – VAII – VAIII
The statistics capability in the new file sharing platform now provides a world-wide view of the Email Tips “traffic”.
Concentrated Training Courses: • TWF – Spectrum – Phase – Bearings Specialty Training Courses: • ODS/Modal – Precision Balancing
Cover: The cover this month provides a close-up view of a rolling element bearing virtually destroyed by “fluting” or “electro-erosion” phenomena.
The February & March issues reached across the globe with over 700 individual readers. Dan Ambre [ModalGuy@aol.com], (763) 577-9959 www.fullspec.net
This Month’s Features:
Electro-erosion occurs in rolling element bearings when a current is passed through the bearing instead of a ground source. Variable Frequency Drives (VFD’s) installed on AC induction motors allow speed control; however their drive switching frequencies can also induce stray shaft currents in the motor shaft. Electro-erosion can also be caused by improperly grounded DC Drives, or even from improper grounding while welding on a machine with rolling element bearings.
The Time Waveform – The Shape of the TWF dictates the Frequency Content in the FFT The Frequency Spectrum – Fluting, or ElectroErosion in Rolling Element Bearings Diagnostic Testing : Tips for exploring the “next” phase of analysis based on a logical process. Product Review: Dytran 7543A Tri-axial DC Accelerometer & Acquisition Software
Another up close look
Time Domain Tips: The sha ape of a time waveform ca an indicate the e harmonic content that will be b produced in the Fa ast Fourier Transforrm (FFT). A Sinu usoidal Wa aveform will produce a single fundame ental freque ency with no n harmoniccs in the spectrum m. This is typ pical of a rotor unbalance response. r A Trian ngular Wavefform has a fundamental frequency and EV VEN harmonicc multiples, however h the harmonics are atte enuated in an a exponential fashion with w higher frequenccies. This iss a typical sig gnature from looseness or bearin ng clearance issues. A Squarre Waveform m produces a fundamental frequency, but also o induces a series of OD DD harmonicc multiples. The odd d harmonic am mplitudes dim minish in a line ear fashion in the higher frequen ncy range. This T signature e can be a result of o mount loosseness or a partial rub (waveform truncatio on) condition.. The Saw w Tooth Wa aveform will produce a fu undamental frequenccy with an OD DD and EVEN N harmonic series. s This waveforrm is a resultt of impacts such as defe ective gear teeth orr cracked bearing racewa ays. Signal processing analysis associatted with ultrasonic u demodulation d accountts for the recctified wavefo orm shape. This T pulselike wavveform provid des a relative ely flat specttral energy responsse is ideal forr exciting natu ural frequenccies (bump, impact testing). t
Figurre 1.0 Frequency Responsse Table
Finally, a Random Waveform will w produce essentially “ALL” harmonics h orr broadband energy from m multiple frequenccy sources th hat will not pro oduce a domiinant peak. Rather a jagged noise floor resp ponse is crea ated whose amplitud de will increa ase or decrea ase with the amount of (energy)) friction in n the sourc ce. Typically indicates lubrication issues in Rolling R Eleme ent Bearings.
Hardw ware Insp pection Tip: T Electro-Erosion, Arccing, Stray Currents, or o Fluting. Whateve er you call it, it still resultts in the earlly death of rolling element bea arings. In the past prroblems of electrica al discharge in rotating machinery wass limited to DC type e motor system ms. Defectiv ve insulation or o improper groundin ng occasiona ally resulted in n bearing dam mage when these sttray shaft currents went to t ground via a the least resistive e path. This path, many times, was across the rolling element e bearings. The res sult is anywh here from a “milky” or o “frosted” fin nish on the su urface to a more m drastic “grooved d” or “washbo oard” damage e to the racew ways. The problem m is more pre evalent today due to the in ntroduction of Varia able Frequen ncy Drives (VFD’s) ( for AC speed control. Either way, w the specttral signature e is the same. The fault does no ot occur at th he typical Bea aring Defect frequency; rather the damage creates a se eries of high h-frequency peaks in the spectrrum. This “haystack” “ off peaks is typicallyy found in the 100,000 to 180,000 CPM (1600-
Figurre 2.0 Fluting – Electro Ero osion Example es 3000 Hz) H frequenccy ranges. The spacing of the clusterss of peaks occcurs at the defect d frequen ncy of the inner ra ace, outer racce, or sometim mes both race eways. If the analyst neglects to collect a high-ffrequency spectru um on his motor this fault can easily e go undetected. If you have Variab ble Frequenccy Drives, this me easurement iss a must.
Spectrum Analysis Tip: The cartoon to the right provides a generic look at the frequency content of Electro-Erosion or “Fluting” as it appears in the vibration spectrum. First, the frequency range. Typically the haystack of peaks finds its way into the [100k CPM to 180k CPM] range. This higher frequency range is a bit higher than the ranged used to detect Rolling Element Bearing (REB) defects. However, since the source of the problem is most often associated with motors and variable frequency drives, the spectrum used to detect Rotor Bar Passing Frequency (RBPF) will easily cover this range. Secondly, the haystack itself is more orderly than one would think. The peaks are non-synchronous and regularly spaced. The spacing is related to one of the four bearing defect frequencies; FTF, BSF, BPFO, BPFI. The fundamental defect frequencies themselves do not appear, but the haystack spacing suggests which bearing component is causing the problem (raceway, rolling element, or cage).
Figure 3.0 Fluting – Cartoon Spectrum Depiction
Next, the amplitude should be of some interest. While the number of peaks can be extensive, suggesting a significant energy source, the amplitudes can be VERY SMALL. Also, there can be more than one source. The spectra at the right show BOTH the BPFO and BPFI raceway fault spacing in multiple “haystacks”. Finally, the Ultra-sonic Demodulated Spectrum (HFD) should include peaks associated with this high frequency, modulated source. The center frequency is likely a natural frequency of the bearing, carrier, or housing, while the modulation is depicted as the cluster of peaks modulated to the REB fault frequency.
Figure 4.0 Fluting – AC Induction Motor [BPFO & BPFI]
Figure 5.0 Fluting – AC Induction Motor [BPFO & BPFI]
Approaching Diagnostic Testing The Icons shown on this month’s cover and to the right are used on the Vibration Analysis Periodic Table to direct the analyst to appropriate diagnostic techniques that may guide his analysis. When analyzing vibration data, one can appreciate a little insight into the next logical step or data collection to perform. The icons indicate that a Phase Analysis can be performed for this fault, a Time Waveform may provide confirming or refuting data, an Orbit analysis is possible, the Ultra-sonic frequency range should be measured, a Natural Frequency (bump) test can help, or that there is a Formula or calculation associated with this type of fault. Figure 6.0 The Vibration Analysis Periodic Table Of course, the analyst will still need to know perform the recommended test. That is where courses come in handy. The Periodic Table is narrow the field and get the analyst to the diagnosis when time is of the essence.
how to training here to proper
Product / Literature Reviews:
Figure 7.0 Diagnostic Recommendation Icons
AcqSense: Intelligent Sensor Acquisition Software A recent Dytran Sensor innovation takes advantage of USB connections on any computer to both power the device and acquire measurement data. The 7543A tri-axial sensor itself is quite impressive with a frequency range from DC to 1600 Hz. But the innovation does not stop there. The sensor and associated software application can be setup to store not only the x, y, z transducer response, but also the pitch and roll response. The software can calibrate the sensor, provide offsets relative to installation orientation and can detect and store the sensor temperature. The sensor / software package is scheduled to hit the consumer market soon. The applications range from seismic response to modal analysis. Please note that Full Spectrum Diagnostics is NOT a Dytran sales representative, nor are we profiting from this tech review. We are just a bunch of geeks that like new products and technology. Full Spectrum Diagnostics has no financial connection with any of the books, papers, reference materials, or application notes reviewed in this newsletter. All of the reviews of these materials are first-hand opinions of Full Spectrum Diagnostics’ analysts and instructors.
Figure 5.0 Dytran 7543A Tri-Axial DC Accelerometer &Associated Software Application
REMAINING: 2012 CORE VIBRATION TRAINING SCHEDULE IMPLEMENTING A SUCCESSFUL PdM PROGRAM JUN 19-20 Cameron, WI 2012-PdM-01 Tuition: $ 945.00 / 2-day Format Proficiency Test: Included
INTRODUCTION TO VIBRATION ANALYSIS APR 17-18 Knoxville, TN
2012-INT-04
Tuition: $ 945.00 / 2-day Format Proficiency Test: Included
REMAINING: 2012 SPECIALTY VIBRATION TRAINING SCHEDULE MODAL & ODS ANALYSIS 2 JUL 24-26
St. Paul, MN
2012-ODS-02
For In-Plant Training: ModalGuy@aol.com Tuition: $ 1,595.00 / 3-day Format One Month ME’scope Software Included
CONC TIME WAVEFORM ANLAYSIS JUN 05-06 Cedar Rapids, IA 2012-TWF-01 NOV 27-28 Chillicothe, OH 2012-TWF-02 Tuition: $ 945.00 / 2-day Format Proficiency Test: Included
CONCENTRATED SPECTRUM ANALYSIS VIBRATION ANALYSIS I APR 24-27 SEP 11-14 DEC 11-14 DEC 18-21
Wheeling, WV Chicago, IL Charlotte, NC New Orleans, LA
2012-VA1-03 2012-VA1-04 2012-VA1-05 2012-VA1-06
JUN 26-27 Brookfield, WI 2012-CSA-01 JUL 17-18 Davenport, IA 2012-CSA-02 OCT 02-03 St. Paul, MN 2012-CSA-03 Tuition: $ 945.00 / 2-day Format Proficiency Test: Included
Tuition: $ 1,295.00 / 3-day Format Certification Exam: $ 200.00
CONCENTRATED PHASE ANALYSIS
VIBRATION ANLAYSIS II
Tuition: $ 945.00 / 2-day Format Hands-on Exercises: Included
SEP 18-19 Davenport, IA 2012-CPA-01 MAY 08-11 MAY 22-25 JUL 10-13 SEP 25-28
Chicago, IL Cumming, GA St. Paul, MN Cedar Rapids, IA
2012-VA2-03 2012-VA2-04 2012-VA2-05 2012-VA2-06
CONCENTRATED RE BEARING & GEAR ANLAYSIS OCT 16-17 Cedar Rapids, IA 2012-BGA-01
Tuition: $ 1,395.00 / 3-day Format Certification Exam: $ 200.00
Tuition: $ 945.00 / 2-day Format Proficiency Test: Included
VIBRATION ANALYSIS IIIa
VIBRATION ANALYSIS FOR MOTOR SHOPS
OCT 23-26 Leesport, PA
2012-VA3-01
AUG 28-30 Charlotte, NC 2012-VAM-01 DEC 04-06 St. Paul, MN 2012-VAM-02
Tuition: $ 1,595.00 / 4-day Format Certification Exam: $ 200.00
Tuition: $ 1,295.00 / 3-day Format Hands-on Exercises: Included
PRACTICAL VIBREATION ANALYSIS IIIb
PRECISION BALANCING
AUG 21-24 St. Paul, MN 2012-PVA-01
MAY 01-02 Cedar Rapids, IA 2012-BAL-02 AUG 07-08 Brookfield, WI 2012-BAL-03 NOV 13-14 Wheeling, WV 2012-BAL-04
Tuition: $ 1,595.00 / 4-day Format Certification Exam: $ 200.00
Tuition: $ 945.00 / 2-day Format Hands-on Exercises: Included
!!! NEW !!!
THE VIBRATION FAULT GUIDE The Vibration Fault Guide is a 110-page indispensable asset for every vibration analyst, as well as a helpful tool to bridge the gap between the analyst and his management staff. Some 45 Rotating Machinery Faults are Identified and defined. Conveniently sized at 3” x 6”, it easily fits in your pocket for everyday use!
GUÍA DE FALLAS DE VIBRACIÓN Este manual consta de 110 páginas y fue compilado por Full Spectrum Diagnostics como referencia rápida para la industria de Mantenimiento Predictivo y Monitoreo de Condición. La guía incluye ejemplos de espectros, formas de onda, definiciones de fallos y reglasde análisis de fase para aproximadamente unos 45 problemas que se pueden presentar en maquinaria rotativa. También incluimos varios estándares de especificaciones de vibración, guías para definición de bandas de alarmas, fórmulas y definiciones de Procesamiento de Señales. Es suficientemente pequeño como para llevarlo en la bolsa de su camisa ( 3.5” X 6.0”), pero su contenido es tan grande que podría ser considerado como una guía de referencia esencial para la industria del Monitoreo de Condición.
THE VIBRATION TECHNIQUES GUIDE The Vibration Analysis Techniques Guide is a 108-page pocket sized information treasure trove. Information on dozens of analysis techniques, specifications and data presentation formats are included. If you liked the Vibration Fault Guide, your next educational step should be the Vibration Analysis Techniques Guide get yours now at:
Order now at: http://www.fullspec.net/store.html Or by Phone @ (763) 577-9959
BULK DISCOUNTS & BUNDLE PACKAGES AVAILABLE!
THE VIBRATIION ANALYSIS WALL W CHA ART The Vibration V Ana alysis Wall Chart C is a 46 6” x 36” Full-Color Laminated Referrence for you ur drab officce wall. The e overall Alarm cha arts in the center of th he chart are e surrounde ed by group pings of ove er 40 dominant rotating g machinery faults. These groupings by frrequency co ontent and direction d allow the analyst to “narrow w-down” the e potential faults and zero-in on o current vibration v pro oblem. The e Wall Charrt is the ultim mate compa anion to the e uide and the e Vibration Techniques T G Guide refere ences. Vibrattion Fault Gu Orderr now at: Htttp://www.fulllspec.net/sto ore.html Or byy Phone @ (763) 577-99 959
BU ULK DISC COUNTS & BUNDL LE PACKAGE ES AVAIL LABLE!
fssd
THE VIBRATION ANALYSIS PERIODIC TABLE This Full Color Laminated 8 ½ x 11 inch card-stock table provides a “quick-look” method of distinguishing one machinery fault from another and suggests Diagnostic Tests or formula that may be used to build a case and make the call! This Chart is a “Logical” analysis tool that classifies vibration problems by Frequency Content and Directional Response. The potential vibration sources are instantly reduced based on the analyst’s current measurement data. The Table “forces” the user to think logically and classify faults accordingly. Individual Faults are Foot Note Referenced to the Vibration Fault Guide for a more detailed review. If you think the Vibration Fault Guide is valuable, your next educational step should be the Vibration Analysis Periodic Table! Get yours now at: www.fullspec.net, or by phone at 763-577-9959
BULK DISCOUNTS & BUNDLE PACKAGES AVAILABLE!
INSTRUCTORS:
Full Spectrum Diagnostics’ Lead Instructor & Seminar Author is Dan Ambre. Dan is a graduate of The University of Iowa with a Bachelor’s degree in Mechanical Engineering, and has completed additional graduate level course work in Engineering Dynamics from The University of Illinois at Chicago, and Florida Atlantic University. Dan is a Certified Vibration Analysis Level III Instructor with over 16 years of Vibration Training and Certification Experience. Dan’s 25+ years of vibration experience in the Aviation & Aerospace Industries comes from positions at Sundstrand Aviation Corporation and Pratt & Whitney (United Technologies Corporation). This fieldwork includes Vibration & Acoustic testing, Rotor Dynamics analysis of high speed Rotor Systems, Experimental Modal, and Finite Element Analysis. His consulting experience base comes from positions at Technical Associates and Full Spectrum Diagnostics, which he founded in June of 2000. He is a Registered Professional Engineer in the States of North Carolina and Minnesota. Dan can be contacted by phone at (612) 875-9959, or via Email at ModalGuy@aol.com
Since 2002, after years of close association, Louis G. Pagliaro joined Full Spectrum Diagnostics. Lou fulfills multiple roles as our Seminar Sales Coordinator, Senior Instructor and course content co-author. Lou is a certified Level III Vibration Analyst (since 1996) and was recently re-certified by American Society of Nondestructive Testing as an ASNT PdM Level III in Vibration Analysis. He has over 30 years of varied industrial experience, including Maintenance Management, Vibration Analysis, Vibration Training, Certification, and course development in areas of Noise Control, Precision Maintenance, Precision Alignment, Preventive Maintenance, and Maintenance Skills Enhancement. His worldwide teaching credentials include instruction of TAC, Update International, CSI, Entek and SKF customers in eight countries. Louis is a graduate of Niagara College in Welland, Canada. Lou can be contacted by phone at (704) 577-3953, or via Email at Lpagl@aol.com.