Ultrasonic Alarm Parameters, i.e., HFD, Spike Energy (™Entek), Acceleration Enveloping (™SKF/CM), Peak View (™CSI), Demod (™DLI), or other trade names are all methods of filtering the original transducer output to magnify and detect early high-frequency REB, lubrication, and gear defect problems. These alarm parameters are very useful, but often misused.

Ultrasonic analysis provides two measurement parameters;

(1) The Overall Ultrasonic Trend, commonly referred to as the “HFD”, or High Frequency Detection parameter.

(2) The Demodulated, or Ultrasonic Spectrum parameter.

The overall HDF trend is typically alarmed and trended for changes that might indicate a friction or impact source in the REB or gear system. Alarms are usually set based on OEM recommendations (based on RPM, bearing diameter, etc.,) then reset statistically as more data is collected. These alarms are “Peak” or “threshold” type. The ultrasonic spectrum, or demodulated spectrum on the other hand should never be alarmed. Numerous variations in transducer type, placement, sensitivity to temperature, operating conditions or other measurement parameters can alter the final spectrum amplitude levels. These amplitudes are a function of special filtering, rectification, peak detection, and enveloping of the original signal. These conditions make the spectrum peaks virtually unpredictable.

Ultrasonic Analysis Rule #1: Alarm and Trend the HFD Overall Level

Ultrasonic Analysis Rule #2: Never Alarm the Demodulated Spectra

Tip from Dan Ambre, P.E., Full Spectrum Diagnostics, PLLC,
http://www.fullspec.net

Register for Dan’s Introduction to Vibration Analysis Workshop at PdM-2006

When Precision Balance can endanger the machine?

The vibration industry in New Zealand has been actively “preaching” the benefits of precision balancing machinery, where practical, to improve machine life. By precision I mean balancing to ISO 1940 G1 or better. Now many industries specify G1 on new equipment and ask for G1 for insitu balancing on even large machines.

The following example is a caution to those who blindly follow this idea without being fully aware of all of the machine’s possible operating modes.

The case in point is a physically large vertical hydro generator which had just been refurbished, with a new runner and rebuilt generator rotor.

Output 55 MW, generator rotor weight 230 tonnes, balance weight radius 3 meters, normal RPM 100.

The trick to balancing these machines is to get a big enough trial weight. We use, as a rule of thumb, force from trial weight equal to 10% of rotor weight (mass x 9.81). For this machine the trial mass worked out at 350 kgs. The next trick is to get this mass on the machine. A crane was of great assistance and the weight was fitted to internal rotor bracing. Following this a final weight was calculated at 128 kgs. With this fitted a residual of 6 kgs was indicated well within the 7.6 kgs allowed for G1. The original vibration was 250µm p-p and in a balanced state 9µm p-p (Not bad on meter diameter shaft) Note this balancing was done with the machine un-excited. i.e. a purely mechanical balance.

The machine was then excited and the 1x vibration immediately jumped to 260 µm p-p. The rotor had a magnetic imbalance probably due to the rotor not being perfectly round and or the magnetic field from the 60 poles being not totally even. The magnetic imbalance increased with load.

The client was keen on obtaining a G1 balance at the normal operating load i.e. flat out and requested that the magnetic imbalance be corrected to G1 at full load.

It was now time to take a step back and look at all the implications. Based on the balance data a full load balance weight was calculated. It was then estimated what would happen if this weight was fitted and the machine tripped at full load. If the machine trips at full load two things happen almost instantaneously. 1. The excitation and therefore the magnetic imbalance disappears and 2. the machine over speeds to 150+ RPM before the governors close.

We would now have a machine with a large imbalance causing an estimated 900 µm p-p motion on the shaft.

The final solution was to balance to G1 at half load so that the machine was reasonable at no load and full load but still safe under all conditions.

This Tip was one the tips selected from the PdM-2006 Maintenance-Tips Challenge and was provided by
Simon Hurricks, Machine Dynamics Engineer, Genesis Energy, Huntly, Waikato, New Zealand

Thanks Simon - your PdM-2006 Proceedings CD and Maintenance-Tips hat will be shipped as soon the CD is published.

More Balancing Resources and Links

PdM-2006 Post-Conference Workshop
September 15, 2006
Chattanooga TN

This interactive one-day workshop led by Howard Penrose PhD, CMRP, will pit teams of five against each other in the challenge of maintaining their electric motor systems for the greatest positive impact on business. The assortment of teams will provide the attendees a unique series of options that they can bring back to apply at their companies.

Each team will select motor maintenance philosophies such as reactive, proactive, outsourced or other hybrids and styles. A budget and options will be assigned and technologies purchased for application for fictional sites. Each site and options will end up being unique, including within the same company structure, and also tailored by the players.

The day will start with training in the use of the game, then we will break up into teams and the moderator. Budgets will be assigned to the team administrators for distribution amongst each team, cards related to the specifics of the motor systems for each site, the purchase of technology, personnel and philosophies and outsourced capabilities. The game will be time-limited to the end of the day, 52 moves (52 weeks) or until one winner emerges. Actions and reactions will be based upon probability with decisions and philosophies affecting the outcome. The objective is to have a remaining budget and to stay within production loss limits. If either limit is crossed, the team is out of the game.

Work with your motor management budget and production loss limits. The team with the most toys and money at the end… WINS!

Space is limited and filling up fast so please call toll free (888) 575 1245 or…

Register for a PdM-2006 Workshop online

To minimize human error, the culture should:

a. allow the boss to hear bad news.

b. identify and address potential failures proactively before they materialize .

c. realize that punishing people does not necessarily eliminate the risk of recurrence of the same failure somewhere else.

d. not blame the regulator for failing to monitor closely enough.

e. make the concept of Root Cause Analysis an integral part of the organizational culture.

Tip provided by Reliability Center Inc.
http://www.reliability.com

Learn more about Basic Failure Analysis for Predictive Maintenance Professionals Workshop at PdM-2006

Sometimes it is hard to cost justify using sterile oil sample bottles especially when the ISO cleanliness targets are not very low. But to ensure that the lower cost bottles are as clean and particulate free as possible, we use canned air (computer/keyboard cleaner) to clean the bottles. A couple of blasts to the bottle and lid just takes a couple seconds and has proven to work very well, giving consistently clean bottles.

Reader tip provided by Jerry Baker
PdM Team, Lubrication
Tate & Lyle
Loudon TN

Thanks Jerry - Your Maintenance Tips hat is on the way. I hope we see you at LubricationWorld-2006 in Chattanooga!

Learn more about LubricationWorld-2006

Last year the 13th Annual SMRP conference drew over 950 maintenance and reliability professionals. Exhibitors raved about the quality of the leads they got from professionals who actually make decisions on maintenance and reliability products and services. Don’t miss this year’s event in Birmingham, Alabama where we’ll be expecting an even larger group.

Please note SMRP contact information has changed! SMRP can be contacted via telephone at (703) 245-8011, Fax 703-610-9005 and e-mail

Learn more online

Here are some items to consider/include when printing inventory labels:

-Barcode for Item No.
(To prepare for a barcode solution.)

-Item No.
(To let end users know the item number for proper check outs/returns.)

-Item Description
(To let end users know the description of an item.)

-Date Added
(To let end users know how long the item has been in use.)

-Unit of Measure
(To let end users know how to count an item. We found this necessary when temps were hired to perform a physical inventory and they counted boxes instead of each and visa versa.)

-Unit Cost
(To let end users know the value of an item. We sometimes found users quite surprised at the unit cost of an item. As a result, better care was paid towards each item.)

Hope this helps and have an excellent rest of the week!

Tip provided by CMMS data group
http://www.cmmsdatagroup.com

Click here to view CMMS data group’s

I am responding to the following discussion between Ray Beebe and Evan Smith:
=====================================

The following tip was posted in the July 7th email:

“Maintenance Tip”
The purpose of maintenance

The fundamental purpose of maintenance in any business is to provide the required capacity for production at the lowest cost. It should be regarded as a RELIABILITY function - not as a repair function.

By Ray S. Beebe, Author, Predictive Maintenance of Pumps Using Condition Monitoring”

=====================================
Response from Evan Smith:

I agree in spirit what is being said, but I worry about the potential literal translation that can occur with these statements, especially the first, that “maintenance’s purpose is to provide the required capacity at lowest cost.”

I believe maintenance is a key player to provide needed production at lowest price but I look at this as a joint team effort. In this effort there are four team players, Business Management, Engineering, Operations, and Maintenance. Business management determines the market needs and evaluates the available economics and needed capacities. Engineering uses available economics and needed production to determine designs and construct the process. Operations manage the equipment and incoming resources to produce the product. Maintenance provides specialized reliability activities, monitors equipment for pending failures, and does repairs when needed. It takes all four groups working together to provide required capacity at lowest cost.

All too often one of these four groups falls short and the attempted pass the blame game begins. With maintenance the last to become involved with equipment, they can be the first to get blamed. Using a pump as an example, no amount of maintenance can help if the system is not designed correctly. Or even with a good design if it is not operated within design parameters. If the suction head is not there, whether from supply tank level allowed to drop too low by operations or an engineering marginal design, production will not meet needs and pump failures will occur. No amount of “maintenance” will improve reliability in these cases.

In summary, my concern with a statement that maintenance’s purpose is to provide needed capacity, that is the case when wear is the factor causing low capacity.

Through positive maintenance efforts, condition based monitoring, good troubleshooting, root cause analysis, and other functions, with involvement of the entire team a difference can be made. The key is to not let one group move into false self glory at the expense of another.

Assure all equipment and systems used to manufacture and develop product are safe to use, pose no threat to the environment, are available to produce product, without interruption at a cost that Flex Products Inc. can afford.

==================================
Response from Alexander D. Douglas Jr., Mgr. Equipment Reliability & Maintenance, JDSU, Flex Products Group:

I believe that they are both correct but did not elaborate to clarify.

Here is my take away.

In any enterprise worth its salt where equipment, hardware, facilities, systems etc, are used to produce product or provide a service, someone needs to be responsible for equipment performance. I am using the term equipment here as a catch all.

Most of the time its clear who isn’t responsible for “equipment” performance, like Sales, Accounting, Finance, Quality etc.

So the performance responsibility for equipment performance typically falls into one or more of the following…. Manufacturing, Engineering, Maintenance, Operations, etc.

One way to organize is as follows.

Engineering specifies the recipe “PROCESS” for making product…. And specifies the “TOOLS” that Operations uses to make the product….

The recipe and the capability of the tool together provide an expectation… typically called in RCM speak “what the user wants” or FUNCTION.

So a Functional expectation is created that manufacturing / operations come to rely on.

Manufacturing / Operations reports deviations to the functional expectations…. Along with the consequences. Down-time, injuries, yields lost, product lost, throughput reductions, environmental damage, etc.

Maintenance collects those reports, applies forensic investigation and analysis (using either a single maintainer or a team approach depending on the scope or the deviation) on the important deviations and generates a corrective action.

Those corrective actions could be assigned to anyone…. Operations, Manufacturing, Engineering, Maintenance, an outside consultant, an outside vendor and could include one or more of the listed corrective actions.

Those corrective actions could be:

1) Modifications to Equipment
2) Modifications to the manufacturing recipe
3) New training
4) New Proactive Maintenance tasks
5) Changes to existing Proactive Maintenance Tasks
6) Changes to training
7) New Equipment
8)Changes to work instructions

……What ever it takes to mitigate the functional failure.

Maintenance takes the lead… because Maintenance is the second functional group to encounter a functional failure. Operations are first, however operations should focus on operating…

Maintenance needs to focus on the following:

Assure all equipment and systems used to manufacture and develop product are safe to use, pose no threat to the environment, are available to produce product, without interruption at a cost that the enterprise can afford.

Take the lead…. Get er done….

=========================================

Thank you for your reply Mr. Douglas!

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