Another method of visual monitoring for nut / bolt or screw tightness is to apply some brightly colored nail polish to the outside of both the bolt and the nut.

Bright red is my choice as it is easy to see even in dimly lit work locations. It also goes a long way in keeping the device tight as it now acts like a liquid locking application. This method works well even in moderately harsh environments that experience moisture, heat or vibration.

The most difficult aspect of this maintenance activity is the ‘ribbing’ you’ll have to withstand from your co-workers as they demand to see your nails!

Reader Tip provided by Doug Walker, Technical Asst. III, Manitoba Hydro, Winnipeg, Manitoba, Canada

Thanks Doug - your Maintenance Tips hat is on the way!

Submit your own tip and get a Maintenance-Tips hat

From Richard Danks, NASA

Regarding the tip below in your recent Tips: I have known of situations where threaded fasteners have experienced fretting due to vibration. The nut may not move from the original torqued position, but due to thread wear, the nut can be unfastened using only your fingers. The scribe method as described below can not indicate this particular condition.

Tip for Inspecting bolt/nut tightness
First: Install a nut to proper tightness.

Second: Scribe a line through the nut to the equipment frame around the nut

On PM inspections just verify that the scribed line is unbroken.

Tip provided by Joel Levitt
=================

Richard - Any tips to detect or prevent this condition?
- Terry O

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

Sorry for the long delay in responding – I wanted to check with a couple of my sources. As far as preventing fretting – my original exposure to this was in an article written by a motorcycle technician dealing with proper preparation for racing. In this high performance situation, vibration is exacerbated. From what I recall using adhesive fluids to bond the threads together is one method that was suggested in the article. Personal experience tells me this does work.

The fretting phenomenon is caused by molecular level vibration between mismatched surfaces (surface finish, hardness, etc.). I am told the molecular residue from the vibration acts as a lubricant. The glue approach fills the voids between the threads eliminating the fretting and holding the fastener together.

I was also informed that for critical applications on certain military vessels (and maybe spacecraft), an interference fit fastener is used where the torque applied to the threads in effect welds the threads together. Clearly in this application, the fastener is not meant to be reused should the fastener need to be undone.

I hope this helps,
Richard

Thanks Richard! - we all appreciate the information - Terry O

More Maintenance Tips

Learning Event 1
Root Cause Analysis
February 21 –22
Charlotte, North Carolina

Learning is a two-way street! The typical method of transferring information to the Reliability Community has been a one way street — speaker to participant with very little input from you, the customer. RELIABILITY Magazine offers a new, more interesting, meaningful and significant method of learning:

• You determine conference content. Extensive pre-conference surveying of Event Topics will pre-set the conference agenda.

• Benchmark your Program/Process. Benchmark your current program/process with other participants via on-site surveying using audience response technology – participants provide data in complete confidentiality but view group benchmarking data instantaneously!

• On-site data interpretation. Pre-conference and on-site survey results will be presented and discussed as a “team” – participants, moderators and plant commentators will comment/ask and answer questions.

• A customized plan for the future. New technology will offer attendees the opportunity to develop a process map defining and/or refining their own program/ process.

• Achieve management buy-in. A comprehensive report based on preliminary and on-site surveying justifying to management what changes need to be made at your facility.

• On-going support. Our learning process doesn’t end once the conference ends! Attendees will be provided with exclusive web-based tools for on-going support and communication with conference attendees including private message boards.

Conference participation is highly restricted to provide ultimate interaction and individualized instruction so early registration is highly recommended. Register today by calling (888) 575 1245 ext 6 to register over the phone or…

Click here to learn more or register today

Mounted Resonance – See what you’ve been missing:

Even if you have selected an accelerometer that is specified for the frequency ranges you are interested in monitoring, your data collection method could be affecting the data you are using to make critical calls. Are you sure that the data you are collecting is accurate and complete?

The “Transmission Region” of an accelerometer is defined as the usable frequency range of the accelerometer, and will be specified at +/- 5%, +/- 10%, or +/- 3dB. Most analysts will select a sensor with specifications in this range that match the application they are monitoring; for example if data at 8 kHz is important to an analyst, they will make sure that their sensor is rated for 10 kHz or 15 kHz at 3dB.

The “Amplification Region” is defined as the area in which resonance is occurring and creating significant signal gain. Measurements in the amplification region should be taken with care using special programs provided by the data collector manufacturers. The “Isolation Region” is defined as the area above resonance that has unpredictable gain, phase, and amplitude. The isolation region should never be used for measurements.

It is interesting to note that the mounting method used for data collection – whether online or portable – can affect the Transmission, Amplification and Isolation Regions of the sensor by the affects that the mounting method has on the stiffness and mass of the system of the sensor & mount. Therefore, the analyst that chose a 15 kHz sensor to monitor a fault at 8 kHz might miss that data because the isolation range of that sensor when mounted on a magnet might be below the 8 kHz target.

In summary: it is just as critical to consider the mounting method as the sensor specifications used for a given application. Are you missing data that is critical to your vibration program due to choices of mounting methods?

Tip provided by CTC (Connection Technology Center, Inc.)
800-999-5290 x 809 (in USA)
585-924-5900 x 809 (international)
http://www.ctconline.com

Take this iPresentation Tutorial to learn more…

Drop by DMSI’s IMC-2006 booth (N704) for a chance to win a Windows Mobile PDA! While visiting, learn about one of the greatest facilitators of the reactive to PdM change ...Asset Basic Care on Mobile Computers, InspectCE.

See you at IMC booth N704!
http://www.maintenanceconference.com

Please call DMSI at 604.984.3674 or…

If you’re not attending IMC-2006, learn about Asset Basic Care

Bolt-Bound Made Easy: Optimizing Alignment

When you get bolt-bound or base-bound on a critical machine train, usually one that is very difficult to move, it is not enough to just be able to fix individual pairs of feet to obtain alternative shimming or moving solutions. You need even more flexibility: the ability to minimize moves across all the feet. The concept of stationary and movable machines is obsolete: All machine feet are movable under given circumstances, so it is essential to be able to find the minimum corrections necessary to align to any conceivable centerline, including fully optimized centerlines, or centerlines optimized among any desired number of fixed or movable feet in any combination. Such flexibility is imperative when working with machinery on the critical path. Therefore, look for this capability when selecting you laser alignment system.

Tip provided by LUDECA, INC.
ALIGNMENT * VIBRATION * BALANCING
http://www.ludeca.com
Tel: 305-591-8935

Learn more by playing Ludeca’s Rotalign ULTRA trivia

Don’t Plan Anything, or Make Rotten, Useless Plans (5 of 12)

It is a proven fact that good planning reduces costs, improves quality and increases productivity by as much as 90%. We do not want any planning to interfere with our wrecking project. In order to interrupt the planning process, we can do a number of things that can be combined for maximum results:

• Do not assign anyone to the role of planning. Everyone will be so focused on fighting emergency breakdowns that virtually nothing will be planned. If you must have planners due to somebody meddling in your affairs, select inexperienced people to do the job, and personnel who have not earned the respect of their peers. Proactive organizations select planners who are the finest craftspeople, and are highly respected by their peers. You can’t have that.

• Make certain that anyone who is trying to plan is saddled up with as many distractions as possible. Make them chase parts for emergency work, have them supervise work, or even assign them to perform the repairs if you can! Planners are supposed to have their mind focused on the future, so distracting them with activities occurring in the present is a fantastic diversion.

• Set the expectations for planned work as low as you can. A well-planned job will completely destroy your efforts to wreck the maintenance program. We do not want job plans that contain detailed descriptions of the job, good estimates, clear instructions, drawings, digital photos, accurate parts lists and scheduled tasks. Encourage everyone to pencil-whip his or her plans, and just give a crude description of the job. A rotten, useless plan is even better than no plan at all, as it undermines the program, and makes people mad. You want that, right?

Tune in next week as we continue to expose the secret lives of seriously disturbed maintenance “professionals” with The Dirty Dozen Tip #6: Kill Off the Training Program & Other Excuses to Go to Florida.

“Tip” provided by NoBreakDowns.com
Tel: (218) 327-3114
http://www.NoBreakDowns.com

Receive a complimentary Dirty Dozen: 12 Ways to Wreck Your Maintenance Program electronic poster