Archive | June, 2004

275

2:21 am
June 2, 2004
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Online Maintenance Discussion Forums Offer Peer Advice

Unless you work in a maintenance department with a multi-location company, you are left to solve many day-to-day maintenance problems on your own, without much outside advice. You may be alone at your plant, but hundreds of other maintenance professionals have probably faced similar issues. Before the Internet, the knowledge and experience required to solve unique problems was locked in single locations, creating islands of expertise in problem solving.

Many maintenance-oriented Web sites offer some sort of message posting board or discussion forum that allows you to post a question, offer advice, or simply join in a lively discussion.

Discussion boards are usually divided into topics to make searching easier. When a person has a question or wants to share an expeorience, he simply enters information into a text box and then submits it. If the discussion group is not moderated, the message will appear on the Web instantly. If it requires moderation or approval from the administrator, there may be a slight delay. On the most popular message boards, replies, answers, and opinions appear almost instantly as well.

MaintenanceForums.com features three primary topics for discussion including reliability strategies, condition monitoring/PdM, and CMMS. The site does require registration to eliminate spam or commercial postings.

As you find topics you are interested in following, you can set e-mail alerts to notify you when someone posts a new message to that thread. You can get individual topic e-mail alerts in addition to daily or weekly digests of the entire online discussion. If you see a topic you think a friend would enjoy, you can even e-mail the entire thread.

The Society for Maintenance & Reliability Professionals (SMRP) offers a new discussion board for seven different reliability-related topics.

Snell Infrared offers online message boards for infrared thermographers at www.snellinfrared.com. These boards deal with one single condition monitoring technology but with that type of focus, you can usually find very detailed information. Another technology-specific discussion board is available from the Vibration Institute relating strictly to vibration analysis.

Root Cause Live is another discussion group with a focus on root cause analysis as does the Reliability Center.

For a broader selection of discussion forums, you can also search Yahoo Groups and Google Groups by topic or even by region for a more localized selection. There seems to be a group for just about anything you may be interested in on the Internet.

Many people prefer to “lurk” or simply read messages or discussions. Once you have an idea of how the group works, you should feel free to dive in and offer advice, ask a question, or simply state your opinion. Do not worry that your experience level is not as high as others involved in the group. Most of us still have a lot to learn and your post could make a huge difference to a maintenance professional. MT

Internet Tip: Save Web searches

Do you use the Internet for research, then cut and paste the items you find into MS Word or PowerPoint in order to share them with others?

You may want to try Onfolio to save and organize your Web searches and research into very nice reports you can publish and easily share with others through e-mail, documents, and the Web.The site offers a 30-day free trial.

Internet Tip: Distance Learning on the Web

As travel budgets tighten, maintenance and reliability professionals are finding new technology-based solutions for training and skills improvement.

Three new courses with maintenance and reliability topics are available online. VibrationSchool.com at has launched an Introduction to Vibration Analysis and LearnMaintenance.com at www.learnmaintenance.com offers basic maintenance skills training for hydraulics, pneumatics, and rigging. The University of Toledo is offering a Maintenance Management Certificate program .

Each of these courses uses a blended learning approach with a live instructor to coach students, some hard copy material (books and CD-ROMs), and Web-based information along with weekly assignments and e-mail roundtable discussions. Instructors are available by e-mail to answer specific questions and concerns from students. No travel is required to complete these courses.

These courses allow learning at each student’s preferred pace but must be completed within 12 weeks of the initial logon.

Distance learning courses will never replace live training, workshops, or courses; however, they provide a valuable alternative to those methods of learning.

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181

7:09 pm
June 1, 2004
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Credentialing Has Positive Implications for the Bottom Line

Training, then testing, reaps benefits for employees and companies.

Keeping up with the pace of continuously evolving technology is never easy, especially when it comes to automated manufacturing. Over the years, automation technology has grown increasingly sophisticated, helping to improve efficiency and maximize productivity.

On the flip side, however, such technological shifts also mean that engineers and technicians need to have the knowledge and skills necessary to design and maintain these sophisticated systems. The old adage “the best tools, when used by unskilled craftsmen, will still result in unsatisfactory results” continues to ring true, especially in the manufacturing environment.

More than ever, employees need to be equipped with the best tools and proper training to get the maximum benefit from an employer’s investment. In addition to the productivity benefits that come with a better-trained workforce, human resource executives know that employees trained to do their jobs become more engaged in their work.

Need skilled workforce
To successfully meet the demands of evolving technology, it is imperative that companies invest in the skilled people who design, program, maintain, and troubleshoot automation equipment. Ensuring a skilled workforce has become paramount to business success.

One of the wisest investments companies can make in their employees today is training. But, as many managers discover, simply attending training classes does not always ensure that the information presented is learned and, more importantly, applied. Many trainers and organizations have found that testing employees against a baseline can help determine areas where training is needed and can help to verify skills and knowledge.

Certification and its benefits
Certification provides companies a way to ensure skill levels at multiple sites, improving product quality through a highly skilled workforce. It also offers employees a way to benchmark skills and knowledge against industry standards and apply those skills to improve their work experience.

One organization that recognizes the growing need to find skilled workers is the Manufacturing Skill Standards Council (MSSC). Formed in 1998, MSSC (www.msscusa.org) is comprised of leading companies, international unions, educational and training organizations, and national, state, and regional government organizations focused on developing a national skill standards system for manufacturing. The MSSC system—skill standards, assessments, and certifications—is designed to give manufacturers a yardstick to measure, improve, and profit from a workforce trained in cutting-edge manufacturing skills.

All credible certification programs also require recertification. To ensure that certified professionals are knowledgeable on current technologies, some organizations simply verify that a professional is still active or experienced in the industry. Others require continuing education, rewarding of continuing education units (CEUs), and retesting at the end of a certain period.

Employees reap many benefits from these programs (see accompanying section “Employee Benefits from Credentialing”).

Certification as a change agent
Certification—whether on a product, technology, or process—can help organizations quickly implement new programs or changes. With manufacturing, testing, and assembly sites around the world, Intel Corp., Santa Clara, CA, is a leader in semiconductor manufacturing and technology.

Since 1998, Intel’s maintenance department has gradually embraced predictive maintenance as a key component of its machine uptime strategy. Using integrated condition monitoring tools from Rockwell Automation, Milwaukee, WI, Intel has designed and implemented a program that allows the company to effectively monitor, analyze, and track equipment performance—observing operating conditions locally as well as remotely—across multiple production sites.

As the program is rolled out across the organization, Mick Flanigan program champion, predictive maintenance program manager and project leader at Intel’s Northwest Regional Operations facility, uses training to build program consistency at each of the sites. Using a customized vibration training course he developed, technicians at each site are introduced to the basics of vibration monitoring, data collection, and the Entek Enshare software.

As individuals begin taking more active roles in the analysis and reporting of data, Intel enrolls them in advanced vibration analysis training. At the close of each training session, the Intel employees take a written certification exam that covers the material presented during the 3-day training session.

“For Intel, vibration analysis training and certification has become a valuable tool,” Flanigan said. “In addition to helping build and maintain a knowledgeable maintenance team, it also helps the maintenance department build management’s confidence in the program.”

Through its vibration analysis training and certification program, Intel has been able to develop and implement a consistent predictive maintenance program at 14 of its 19 global production sites, including facilities in the U.S. and in China, Costa Rica, Ireland, Malaysia, and the Philippines.

Certification means credentialing
Certification signifies that professionals have learned and mastered a specific product or technology. These professional credentialing programs establish competency standards for a given job.

Similar to the CPA exam in the accounting industry, which sets professional standards and performance requirements, credentialing in the manufacturing environment results in more qualified engineers, technicians, and operators on the plant floor. Organizations such as the Society for Maintenance & Reliability Professionals Certifying Organization (SMRPCO) aim at raising the visibility and professionalism of the maintenance function as a whole (www.smrpco.org).

Organizations credential individuals in a variety of ways, but almost all of them require some level of testing, including written and practical exams. Some organizations also require a documented minimum amount of experience in the industry or minimum educational requirements.

A more engaged workforce
Credentialing provides an objective, outside look at what professionals should know when applying a given technology. Professionals who participate in a credentialing program have a clearer understanding of their skills and abilities compared to industry requirements, which can help them better focus development efforts to create and maintain the most comprehensive skill set for their industry.

Credentialing programs also can encourage ongoing learning. Continued education introduces employees to new technologies and practices that they can apply to their own facility or operation.

Many companies today already offer incentives for their employees to participate in credentialing programs. With programs available from all major producers of automation controls equipment, finding the credentialing program that best fits with a particular operation or company is simply a matter of selecting the program most appropriate for the manufacturer’s installed equipment base. Some companies today also encourage their employees to be certified in multiple technologies.

Heightened respect and awareness
For manufacturers, credentialing can provide an impartial measurement of the company’s capabilities. The number of credentialed employees, for example, can send a message to shareholders and customers alike that a company’s employees are more qualified to do their jobs and are better prepared to respond to changes in the industry or marketplace.

Not too far in the future, information such as the number of certified employees will likely be used as a competitive measure between companies. Two systems designers bidding on the same project, for example, might find that the key differentiator between winning and losing a bid lies in the qualified staff who will ultimately work on the project.

Winner takes all
The bottom line is simple: certification improves productivity and efficiency for manufacturers and system designers. By adopting new standards and offering appropriate training programs, automation equipment manufacturers and industry trade associations can set the industry benchmark for required levels of skills and knowledge.

Increasingly, certification and credentialing are being viewed as a mark of distinction for employees who demonstrate their commitment to their profession. These programs offer significant professional and competitive advantage to companies and employees, allowing them to demonstrate that their skills and knowledge are the best. MT


Laurie Moormann is the director of the Training and Performance Services business unit at Rockwell Automation, 6680 Beta Dr., Mayfield Village, OH 44143

Employee Benefits from Credentialing

Employees reap many benefits from credentialing programs, including:
• Clearer direction for career development and education
• Recognition within their current organization
• Better pay
• Greater transportability of skills between plants and companies
• Advantages in job promotion
• Greater job effectiveness
• Improved ability to differentiate between candidates in the hiring and
promotion process
• Improved training effectiveness

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189

7:07 pm
June 1, 2004
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Blended Learning Solution Aids Companies

Web-based courses, hands-on evaluations score with employees and employers.

Many industrial facilities are challenged with recruiting and retaining an adequate supply of trained maintenance technicians. Most of the people who possess the required skills already have positions. Younger people just coming out of school generally do not seek careers in this field.

Now some of these companies have turned to a new hybrid solution to train technicians that combines the efficiency and economy of online delivery with the practicality of hands-on performance evaluations.

Classroom training difficult
The answer to a skills shortage may appear deceptively simple: industrial companies could both train new technicians internally and upgrade the skills of those they currently employ. But many organizations have encountered an additional obstacle: when and how to provide the training. Until recently most have relied on after-hours classroom training, an approach that has met predictable resistance.

One such company is Fluor Corp., one of the world’s largest engineering, construction, and maintenance services organizations. Jim Maxon, senior manager of the Maintenance Technician Training Program for Fluor’s Operations and Maintenance Unit, found offering classes after regular working hours did not meet the needs of the workforce.

“Many Fluor technicians work 10-hour work days and multiple shifts,” he said. “To ask technicians to stay after work on their own time for an hour-and-a-half to two hours to attend a course is too much for the typical family-type person.”

Web option considered
One solution to this training dilemma is Web-delivered training. It provides the kind of scheduling flexibility that employees want. However, many managers have remained unconvinced of its value for the kinds of hands-on skills that maintenance technicians require.

Online training may effectively teach concepts and cognitive skills, skeptics argue, but then you have people who know concepts but have not had to demonstrate practical skills.

Fluor originally planned to use CD-ROM-based courses for technician training. The company began a pilot project but soon discovered that it would cost in excess of $100,000 per site to purchase the necessary licenses. Since Fluor trains technicians at multiple locations, the price tag far exceeded what the company wanted to spend.

Fluor approached training vendor PRIMEDIA Workplace Learning about converting the costly CD-ROM courses into Web-delivered ones. The company agreed but decided to go further to meet the specialized demands of maintenance training. That program has now become what PRIMEDIA calls PRIMEed.

New multi-pronged approach
The program takes a multi-pronged approach to training maintenance technicians that combines competency evaluations, a library of 75 Web-delivered courses, and hands-on performance evaluations.

“We created this program to meet the needs of industrial customers who want flexible training for their employees and who also want their employees to be able to quickly apply that knowledge on the plant floor,” explained William R. Joiner, vice president and general manager of PRIMEDIA’s Industrial Services Group. “The addition of hands-on performance evaluations to our online offerings gives companies a blended solution that combines the advantages of both training methods.”

The program’s approach affords industrial companies some distinct benefits. The competency evaluations, delivered online, help companies identify knowledge gaps and deliver only the training each technician needs.

Another advantage comes from Web-delivery of course material, which enables employees to take the courses on their own schedule and at their pace while helping companies minimize employee downtime. However, it is the hands-on element that has made the difference for companies such as Fluor.

After employees complete a course online, they are given a hands-on performance evaluation. These evaluations can be administered by subject matter experts at a company’s facility or at a local community college that offers the program. Performance evaluations not only ensure that employees retain what they learned online but also require them to demonstrate that they can apply those skills on the plant floor.

Fluor uses its own certified instructors to verify that employees can perform the hands-on requirements for a particular course. The company certified over 100 evaluators at its multiple locations through the National Center for Construction, Education, and Research (NCCER).

College involvement
Other companies have chosen to work with community or technical colleges to administer the program and provide instructors and lab facilities for the hands-on evaluations. For example, Greenville Technical College, along with the 15 other schools in the South Carolina Technical College System, offers the training program as part of its continuing education curriculum.

Ned Horton, director of occupational and industrial relations at Greenville Tech, likes the program because his school can tailor it to meet the specific needs of companies in its service area.

“One company may have three different courses they want their people to go through,” he said. “In the past, it was one size fits all, but now we have a tremendous amount of flexibility in customizing the program to meet the needs of individual customers and their employees.”

Some hands-on evaluations run 4 hours while others may last only an hour. Greenville Tech sets its labs up in 8-hr blocks so it can include several different sessions in one day, which accommodates companies that prefer to have employees report to the college for an entire work day and cover as much material as they can rather than have them attend several short sessions.

This blended approach also overcomes the problem of students who struggle with the content but want to complete the courses. “They can take one hour to go through a Pneumatics I course, or they can take as long as they need,” Joiner said. “They can go through it over and over again until they get it without being rushed or embarrassed because they didn’t get it the first time.” In fact, if employees encounter difficulty during a hands-on performance evaluation, they can review the course materials and try again.

System manages training
Another component of the training program is the learning management system (LMS) that the company developed specifically for the new program. The LMS has automated all steps of the process, from scoring the results of an initial competency evaluation to enrolling students in specific courses and scheduling them for the accompanying hands-on performance evaluations.

According to Keith Carpenter, director of national accounts for PRIMEDIA, the company designed the LMS so that “the individual’s customized status page shows them exactly where they are within each training track. The LMS also forms the entry point where employees can simply click on the courses or tests to take.”

Once an employee in the program has met all the prerequisites—the courses they must pass as determined by the initial competency evaluation—the LMS automatically provides them with the schedule for the hands-on evaluation. Employees can enroll in the hands-on evaluation only after they have mastered the theory behind each skill.

In regard to the LMS, Maxon said, “We track and maintain all records of the Maintenance Technician Training Program within the database with no required data entry. To date we have administered over 10,000 tests, all of which have been scored electronically within the LMS. Our workforce development coordinators are able to access all this information easily through a user-friendly format. It is a pretty remarkable tool that is saving Fluor thousands of dollars each year in testing administration.”

Fluor is committed to the program and is delivering it to far-flung areas, so these Web-based delivery and tracking capabilities are critical. Maxon recently demonstrated the courses to a group in Shanghai, China. He has also done demonstrations for groups in Manila, Korea, and Australia.

Fluor’s operations and maintenance management has been pleased with the results to date relative to the number of courses successfully completed, the number of Fluor certifications issued, and the “repeat business” of the technicians. This “repeat business,” Maxon explains, “speaks volumes about the overall system and approach to training being deployed.” MT


Michael Welber is a freelance writer based in the Florida Keys who has written on a wide variety of subjects including e-learning, training, sales training, tourism, and other business topics. More information is available through PRIMEDIA Workplace Learning, 4101 International Pkwy., Carrollton, TX 75007; telephone (800) 848-1717

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1455

6:36 pm
June 1, 2004
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Reduce Downtime with Smart Scheduling

By taking a few extra administrative steps, maintenance managers can implement more preventive maintenance in less time.

For years, maintenance managers have successfully been using enterprise asset management (EAM) or computerized maintenance management system (CMMS) software to decrease unscheduled downtime. But managers whose plants are running at maximum capacity face the classic struggle between maintenance and production. One department needs to idle the equipment for preventive maintenance (PM) to avoid unscheduled downtime while the other must have unbroken uptime to meet its production quota cost.

Maintenance managers can help ease this tug of war by implementing a straightforward approach called Smart Scheduling. Smart Scheduling can reduce planned downtime by as much as 50 percent, making it easier to wedge maintenance into a busy schedule and provide efficiencies that lead to documented cost savings.

Coordinate activities
Smart Scheduling means coordinating all PM activities for related assets, then using an EAM’s scheduling capabilities to plan ahead and “gang up” maintenance events, ensuring that all necessary resources and materials are available for the time that the equipment is scheduled to be out of service. This will maximize efficiency and minimize downtime. Most EAM software packages can help do this, but some newer programs have features to simplify the process.

For example, in two days a plant is scheduled to complete an annual PM activity on machine A, a key piece of equipment. To complete the PM activity, related equipment must be taken down, including machines B and C for an hour or so, which probably will upset the production manager.

To lessen the blow, the EAM can be used to look a month or two into the future to see if there are any additional PM activities coming up for machines A, B, and C. As it turns out, B and C are due for a monthly PM activity next week, and a semi-annual activity is scheduled for A the following week. Now all four can be done at the same time, minimizing downtime, increasing efficiency, and reducing costs. Or if machine C has a yearly PM activity coming up in two weeks, as long as it is down for the monthly, the yearly can be done at the same time.

Implementing the program
Reaping the benefits of Smart Scheduling can require some extra planning and decision-making. Following are a few highlights of some of the steps involved in implementing a Smart Scheduling program.

Identify common procedures and tasks. Begin the process by fully identifying common procedures, making sure to include all estimated parts, labor, and tools. List labor by craft; determine the PM schedule. Start by reviewing the manufacturer’s recommendations then temper that with experience.

For example, if an uncommon number of breakdowns occur between scheduled maintenance events, plan to schedule events more frequently. Conversely, if following the manufacturer’s recommendations leads to unnecessary maintenance, adjust the frequency based on the experience with the facility’s operating environment.

Write tasks and procedures to cover the required PM. To make sure all the exact resources required to do one particular job are available, duplicate or copy the procedure using those functions in the EAM software. Change items that may not be applicable to the equipment being serviced. With these changes, the procedure is unique to that piece of equipment but the procedure/task list is kept consistent and concise.

If the duplicate and copy links functions are not available in the EAM package, write a generic procedure that can be used repeatedly. Remember to make the tasks applicable to all similar equipment and customize procedures by calling out the appropriate tasks, parts, tools, and craft labor.

Determine a scheduling method. The scheduling function of most software programs gives three choices: “since last completed,” “since last scheduled,” and a metered system based on equipment run time or a calendar.

With the “since last completed” option, if the PM activity is originally scheduled on May 7 but is not completed until May 30, the PM will adjust the schedule to set the next due date on April 30. This can increase efficiency because things are being done only as needed.

Over time, the “since last completed” approach yields an advantage, as it will distribute workloads and schedule tasks based on documented evidence of what you can accomplish in one given period.

The “since last completed” option also has its disadvantages, depending on the EAM software. Older EAM systems usually do not ensure that monthly, quarterly, semi-annual, and annual PM activities come due at the same time. If the monthly activity is done but not the quarterly, it is possible to throw the entire system off track and lose any coordination that may have been established between maintenance activities.

“Since last scheduled” means that the activity is done every 30 days on the seventh of the month, for example. One benefit is that a paper trail is maintained. This method will ensure schedule documentation. But a bigger advantage is that this method will maintain the synchronization between maintenance activities that have varying frequency.

There is also a downside. If a monthly PM activity is scheduled for today but does not get completed until the end of the month, the EAM system will prompt to do it again one week later, which is not necessary.

Metering is the most efficient system. It makes sense to take this approach with PM scheduling. If there is some type of meter on some piece of equipment, that meter can be used to set PM intervals. If the operation is running 24/7, important PM activities may come due in a period of 20 days instead of 30. Conversely, if orders are down and production is running slowly, maintenance events may be able to wait 45 days. This approach is especially useful in scheduling seasonal equipment or any machinery that is operated intermittently.

This method is not limited to hour meters. It can be used with almost anything that can be counted, like the number of boxes that are packed out at the end of the assembly line, the number of parts, or the number of cycles or strokes the machine makes. One meter, at the end of an assembly line, for example, can be used to schedule the maintenance of a whole group of related equipment.

Regardless of the method used, determine the capabilities of the EAM software before making a decision. The scheduling module can be used to look into the future to make sure that everything comes out together.

Schedule different maintenance activities to occur in the same downtime period. To bring PM activities together into the same downtime period, identify when actions are coming due, ensure that schedules are synchronized, and audit procedures to make sure each action is accomplished.

Start by identifying when actions are coming due. Look further into the future—perhaps a calendar quarter, but at least a month. As previously mentioned, if the annual PM is also going to be due within the next couple of weeks, consider scheduling the annual event for the same time the monthly and quarterly events are scheduled.

Communicate the needed downtime to those responsible for operating the equipment so they will not have people idle while the machinery is out of service. Plan ahead and arrange to have all necessary parts, permits, tools, and labor available before the equipment is to be taken out of service.

Make sure schedules stay synchronized, whether using “since last completed,” “since last scheduled,” or a metered system. If they are out of sync, adjust scheduled events to put the entire system back into synchronization.

Finally, audit procedures to make sure they are accomplished as scheduled. Compare estimated labor times to actual times, and update all estimates. Examine actual parts use and correct the procedures to call for the right parts in the correct quantities. Check actual downtime against estimated downtime so that the new data will help to estimate production downtimes in the future. Also, be sure to solicit feedback from the people who actually have their hands on the equipment, then update the PM procedures using what is learned.

Once a system is in place, never stop looking for ways to improve or modify it. Smart Scheduling involves a little more administrative work, but it is well worth the effort. MT


Leland Parker is a senior consultant for DPSI, 4905 Koger Blvd., Suite 101, Greensboro, NC; (931) 537-7424

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206

5:43 pm
June 1, 2004
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Educating the Executives–And Yourself

wireman

Terry Wireman, C.P.M.M., Editorial Director

There was considerable information presented at the Maintenance & Reliability Technology Summit (MARTS) last month about all aspects of maintenance and reliability. The presentations were content laden with many case studies and workshops. However, one question was frequently asked: “How do I get my senior managers to an event like this?”

This is a question that is asked all too often. Maintenance and reliability managers are always seeking better methods of communicating the value of their organizations to their peer groups and senior management. Can this actually be accomplished, and how do maintenance and reliability managers get started?

The first step for the maintenance and reliability manager is self-education. This will involve selected reading of the many books that are currently available. It also includes reading the latest maintenance and reliability-focused magazines, joining appropriate technical societies (AFE, SMRP), and additional Internet research (www.reliabilityweb.com, www.mt-online.com). If the budget exists, it also should involve attending selected maintenance and reliability- focused conferences and workshops.

The question could be asked, “Why go to all of that work? After all, I still have a department to run.” The answer is that to be an educator; you first have to be educated. While there are many maintenance and reliability managers who understand and can communicate the technical aspects of their business, how many understand how to sell the business benefits (particularly the financial aspect) of their maintenance and reliability organizations? That is the purpose of all the self-education.

Successfully managed organizations take a business focus with maintenance and reliability. It is common to hear or read about return on investment, financial justification, and business analysis when case studies are presented. Why? The financial focus is the only way to win and maintain executive sponsorship for maintenance and reliability improvement.

With this in mind, how do maintenance and reliability managers get their senior executives to attend conferences or read articles about maintenance and reliability? It might be beneficial to review the presentations at a particular conference before attending. Are your competitors presenting? Almost every senior executive wants to hear what his competitors are doing. Are there presenters from a similar industry? Are any of the presenters discussing how they solved a problem that your company is currently struggling with? A maintenance and reliability manager could ask the same questions for magazine articles or books he is contemplating reading and sharing with senior executives or peers.

Once the senior executives have started reading articles or decided to attend a conference, ensure they stay focused. Don’t force them to read or hear “nice to know” material, but rather the “need to know” material. Make sure they understand the application of the information to your plant situation or problem. If they don’t appear to understand the information, take the time to clarify it and make specific application of the points you want them to remember.

If the senior executives are attending a conference and some of their peers are there, ensure that they meet and have an opportunity to converse. You will occasionally find an executive who will regularly attend maintenance and reliability conferences. It has tremendous impact when your senior executives hear one of their peers endorse concepts that you have been trying to get approval to implement. Even if none of their peers are at the conference, make sure they meet some of the presenters. The presenters will likely have information from their plants that they have shared with their senior executives that was not included in the presentation.

Since there are few MBA, PhD, or other degree programs that require courses in maintenance or reliability, it is up to existing maintenance and reliability managers to fill this gap in their senior executives’ education. If you are currently having a problem obtaining senior management approval for your maintenance and reliability initiatives, try some of these suggestions. You will not get too many chances to obtain their support; make the most of the ones you have.

If you do succeed, keep good documentation. You may be writing an article or giving a conference presentation in the future that will help someone else improve their maintenance and reliability practices. You know they will appreciate it. MT
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199

5:41 pm
June 1, 2004
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Responsible Leadership

bob_baldwin

Robert C. Baldwin, CMRP, Editor

During a recent visit to the U.S. Postal Service’s Maintenance Technical Support Center, I saw a copy of the “Leadership Principles of Colin Powell” framed and hanging on the wall. As I passed, I caught a glimpse of his first lesson: “Being responsible sometimes means pissing people off.”

Intrigued, I Googled the title when I got home and found a PowerPoint presentation of Powell’s principles on the Web and found out there is also a book by that title.

Three of the 18 principles, or lessons, have special relevance to maintenance managers searching for that silver bullet or special program that will solve their problem of doing more with fewer people and less money. Here they are.

Lesson 3: Don’t be buffaloed by experts and elites. Experts often possess more data than judgment. Elites can become so inbred that they produce hemophiliacs who bleed to death as soon as they are nicked by the real world.

Powell notes that smaller organizations don’t have the money to subsidize lofty elites so everyone on the payroll visibly produces and contributes to bottom-line results or they’re history. But as they get bigger, they often forget who brought them to the dance: things like all-hands involvement, egalitarianism, informality, market intimacy, daring, risk, speed, agility.

Lesson 4: Don’t be afraid to challenge the pros, even in their own backyard.

Learn from the pros, observe them, seek them out as mentors and partners. But, Powell cautions, remember that even the pros may have leveled out in terms of their learning and skills. Sometimes even the pros can become complacent and lazy.

Lesson 11: Fit no stereotypes. Don’t chase the latest management fads. The situation dictates which approach best accomplishes the team’s mission.

Flitting from fad to fad creates team confusion, reduces the leader’s credibility, and drains organizational coffers. Blindly following a particular fad, Powell says, generates rigidity in thought and action. Sometimes speed to market is more important than total quality. Sometimes an unapologetic directive is more appropriate than participatory discussion. Some situations require the leader to hover closely; others require long, loose leashes. Leaders honor their core values, but they are flexible in how they execute them. They understand that management techniques are not magic mantras but simply tools to be reached for at the right time.

Then, Powell lays it on with his definition of leadership.

Leadership is the art of accomplishing more than the science of management says is possible. MT

rcb

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278

4:16 pm
June 1, 2004
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Optimize Maintenance/Asset Management Policies

Translate contributions into the language of finance.

In the majority of companies today, there is a language barrier. There are at least three different languages spoken internally—financial, operational, and technical.

Just as language can be a barrier in communication with others on a personal level, the different languages spoken in a company also create barriers. For example, operational personnel have difficulty understanding issues faced by the maintenance and engineering departments since they are always expressed in terms such as life cycle costing, mean time between failure, or mean time to repair. Maintenance and engineering personnel may have difficulty understanding cost per unit, return on cost of capital, or total cost to produce.

Language of finance
Ultimately, the one language that must be understood throughout the company is financial. Regardless of the decision being made, the ultimate factor will be expressed in the language of finance. This requires that all other departmental languages translate their contributions into financial terms. However, can this actually be done? Can the maintenance and engineering functions clearly articulate their impact on the financial standing of the company?

Nearly all maintenance and engineering decisions are cost benefit or return on investment decisions. This means that all decisions that involve maintenance should be considered in the light of the financial impact on the company. The maintenance or engineering perspective is typically expressed in extended useful life of assets, increased throughput or availability, or improved product or service quality. Clearly the problem for maintenance and engineering is how to convert these benefits into financial terms so the entire organization can quantify them.

Maintenance impact costs
The majority of maintenance and engineering decisions impact at least five major cost categories:
• Labor
• Material
• Overhead
• Function loss
• Function reduction

Labor costs are the expenses for having maintenance technicians on staff. This will include all related expenses including overtime, benefits, etc. Each job will have the cost of the number of employees times their hourly rate plus any incentives. This cost makes up approximately 50 percent of all direct maintenance expenditures.

The material costs include all parts and equipment replacement expenses controlled by maintenance. The costs of all parts or equipment components used on a job should be tracked through the work order system. Material costs make up the other 50 percent of all direct maintenance expenditures. It should be noted that if maintenance contractors are used in a company, their costs are divided similarly.

Overhead costs include clerical and staff support for maintenance. Typical overhead costs are about 15-25 percent of the usual maintenance labor costs.

The function loss (also known as equipment breakdowns) costs are the hidden or difficult costs to ascertain. Studies have shown that these costs will range from 2:1 to as high as 15:1 per maintenance activity. So when a maintenance task costs $10,000 in labor and materials, function loss costs could run the true total costs of the incident to as high as $30,000-$160,000. This makes a tremendous difference in looking at the cost of a maintenance action.

In addition, there are also function reduction (also known as efficiency losses) costs. In some organizations, these are also known as idling or minor stoppage losses. These occur when the equipment operates, but has intermittent problems that are typically not significant enough to count as a function loss (breakdown) but have a significant impact on the efficiency of the equipment. Studies by Japanese companies have shown that these types of losses always exceed the losses incurred in function loss or equipment breakdowns, sometimes by as much as four times.

The restoration of a function loss breakdown will usually involve some cleaning or replacement of a component on a trend of decreasing efficiency. This could be tasks like cleaning pumps with decreasing efficiency or restoring the full operational capacity to production equipment. This is an overlooked area of maintenance improvement.

Compliance with governmental regulations also can be a function of maintenance. For example, one municipality was fined over $1 million for an environmental violation. The cause of the violation was ultimately traced to a pump that was improperly maintained. Fines are a small part of the total picture when damage to the environment or employees’ health or damage due to improper handling of hazardous materials is included.

Collect the information
It is necessary to put the costs vs benefit discussion in a form that all departments in the company can understand. Figure 1 shows this material in a graphic form, revealing that the decision for maintenance would be made based not on what is best for the operations group, nor on what is best for the maintenance group, but on what is the lowest combined cost. This is the effective “bottom line” for the company and its shareholders. This is the type of decision that companies must make if they are to optimize their resources.

How does a company go about collecting the information required to perform this analysis? It starts with assigning a cost to downtime or unavailability. It may be useful to use the financial or accounting departments to find out what an hour or a shift of lost production is worth for a piece of equipment. This might include lost sales, employee salaries and overhead, the cost to make up lost production (if it can be made up), and any measurable depreciation to the assets. The figures coming from the financial department will usually be conservative, but will not be disputed by other parts of the organization.

With these figures agreed to, it is necessary to understand the maintenance costs involved. This may include the labor, material, or supply and miscellaneous costs that will be incurred due to the repair or the failure. These costs may be needed to compare an overhaul to a run to failure approach to maintenance. Additional costs that may be incurred also should be calculated including hazardous materials, Environmental Protection Agency, Occupational Safety and Health Administration, or safety considerations.

Once the total cost is understood, companies can identify some interesting problems and use this technique to justify and solve them. We will address scenarios in three main areas:
• Preventive maintenance (PM) frequencies
• Critical spares analysis
• Normal maintenance parts and supplies

PM frequencies
To examine PM frequencies, let’s look at a piece of equipment common to most plants or facilities—a centrifugal pump. It may be pumping a product or moving cooling water. The point is it will have a value to its service. Setting a price on the value gives a reference from which to start. If the value is $100 per hour, then this allows managers to solve the following problem:

History shows it cost $1500 for parts and labor to overhaul the pump. There is no downtime cost since there is a standby pump available. The pump performance is measured, and it is found that after 4000 hours of operation, it loses 5 percent of its capacity. In order to simplify the problem, it will be assumed that the drop is linear and continues to be so throughout the life of the pump. When is it cost effective to remove the pump from service and clean the rotor?

The problem is solved by calculating the amount of maintenance cost vs lost performance cost per hour. The two are combined to give the lowest total cost. The techniques to perform this analysis are illustrated in Fig. 2, 3, 4, and 5. In Fig. 2 the maintenance cost is calculated. The mistake of considering only maintenance costs is highlighted in this particular example. If only the maintenance costs were considered, it would be advisable to delay servicing the pump for as long as possible.

The point in Fig. 3 is that if you delay the service, the amount of lost production cost is increasing linearly. However, the difference between Fig. 3 and Fig. 4 is that the latter takes into consideration that the performance fall off is triangular and not the total area volume of the rectangle.

The summary of the problem is in Fig. 5. It plots the falling maintenance cost against the increasing cost of lost performance. These two factors added together will give the total of the true costs. The decision can then be made on lowest true cost, which in this problem would indicate the maintenance action should be performed every 1500 hours of actual run time.

The problem can become more complex, since this example has no penalty cost for the downtime required for the maintenance action. If it would cost additional money for the downtime, then this column would have to be added. However, in the example just given, the only downtime that would likely be incurred is when the repair was made. Some problems will include breakdowns when maintenance intervals exceed a certain level. This means that downtime may have to be factored in during the cycle. This will radically alter the results of the calculation.

For example, continuing to expand the problem in Fig. 5, the downtime costs could be added with the result being Fig. 6. Now the downtime drives the true cost even higher than it was previously. However, in this example, the initial cost of the downtime is factored in immediately. The breakdown will occur only if maintenance is not performed before 3000 hours of operation. If the maintenance frequency extends beyond that time, an additional cost of $2400 (24 hr x $100/hr value of the process) will be incurred. This removes any doubt that the lowest total cost would be around 2000 hours of operation, but definitely before 3000 hours of operation.

Useful statistical techniques
The ability to apply statistical techniques can go far beyond the simple example used in this article. Consider the ability to perform this type of costing for each subcomponent of a large mechanical drive; the ability to determine the lowest life cycle costing for complex equipment; the ability to determine the amount of resources to be spent on redesign and retrofit engineering projects, based on anticipated return on investment.

However, while this is a straightforward mathematical model, why are there so few companies doing this type of calculations? It is because few of them have any reliable data with which to work. This clearly highlights the necessity to have a good computerized maintenance management/enterprise asset management (CMMS/EAM) system in place with accurate historical records. The data to perform these calculations must come from the work order system. Without this reliable data, companies will be back to guessing when maintenance activities should take place and not financially justifying the maintenance activity.

Critical spares analysis
A second example of statistical financial controls examines critical maintenance spares. Spare parts are an albatross for maintenance managers. Operations and upper management see critical spares (which are typically slow moving) as unnecessary since they never seem to turn over. The same techniques can be applied to the spares as was applied to the equipment. For example, consider what costs must go into a stocking decision:
• How many are used per year or mean time between failures?
• What are the operating requirements for the equipment per year?
• What is the cost of downtime if the part is unavailable?
• What is the annual holding cost for the item?
• What does the item cost?
• How often can the item be repaired?
• What is the lead time to get a replacement?
• What is the lead time to repair the item?

After the costs related to the stocking decision are all identified, then a logical decision can be made concerning the stocking level. For example, the difference between keeping no spares and keeping one spare could be substantial when resulting downtime is factored in. Typically critical spares have long lead times. If no spares are kept, the resulting downtime may be weeks of lost production. This can quickly add up to tens of thousands of dollars. Consider the example of a gearcase costing $24,500 that is a spare on one equipment unit.

When the gearcase is ordered, it takes 1 week to receive the spare. The holding cost is 30 percent of the price of the gearcase. While it is down, the downtime cost is $1000/hr. When it is replaced, the actual time to replace is 40 hours and the labor cost is $1000. Currently there are four spares stocked and annual usage for the past 3 years shows that one gearcase was changed each year. Based on this information, how many spares should be stocked and why?

Keeping in mind the total cost curve, you must plot the cost of investment (stocking the part) vs the cost of downtime during a failure. This can be performed in a table format or in a graph format (Fig. 7).

When the comparison is made, it is clearly seen that keeping one spare is the optimum financial decision for the company. The difference between keeping one spare (optimum) and keeping four spares (current policy) is $95,700. This is considerable savings on just one spare. Most companies have hundreds of these types of spares. Consider the savings possibilities for optimizing critical spares.

Also consider the saving potential for an organization that reduces inventory without factoring in the cost of downtime. The difference between keeping none and keeping one is $136,100. This is an even more dramatic savings. It is only when companies take this financial approach to maintenance spares stocking that inventories will truly be optimized. This is a stiff penalty to pay for short-sighted decisions.

Normal maintenance parts, supplies
The same calculations could be applied to normal stores items. If the same information is kept, statistical formulas can be used to calculate service levels, actual cost per item, number of projected turns per year, etc. These can provide a manager with the tools necessary to make accurate and cost-effective management decisions.

The drawback to all of the calculations is the need for accurate data. This is why the entire organization must have the discipline to collect accurate data before any of the techniques in this article can be utilized. Using statistical techniques with poor or inaccurate data will provide no more accurate an answer than guessing at it. A good, disciplined approach to a CMMS/EAM system will enable many of the techniques shown here to be useful to a company attempting to optimize its total asset costs.

The language of finance must always be the internal language spoken in companies today. While there may be other languages (technical, operational, etc.), ultimately the owners or shareholders want to see clear financial statements. It is only by an entire organization learning to speak the financial language that this requirement will be met. MT


Terry Wireman is senior industry analyst at GenesisSolutions, 100 Danbury Rd., Ste. 105, Ridgefield, CT 06877; (203) 431-0281

COST EFFECTIVE MAINTENANCE

0604wiremanfig1

Fig. 1. Decisions that involve maintenance should be based not on what is best for the operations group or
for the maintenance group, but on what is the lowest combined cost. This is the effective “bottom line” for the company.

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Fig. 2. Basic Maintenance Cost Calculation

Repair cost = $1500
If the pump was serviced once every 100 hours, the cost would be $1500/100 = $15/hr
If the pump was serviced once every 500 hours, the cost would be $1500/500 = $3/hr

Service Frequency (hrs)

Maintenance Cost ($)

100

15.00

500

3.00

1000

1.50

1500

1.00

2000

0.75

2500

0.60

3000

0.50

3500

0.43

4000

0.38

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Fig. 3. Lost Performance Calculation

If the performance loss is linear, then at 4000 hours of operation, the loss is 5 percent. If the value is $100, then the value of the loss is: 0.05 x $100/hr = $5/hr
Therefore, at 4000 hours of operation, the pump is producing a value of only $95, or it is losing $5 per hour

Time Since Last Service (hrs)

Lost Performance Cost ($)

100

0.13

500

0.63

1000

1.25

1500

1.88

2000

2.50

2500

3.12

3000

3.74

3500

4.36

4000

5.00

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Fig. 4. True Lost Performance Calculation

The true lost performance cost is usually calculated by a calculus formula. However, a simple geometry formula can serve the purpose in this simple example.

The total loss is not the entire rectangle, but only one-half of its area. So the loss would be only one-half of the calculated amount. The revised version of the table would be:

0604wiremanfig4

Time Since Last Service (hrs)

Lost Performance Cost ($)

100

0.065

500

0.31

1000

0.63

1500

0.94

2000

1.25

2500

1.56

3000

1.87

3500

2.18

4000

2.50

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Fig. 5. True Total Cost Calculation

The true total cost now can be established for this task. Combining the tables in Fig. 2 and Fig. 4 results in:

Time Since Last Service (hrs)

Maintenance Cost ($)

Lost Performance Cost ($)

True Total Cost ($)

100

15.00

0.065

15.065

500

3.00

0.31

3.31

1000

1.50

0.63

2.13

1500

1.00

0.94

1.94

2000

0.75

1.25

2.00

2500

0.60

1.56

2.16

3000

0.50

1.87

2.37

3500

0.43

2.18

2.61

4000

0.38

2.50

2.8

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Fig. 6. Factoring in Breakdown Costs

If a breakdown occurs and there is no spare, then the service also results in a cost penalty to the Operations Group:
• For planned service, 8 hr of downtime
• If a breakdown occurs, 24 hr of downtime
A breakdown will occur every 3000 hours of operation, based on repair records. The table shows

Time Since Last Service (hrs)

Maintenance Cost ($)

Lost Performance Cost ($)

Downtime Cost ($)

True Total Costs ($)

100

15.00

0.065

8.00

23.07

500

3.00

0.31

1.60

4.91

1000

1.50

0.63

0.80

2.93

1500

1.00

0.94

0.53

2.47

2000

0.75

1.25

0.40

2.40

2500

0.60

1.56

0.32

2.48

3000

0.50

1.87

1.07

3.44

3500

0.43

2.18

0.91

3.52

4000

0.38

2.50

0.80

3.68

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Cost of Critical Spares

Project Results

 

Total Cost

Impact Costs

Purchasing & Holding Costs

0

$209,000.00

$209,000.00

None

1

$  72,900.00

$  41,000.00

$  31,900.00

2

$104,800.00

$  41,000.00

$  63,800.00

3

$136,700.00

$  41,000.00

$  95,700.00

4

$168,600.00

$  41,000.00

$127,600.00

5

$200,500.00

$  41,000.00

$159,500.00

6

$232,400.00

$  41,000.00

$191,400.00

7

$264,300.00

$  41,000.00

$223,300.00

8

$296,200.00

$  41,000.00

$255,200.00

9

$328,100.00

$  41,000.00

$287,100.00

10

$360,000.00

$  41,000.00

$319,000.00

0604wiremanfig7

Fig. 7. After the costs related to a critical spares stocking situation are all identified, then a decision can be made
concerning the stocking level. Companies should plot the cost of investment vs the cost of downtim
during a failure in either a table format (above) or a graph format (below).

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2:32 pm
June 1, 2004
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Taking Accurate Vibration Measurements

Have you ever talked to a vibration technician who is upset because vibration readings from a new data collector are different from those of an older unit or different brand? On the surface it seems logical that they should agree. An overall velocity reading is an overall velocity reading, right? Not so fast.

Filter settings, frequency ranges, overall calculation from a spectrum, and accelerometer ranges are just a few of the factors that can influence the apparent amplitude of a measurement.

As an example, a customer at a large oil refinery was concerned that his recently purchased cooling tower monitor indicated 25 mils of vibration at the output shaft. The monitor card was designed to display the correct amplitude for the 67 rpm fan. Two other portable systems indicated 8 and 10 mils of vibration using the same permanently mounted velocity transducer.

Some investigation showed that when the portable instruments integrated to displacement, they were not linear at the 67 rpm fan speed. The manufacturers of the portable instruments provided multipliers to apply to the measurements and all was well. The adjusted portable instruments’ measurements were within 2 to 3 mils of the monitor’s readout.

Overall measurement filter settings
Many vibration instrument manufacturers use a spectrum to calculate the “overall” reading such as velocity. For example, if a spectrum is set from 0-24,000 cycles/min (cpm) or 0-13 orders on an 1800 rpm machine, the overall that is calculated will cover only the signals within that frequency range. If there were a large gear mesh frequency at 50,000 cpm, this measurement setup would miss it.

The calculation of “overall” using a spectrum is really an estimate of the overall filtered by the frequency range of the spectrum. The spectrum/calculation method for deriving “overalls” is often used to speed data collection, but there is a risk in taking such shortcuts for the sake of speed. One way to overcome the risk of missing a fault frequency is to measure multiple spectra with differing frequency ranges and resolutions. If this approach is implemented, the speed of data collection is significantly extended.

A preferred method is to measure the “overall” separately from the spectrum. This is similar to how a voltmeter would measure voltage and is the method recommended by the International Standards Organization (ISO) 10816-3 vibration standards. Using this “overall filter out” method, the raw signal is still filtered, but with a broadbanded band-pass filter that has both a high-pass side and a low-pass side.

Using the same 1800 rpm machine with a large 50,000 cpm gear mesh component, the high-pass filter set to 10 Hz (600 cpm), and the low-pass filter set to 1000 Hz (60,000 cpm), the measurement would be much greater than indicated by the calculated “overall” method. For root mean squared (RMS) measurement of overall velocity and displacement, the ISO specification 10816-3 recommends the frequency range in Table 1.

The ISO 10816-3 method is generally considered the safest method for taking “overall” measurements because it is less likely to result in an inadvertent exclude signal. Fortunately, the ISO also recognizes that 10816-3 does not cover all possible machinery fault frequencies. The ISO acknowledges that extending the filter frequency ranges and allowing additional measurements in units of acceleration may be necessary for some machines.

The important thing to remember is that the differences in measurement methods and filter settings can lead to large discrepancies between vibration instruments. These discrepancies alone do not necessarily mean that either instrument is inaccurate or out of calibration.

RMS vs 0-peak vs peak-to-peak
Another data collector setting that can make measurements look different is the amplitude method used in measuring the signal. For overall velocity measurements, the ISO recommends using an RMS measurement method to meet its standard. Traditionally in the United States, the 0-peak method has been used because some experts make a case that it is a better indication of the maximum vibration a machine experiences.

The ISO, and increasingly more experts in the United States, are turning to the RMS method as it is a better indication of the total energy being spent on vibration and thus relates better to the damage being caused by vibration. This can best be illustrated by thinking of a one-time sharp spike of vibration at 3.0 in./sec lasting only 1 millisecond. The 0-peak method would indicate 3.0 in./sec, which is high and would be cause for alarm.

However, the same signal measured using RMS indicates only 0.25 in./sec. RMS is 0.707 times the 0-peak value of a sine wave. Since the 3.0 in./sec spike is not a sine wave, the total energy of vibration is more accurately represented by the RMS value of 0.25 in./sec. Fig. 1 shows examples.

Peak-to-peak is generally used when measuring in units of displacement or mills. When monitoring journal bearings with proximity or eddy current probes that directly measure the gap across the journal bearing, clearance is the prime issue, not the energy of the vibration. If there should be 10 mils of gap in a journal bearing, yet a proximity probe is indicating 11 mils of displacement in peak-to-peak, there is a significant problem.

It is a common mistake to place an accelerometer on a journal bearing housing, integrate the signal to displacement, and compare the measurement to the proximity probe reading. These measurements are not the same.

Mounting accelerometers
Vibration measurements are sensitive to how the accelerometer is mounted and placed on the equipment. Measurements often change significantly when a vibration technician goes on vacation and another takes his place. A number of years ago it was common to see technicians taking measurements with a 9-in. probe screwed to the end of an accelerometer. There have been cases where a rolling element bearing failure was not detected because the mounted resonance of the 9-in. probe masked the bearing frequencies. By simply varying the pressure and angle of the accelerometer into the machine, the amplitudes of the measurement can be changed 30 percent or more.

Magnets are better than 9-in. probes, but they are not well suited for higher frequency events such as gear mesh frequencies and shock pulse measurement. Placement and cleanliness of the magnet also can have significant effects on the amplitude measurement. A magnet placed on a painted surface can have much the same effect as a 9-in. probe, masking bearing and gear frequencies.

Holding the magnet with one’s hand when taking measurements can have an effect on the amplitudes as well. When a vibration from the machine happens to coincide with the mounted resonance of a magnet, large amplitudes can be generated that have little to do with the actual severity of machine vibration. The combined differences between the size of the magnet and the mass of the magnet/ accelerometer/cable assembly also can have large effects on the resulting amplitude measurement.

Stud mounting accelerometers is a good technique for transferring a wide range of frequencies through the mounting seam into the accelerometer. As stated earlier, using different accelerometers and accelerometer mounting methods can lead to large discrepancies between instruments. To make stud mounting more convenient, there are several cam lock and quick mount methods available.

Response curves, configuration
Accelerometers have a linear response over a specified frequency range. Some accelerometers are optimized to measure low-frequency ranges and others are better at high-frequency ranges. Because the design of accelerometers is driven by specific applications, the linear response varies between accelerometer models and brands.

In a comparison between two models of accelerometers, Fig. 2 shows an accelerometer that is designed to measure low-frequency ranges down to 1 Hz and is not linear at high frequencies above 10 kHz. The response curve of Fig. 3 indicates that this accelerometer is not linear at 1 Hz but it is linear between 10 Hz and 20 KHz. While there is an overlap of frequency ranges where both accelerometers are linear, at the extremes of high or low frequencies they will present differing results.

Measurements taken with different accelerometers will not necessarily disagree, but if the vibration is not in the linear frequency range of one accelerometer and is in the linear frequency range of another accelerometer, the measurements will differ.

Accelerometers can give different signal outputs, which if not properly configured in the instrument, can cause vastly different vibration readings. It is imperative that the vibration instrument is properly configured for the accelerometer, or the results could be grossly in error.

Ensuring reliability
There are many reasons two different instruments may not produce the same amplitude vibration measurements. Both instruments can be correct yet display different values. The ISO has tried to standardize many of the variables that lead to discrepancies between measurements. Some of these are controllable, such as filter settings, but some are more difficult, such as magnet mounting.

Until more vibration suppliers adopt or include the ISO vibration standards, significant differences will continue to be a reality. What can be done to ensure the safe measurement of the vibration?

1. Examine the frequencies the equipment will emit by calculating such things as rpm, bearing frequencies, blade/vane pass frequencies, and gear mesh frequencies. If there are components that can emit high-frequency wear noise like rolling element bearings, be sure to consider high-frequency measurements like shock pulse.

2. Make sure overall measurements have the band-pass filters set to include several multiples of the bearing frequencies.

3. Take multiple parameters such as velocity, acceleration, and shock pulse. This will help avoid missing higher frequency events such as gear mesh.

4. Look at the accelerometer’s specification sheet and make sure it has a linear frequency range that includes the key fault frequencies calculated.

5. Use high-frequency measurements such as shock pulse to monitor the lubrication of rolling element bearings. Check with the data collector manufacturer for shock pulse compatibility, then verify which accelerometers and mounting methods are recommended.

6. Follow the ISO vibration tolerances whenever possible. This can be a great help when evaluating a new machine.

7. Use the measurement stud method of acquiring vibration measurements whenever possible. This will maximize the consistency of the measurements.

8. Be extremely consistent when taking measurements. Simple things such as wiping dirt and metal shavings off the mounting surface of the accelerometers can make huge differences in measurements.

9. Do not despair if what appears to be the same measurements from different instruments do not agree. It is typically something simple like a filter range or an RMS vs 0-peak issue. MT


Greg Lee is a sales engineer at Ludeca, Inc., 1425 N. W. 88th Ave., Miami, FL 33172; (305) 591-8935

TABLE 1. ISO 10816-3 FILTERS APPLIED TO BROADBAND RMS VALUES
OF VIBRATION VELOCITY AND DISPLACEMENT

 

Frequency Range From:

Frequency Range To:

Machine speed greater than 600 rpm

10 Hz

1000 Hz

Machine speed less than 600 rpm

2 Hz

1000 Hz

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MEASURING WITH AMPLITUDE METHOD

0604ludecafig1

Fig 1. Root mean squared is the preferred method of measuring the amplitude of the signal because
it gives a better indication of the damage caused by vibration.

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FREQUENCY RESPONSE/THREADED OR BONDED MOUNTING

0604ludecafig2

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FREQUENCY RESPONSE

0604ludecafig3

Figs. 2 and 3. Because different accelerometers are optimized to measure different linear frequency ranges,
they should be matched to a specific application.

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