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Equipment Reliability
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A reader asks, "Does F really equal MA?" I tried to answer his question. I expect some readers would answer it differently. Want to try? We'll publish one or two in the next issue. Are you having difficulty convincing your management that training should be considered an investment (rather than an expense)? Perhaps "Send Joe to a course?" will give you some ideas. Will you be traveling through Santa
Barbara?
Best wishes, |
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The Saber
Saw as a Tool for Automobile Maintenance
I once had problems with a car radio and tried to remove it from the dashboard for repair. However, there seemed to be no logical way to reach it, so I referred to a shop manual. It said that to remove the radio, first remove the glove compartment. I was surprised to find that a job, which should have been simple, was made quite complicated thanks to an absolute disregard for maintenance by the designers of the dashboard. This was my rude awakening to the fact that automobile companies seem unconcerned about the occasional maintenance needs of their cars and trucks. This disregard is so bad it has become legendary. Perhaps the worst example is the case where spark plugs in one model could be replaced only if the engine was unbolted from its mounts and raised away from the frame. In another case, the shop manual for a car said that to repair the heater, an access hole had to be cut in the fender liner. Compounding the problem are aftermarket service manuals that often are carelessly incomplete. Once when I was immersed in the job of adjusting mechanical valve lifters and faithfully following a manual, I realized that a standard wrench couldn't reach one of the adjustment nuts. It turned out that a special tool was needed, but no mention of this was made in the manual. On another occasion, I gave up trying to install a timing belt because I couldn't reach the pulleys, then found out later that the manual omitted some necessary disassembly steps. The defining moment in ending my career as a mechanic came when I tried to replace a burned-out headlight on my mother's car. Headlight replacement is normally routine, and I had done it many times. But on this occasion I was stumped. When I broke down and finally took the car to a mechanic, he explained that a large piece of the grill had to be removed to get at the headlight. After that, I vowed to stop doing maintenance on cars. That brings me to the seat-belt retractor in my wife's 1986 Buick. Recently it locked in the retracted position. Going back on my vow, I tried to fix the problem, but a large molding covered the mechanism as well as the front and rear doorsills. To make matters worse, some of the screws that had to be taken out to remove the molding were almost impossible to reach because the front seat didn't allow enough clearance for a screwdriver. So I took the Buick to a shop, where the mechanic had nothing but bad news. He said that although this type of failure is common, retractors normally can't be repaired, and replacements are no longer available for 1986 models. He would have to call junkyards to find one, and that would take a while if, indeed, he could locate one at all. It became obvious that the only solution had to be a drastic one. Re-sorting to my electric saber saw, I cut through the molding to get to the retractor. Then I found it was in a plastic housing with no apparent means of disassembly. So I continued cutting away until I reached the mechanism. That let me unlock a jammed pawl and unwind the belt so it could be used again. This left the car with a large gash in the interior trim, but you have to do what you have to do. All of this points up how car designs are dictated at every turn by minimum-cost construction that makes repairs difficult. Automobile companies pursue this cost reduction relentlessly year in and year out, and in the process, the problem keeps getting worse. Ronald Khol, editor of Machine Design magazine, kindly gave us permission to use his article. It appeared in Machine Design, September 13, 2001. |
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Evaluate the
Value of Training "In a company valued by its owners for its ability to generate cash, training is often seen as an expensive waste of capital," wrote one respondent to Quality Online's training survey. According to a recent American Management Association survey, there is a direct correlation between increased training activities and improvements in worker productivity, profitability and shareholder value in both the short and long term. The report states, "Companies that increased their training activities were three times more likely to report increased profits and shareholder value than companies that cut back on training. They were 66% more likely to report productivity improvements, twice as likely to reduce their turnover rates and 150% more likely to improve the quality of their products and services." While 93.3% of the respondents to Quality's Online survey said their employer provides on-site, off-site or both types of training for their employees, 6.7% said their employers provide no training whatsoever. One of the respondents at a company that provides no training said, "You figure it out the best way you can." Fortunately for most respondents, that kind of experience is most likely minimized due to the on-site or off-site training that their employers provide; 86.7% of the respondents said their companies provide on-site quality training for their employees, and 82.2% said their companies pay for employees to enroll in quality training courses offered outside of the workplace.
Of those responding, 46.7% said the majority of the training budget is spent on teaching quality management principles. The remainder of the training budget is divided among training on how to use equipment, 15.6%; part inspection and measurement, 11.1%; and quality software, 2.2%. Despite its importance to the bottom line, training accounts generally for a small percentage of costs. In the Quality Online survey, 74.4% of respondents said that 0% to 5% of the total budget is spent on training at their companies. Another 15.4% put training expenditures at 6% to 10%, while 7.7% said 10% to 20% of the budget is spent on training. Only 2.6% of the respondents work for companies that spend more than 20% of the budget on training annually. The survey respondents work for companies of varying sizes. And while some might expect that the smallest companies would be least likely to provide training, the survey results don't support that. In fact, all respondents who work for companies with fewer than 100 employees said their employer provides training of some kind. The 6.7% who said their companies provide no training at all work for firms of all sizes, ranging from 100-to-500 employee firms to those with 1,000 employees or more. Quality Magazine has kindly granted us permission to publish the above article from the April 2002 issue. |
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Send Joe
to a Course? Which requires the greater investment by Joe's employer? Which most benefits his employer? Which most benefits Joe? These are the questions which I will try to answer. I'm going to assume that the questions apply to vibration and shock training. Why? Because that is the area of engineering that I happen to know. I think that the questions and the answers are just as applicable to short courses dealing with climatics, with EMC/RFI, with ESD, with CAD, with FEA, etc. Does it matter whether Joe is a "design guy" or a "test guy"? Not much, in my opinion. It is unlikely that either Joe had much practical training in vibration and shock, climatics, EMC/RFI, ESD, CAD, FEA, etc. in engineering school. Both test engineers and design engineers need to "speak the language" of the specialized engineering area in which they finds themselves working. Which requires the greater investment? Which most benefits our organization? On the other hand, there exists another benefit to sending Joe to a short course: in talking with his fellow participants at an "open" course, Joe may pick up some ideas that are very useful to Joe's employer. Joe may also use those contacts in future. He might borrow a piece of test equipment or collaborate to solve a mutual problem. Which most benefits Joe? Travel Conclusion Wayne Tustin, ERI's president, can be reached at tustin@equipment-reliability.com or at 805/564-1260. |
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Questions our readers have asked... This section of our newsletter was created for you, reader! Feel free to send questions or suggestions to the webmaster. They will be responded to by one of our specialists. Q: Does F really equal MA? But don't go too high in frequency. Don't get into the region where that inertial mass or the internal spring or the case begins to resonate. Another consideration: most of your test articles are vastly more complex than the one-spring, one-mass system inside your accelerometer. Imagine that you are preparing to perform a 1g sine sweep on some DUT (device under test). On your fixture, in the usual way, alongside the DUT, mount one or more accelerometers to read A. Between your fixture and the DUT, install one or more force sensors to read F. Command your controller to hold A constant at 1g. Plot both A and F vs frequency. You will find that F varies markedly. At some frequencies your shaker must develop much force F; at other frequencies, little force F. That should convince you that your test article is not a pure mass. It can be modeled as a collection of springs, masses and dampers. Don't think of it as a single mass M. Don't count on F= MA. |
Welcome
to the third issue of 2002. We've kindly been permitted to use two
editorials from other magazines. One, entitled 
Coming
as a tourist? Give Wayne a call at his home office: 805/564-1260.
He might be available at some time during your visit. To learn about
"tourist" Santa Barbara, visit the following websites:
The
most popular type of training provided is hands-on, which is made
available to 68.9% of the respondents. Hands-on training is followed
by classroom, 64.4%; seminars, 60%; book/workbook, 5 1.1%; computer,
35.6%; and video, 31.1%. |
Last chance
to enroll!
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Fundamentals of Vibration and Shock Testing - Aug 12-14 Optimizing Electronic Circuit Card - HALT, ESS and HASS - Aug 19-21 Contaminants and Moisture can Disrupt your Electronics - Aug 26-28 |
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New features
at ERI website
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Check on the new message board section or find previous issues of ERI's News. If you would like to advertise at ERI's website, visit our ads page to get details. We welcome feedback! |
Wayne Tustin will teach the following short courses in vibration and shock measurement, analysis, calibration, testing, HALT, ESS and HASS: Santa Barbara, California, Montreal, Quebec, Canada, Billerica (Boston), Massachusetts, St. Petersburg, Florida, October 28-30, 2002
Pico Rivera (Los Angeles), 2003 courses: Santa Barbara, California, February 11-13, 2003 Washington
DC, Huntsville,
Alabama, |
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Announcements
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Vibration and Shock book Seeking teacher |
| Check our Glossary |
Check our Vibration and Shock Glossary. We have just added new words and their definitions. This list evolved from Wayne's 50 years of teaching; it is constantly updated. |
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Contact
information
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Wayne Tustin tustin@equipment- Webmaster webmaster@equipment Web sites Copyright © 2000-2002 Equipment Reliability Institute. All rights reserved. |
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