The benefits of Precision Maintenance you get include massive maintenance cost reduction, outstanding equipment reliability, and deferment of capital expenditure.
Precision Maintenance is the purposeful prevention and removal of stress from the working parts of machines and equipment. It requires the use of fine workmanship techniques to deliver high accuracy in the positioning and movement of the parts.
The benefits of precision maintenance include reduction in costs between good and bad machines of five to ten times less. The practice of Precision Maintenance offers you these potential savings by bringing all your machines to a good-health state and smooth running condition.
The following is a reproduction (and metrication) of a paper explaining the proven benefits of precision maintenance presented by it discoverer, Ralph Buscarello, as his keynote address to the Vibrations Association of New Zealand in May 1998.
Most of the people in this audience are probably already convinced that machinery vibration results in shorter bearing and seal life as well as other forms of premature machinery failure. A great number, in a group like this, already have the technical knowledge and equipment to not only perform good predictive maintenance (picking out the bad machines from the good), but also use that same knowledge to cause the machines they affect be run considerably smoother than ever expected when new. They also know that smoother running machines enable considerably longer production running times, less scheduling headaches, and so on. Obviously, the supervisors and managers of their companies would also like to experience lower maintenance costs while increasing production-running time. So, why would there be hesitation or outright resistance to these practical steps that bring about true machinery improvement?
Sometimes it’s our own fault, that is, the fault of we vibration specialists. For managers to approve any investments in time, money, or even new procedures, they have to first fully understand what they committing to so that they know they aren’t opening a “can of worms.” In addition, they need to see real and verifiable financial returns that make their investment truly worthwhile. At those all-important meetings and conferences, reports are presented that use technical jargon, relatively unfamiliar words, and expressions such as “amplitude, phase, phase shift, harmonics, sidebands, non-synchronous, synchronous time averaging, etc.” For the manager that has to determine whether to shut down the machine or not, this could be very disconcerting and frustrating. What supervisors and managers need are facts—in their own language—and their language necessarily is the language of the accounting department, not the engineering or maintenance department.
Let’s look at some of the financial facts as provided by companies with considerable savings as a result of vibration analysis, correction, and reduction for true machinery improvement.
Figure 1 is the comparison of previous year’s maintenance cost vs. vibration amplitude for 1800-rpm pumps, in one department of a paper mill.
Figure 2 is the comparison of previous year’s maintenance cost vs. vibration amplitude for 3600-rpm pumps, in one department of a paper mill.
When I first viewed these graphs, I simply observed, as we all do, that the downward trend for maintenance costs generally followed the decrease in amplitudes. However, we all knew that would happen. Later, I focused on a predetermined vibration level, such as 1.0 mm/sec, and worked my way to the left, until it generally crossed the maintenance costs for pumps. Notice that for the 1800-rpm pumps with running smoothness of approximately 1.0 mm/sec and lower, the previous year’s maintenance costs were approximately under US$8,000. For only 2.5 mm/sec which many analysts consider good, the costs more than doubled to about US$15,000. For 3.8 mm/sec the maintenance costs were about US$22,000 per pump (and we haven’t even started to look at the pumps with what are usually considered as bad vibration levels).
For Figure 2 (3600 rpm pumps), the figures were different but showed the same pattern. At 1.0 mm/sec, the previous year’s maintenance costs were about US$9,000. For approximately 2.5 mm/sec the costs were about $US18,000. (There are serious financial benefits of precision maintenance)
Before supervisors, managers, and even yourselves truly act on what should be done for machinery improvement, it is important to find out your own company’s maintenance costs. Do this for simple machines that are readily available, such as ordinary motor/pump assemblies, fans, blowers, chilling equipment, and centrifuges. Include all related charges, not only for parts, labour, and a few benefits, but also include supervision and all other overhead charges.
One large oil refinery did this by calling any motor/pump one repair whether it included only one item, such as changing one bearing, to several repairs on that same pump (during that same shutdown). They did not differentiate between small or large pumps, vertical or horizontal, low speed or medium speed. They entered all the pump/motor maintenance costs into the maintenance department computer for one year. They divided the total by the number of motor/pump repairs.
Figure 3 is the comparison of pump maintenance cost vs. vibration amplitude.
About 10 years ago, the result was slightly over US$10,000 per motor/pump. It sounds like an exaggeration until you look at the previous graphs one more time. Only the pumps with less than 1.0 or 1.25 mm/sec came even close to that figure. Even motor/pumps with what most analysts call a good or okay vibration level of 2.5 mm/sec produce costs that are double that.
Real (benefits of precision maintenance)? Exaggerated (benefits of precision maintenance)? Just a bunch of figures used by typical seminar speakers to make a sale? I don’t blame you. The figures looked incredible to me as well. Therefore, I’ll give you a very worthwhile homework assignment. That is, do not accept any of the dollar figures given by other plants. After all, their machinery might be much different or even running at a higher horsepower. Get your own numbers from your own machinery. Then, you will have the data that enables you to choose based on knowledge gathered by your people rather than a wild guess.
Let’s assume that these figures are verified. Then take a look at predictive maintenance and condition monitoring using the same technical knowledge to not only properly analyse and correct that machinery, but to also conduct a program of machinery improvement.
The procedures are all within your knowledge. They include:
- precision balancing to modern standards instead of obsolete ISO standards that were developed in the early 1960’s
- precision alignment to much closer tolerances than given by flexible coupling manufacturers
- much more careful base preparation and shimming
- eliminating foot-related resonance as well as soft feet
- precision assembly procedures that preserve precision balance
- complete vibration analysis (with the analyst and mechanic/technician who assembled the machine together) at start-up
There’s more, but all are with the abilities of mechanics/technicians that are taught the five points of precision work that takes only a little more care than for ordinary work. Is it worth it? Again, let’s look at the financial figures from another perspective before we concentrated on maintenance costs. Now let’s see how even those cost savings are small compared to the financial figures for increasing plant production capacity. You probably have considerable local case histories on this, but too often we focus on the maintenance costs and sometimes neglect to see what we’ve accomplished by having each improved, smoother running machine run anywhere from 50 to several hundred percent longer.
The numbers will be very large compared to the numbers for much smaller plants, but we’ll look at the results at smaller plants, later. At the very large aluminum plant, they at first focused only on large pumps over 100 hp. They originally ran their pumps to failure, but by using precision methods as described above, they cut their pump repair costs in half. But, that’s not the point! In six years, they increased their machinery running time enough to increase production by slightly over 100 percent.
At this juncture, it’s tempting to simply count the dollar value of that increased production (gained from the benefits of precision maintenance). Instead, a company production vice president had a study conducted to determine how much it would cost to obtain the same increased production through new plant expansion (machinery, land, buildings, engineering, etc.). The total was over US$1,000,000,000—wow!!
That statistic could easily turn you off as most work is done in much smaller plants. However, you can still use the same principle regarding plant expansion costs for even the smallest production unit. At this point, one seminar participant objected that I used case histories about large plants with lots of machinery, including high horsepower machinery. His plant manufactured a well-known brand of candy bars and most of his motors were around 5 hp and only rarely above 10 hp. He, therefore, objected to these principles and felt they didn’t apply. No reasoning that I gave changed his thinking. Neither did the plant tour he gave me (to show how small his motors were).
The tour took about an hour. They had around 15 major conveyor lines whereby candy ingredients would automatically build up into the complete bar as the conveyor moved under each piece of food machinery. Each conveyor line was about 100 feet long. In that one tour, there were three lines that were completely stopped while their mechanics made their repairs. While changing their (yes, 5 hp) motors, their very expensive automated electronic control equipment/mechanical equipment—all along the line, were shut down—for what could have seemed like a minor mechanical repair.
Then there is the maintenance manager from a hospital who attended one of our seminars for supervisors and managers. I couldn’t imagine that a hospital had nearly as many machines as a small process plant, or would almost all the machines be very large. He agreed, but added, “In addition to air conditioners and pumps, how would you like the small motor on a heart/lung machine to fail during your by-pass surgery.” And, then something I would never have thought of, he stated, “Do you know how many lawsuits we get when the oxygen supply fails to deliver to people with tubes in their nose?”
One more case history—here goes! I arrived in Southeast Asia to conduct a seminar for an oil company. At their location, they had only about 50 rotating machines. When I commented that such a small plant didn’t usually pay for a whole seminar, the retort was, “We pump many thousands of barrels per day with only 10 major pumps. Do you realise the percentage we don’t pump when only one machine is down?”
In over 46 years in teaching vibration reduction and conducting seminars in over 34 countries, I could produce hundreds of outstanding financial case histories (of the benefits of precision maintenance), many involving millions of dollars. However, for those who remain sceptical, I suggest you accept none of my figures. Instead, start with the first idea of measuring the vibration levels (taken at the worst point) on about 50 ordinary but common machines, such as motor/pump assemblies. Plot the trends of their previous year’s maintenance costs on the same graph as their vibration amplitudes. Then make up your mind as to whether reducing vibration to precision levels pays off or not!!
Best regards to you,
The Benefits of Precision Maintenance is printed with permission from Industrial Training Associates