How to
HANDLE COMPLEX LUBRICATION ISSUES COOPERATION BETWEEN LUBRICANT AND EQUIPMENT MANUFACTURERS SOLVES PNEUMATIC APPLICATION PROBLEMS By Helmut Seubert, Klüber Lubrication München SE & Co. KG Selecting the proper specialty lubricant There are less trivial types of leakage, for pneumatic components, drives, and though, which have to be remedied with control systems may involve complex facconsiderable outlay in terms of time and tors that require extensive tribological costs. Compressed air, for instance, is expertise to understand. That’s because expensive to generate, and therefore, fixpneumatic equipment incorporates a variing leaks is extremely important. There’s a rule-of-thumb saying that it ety of different elements—such as cylinders, motors, or valves—which are costs a nickel for each cubic meter of comprised of different materials that make compressed air generated. Each addithe tribological system highly complex. tional 14.5 psi of compressed air can be A decisive factor for ensuring maxiexpected to increase energy costs by mum service life and proper equipment approximately 10%. This means costs can function is selecting the right pre-start rise enormously, especially when leakages lubrication for all components that go undetected in connecting lines, check move relative to one another, e.g. pisand control valves, quick-fitting pipes, Complex pneumatic components that incorporate a ton rod, cylinder wall, valve slide, and maintenance units, or the terminal equipvariety of different elements, such as cylinders, motors, or valves, which are made of different materials, can be very sealing elements. Furthermore, the ment, such as pneumatic units. demanding in terms of lubrication. lubricants used for reducing friction Besides professional maintenance, and wear must also be tuned to the high-quality design elements—such as ambient temperature, sliding speed, and normal forces, just to name materials, sealing elements, and lubricants—are indispensable to a few factors. ensure economical operation and to extend or eliminate the need for As operating pressures, temperatures, sliding speeds, and stroke component replacement. Consequently, when looking at cost, what matters is not so much the frequencies continuously rise, design engineers and tribologists must carefully understand the friction factors where shafts or rods are taken cost of air compression as such, but rather how much energy is needed to make the compressed air available at the point of use. On average, through housing walls. At the microscopic level, the tribological system that encompasses approximately 33% of compressed air is generated only to vanish through the various gaps, spaces, and friction points involves such factors as a large number of small leaks that combine into a huge loss. intermolecular forces, A simple calculation reveals the expected losses—and the potential thermal transmission and conduction, for improvement. For example, a medium-sized company operates a friction and wear, and 100-kW compressor station with a total runtime of all compressors of chemical and electro-chemical corrosion. about 6,000 hours a year. At a rate of approximately $0.082 per kWh, the At the mechanical level, the tribological analysis must account for annual energy cost is about $48,700. If typical leakages can be prevented, cylinder and rod materials, however, the operator will need 30% less of compressed air, saving different seal materials and sealing edge geometries, roughly $15,000 on energy alone. contact surface pressure and surface micro-geometry, acting pressures, and How Collaboration Identifies Savings mounting position and situation. To prevent leakages from being caused by brittle seals, it is essential Additionally, environmental factors act on the components and the that the seal and the lubricant be compatible. In a recent case, both friction points, e.g. low and/or high temperatures or aggressive media hydrologic and lubrication manufacturers cooperated in using mechain liquid, gaseous, or abrasive form, such as sand, etc. These complex no-dynamical test rigs for tests that closely resembled application and factors are best handled when design and tribology engineers collaborate component realities. By combining knowledge, both parties identified early in the development process to identify the benefits obtainable opportunities for improvement. With the development of seal-and-lufrom proper lubrication selection. bricant combinations for the various tasks encountered in pneumatic systems, operators benefitted from improved pneumatic drives, valves, Preventing Leakage Means Less Energy Consumption and seals. As a result, the machinery was able to operate reliably for long Preventing leakage is key to developing successful pneumatic compo- periods while cutting energy costs considerably—a significant competnents. While a component is in operation, some leaks may go unnoticed, itive advantage resulting from early cooperation that identified the for example when water leaking from a pump evaporates on the spot. relevant tribological and operational factors. For more information: Helmut Seubert is manager, marketing and application engineering, for Klüber Lubrication München SE & Co. KG. He can be reached at helmut.seubert@klueber.com. www.IFPS.org • September/October 2016 • www.FluidPowerJournal.com
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