More and more manufacturers are trying to use less or even no lubrication. Is it time for a lubricant-free industrial world?
Malfunctions due to deficient lubrication cause $240 billion in damage in the U.S. every year, and the resource waste resulting from excess friction exceeds 6% of GDP. High-performance lubricants are now being produced. But best practices also include reducing lubrication or even eliminating the need for it altogether.
Atlas Copco has pioneered the development of oil-free air technology. In 2006, its Z compressors were the first to be awarded ISO 8573-1 Class 0 certification after no traces of oil were found in the air stream. They are designed for industries requiring the highest levels of air purity, including the food and beverage, pharmaceutical and medical sectors.
Mark Ranger is manager of the oil-free air division:
In these critical environments, contamination by the smallest quantities of oil can result in costly production downtime and product spoilage. So every compressor installation would benefit from being lubricant free.
Atlas Copco recently expanded its offer. The new ZH+ and ZH 630-1600 kW compressors offer high-end turbo technology in an efficient package with a small footprint.
They are based on an all-inclusive, plug-and-play concept, with intelligent control and remote monitoring capabilities. They offer users a total energy efficiency gain of approximately 6%.
A Critical Environment
German dairy company DMK processes 1 million liters of milk into cheese every day, and uses Atlas Copco’s oil-free, water-cooled ZR compressors to supply the needed air. In the past, the company used oil-injected compressors. They filtered the oil from the compressed air using activated carbon and other filters. Ultimately, this method was not reliable enough and became costly, as the filters require frequent changing.
For Johannes Bechtle, technical manager at DMK, a lubricant-free system has definite advantages.
Since the installation of the new machines, energy consumption has been reduced from 12,000 kW hours to 10,000 kW hours per week, and the improved regulation has meant no-load hours have decreased by 1,000 kW hours per week.
For Ranger, oil-free compressors mean lower investment costs over a typical 15-year period.
They eliminate lubricant oil costs and reduce operational energy costs because without filters, we no longer see such high system pressure drops. The challenge is to balance higher initial investment with reduced through-life costs resulting from lower maintenance and reduced energy expenditures.
Smardt Chiller Group provides equipment using oil-free technology in a range of high-efficiency chillers. For example, the Danfoss Turbocor compressor employs lubricant-free magnetic bearings. CEO Roger Richmond-Smith explains:
The magnetic bearings allow the compressor to operate without the use of lubricant, reducing energy losses due to friction and increasing the heat transfer efficiency of the chiller, as no oil enters the evaporator or the condenser. The oil-free system also eliminates the need for oil maintenance.
Plastic Bearings and Self-Lubrication
The German company Igus manufactures injection-molded dry-tech bearings from its own iglidur polymer. In addition to the polymer base and reinforcing fibers, they contain millions of tiny solid lubricants that provide self-lubrication, making external lubrication unnecessary.
Rob Dumayne, Igus director of dry-tech, explains that this alternative to lubricated plain and roller bearings allows continuous dry running.
Our bearings are environmentally friendly, as no lubricants are discharged into the environment, and also energy saving, as they are up to seven times lighter than a metal bearing. Replacing metal bearings with our plastic ones saves around 40% in parts maintenance.
Lubricant-free: The trend of the future?
For Dumayne, the answer is yes.
I can see a future that is lubricant-free, where companies use whole systems that are dry running, as efficient as those with lubricants, more environmentally friendly and absolutely maintenance-free. People are trusting plastics more.
But why aren’t lubricant-free systems more common today?
Initial capital cost is seen as the barrier and the hidden benefits of reduced through-life maintenance and lower pressure drops resulting in lower energy consumption are not always considered at the outset of new investment projects. A typical compressed air system, if engineered correctly from the start, should realize a 15- to 20-year lifespan. Longer periods between service interventions and [eliminating] the costly replacement of filter elements would all contribute to genuine through-life operational cost reductions if an oil-free compressor were installed.
I think many people are either not aware of the potential of dry running plastic systems or they don’t necessarily trust them. However, once the benefits of these are demonstrated, most become less skeptical. I think it is about educating the masses.