Motion Control recently paid a visit to filtration specialist, Filter Focus, to find out how effective oil filtration can dramatically extend the lifetime of a machine.
The silent thief
According to COO, Craig FitzGerald, contaminants can take the form of dirt, sand, paint, moisture, metallic wear particles or fibres. Oil leaving the refinery will be in specification, but contaminants can enter an hydraulic system at any stage – when the machine is built, or during storage or transport of oil, introduction of new oil, maintenance and service, or machine operation around worn wiper seals or dirty connectors. “Even before a breakdown, efficiency in an hydraulic system can drop by 20% before the operator detects a change, losing a day of productivity each week. Contamination in oils robs you of profits without your knowledge – it’s the silent thief,” he says.
A snowball effect
Contaminants have sharp edges and they cause abrasion as they scrape down smooth surfaces. Every contaminant particle can create three or four more wear particles and every one causes scarring and wearing – a snowball effect. Electrohydraulic valves with very small clearances of 3 to 4 μ are even more susceptible.
Contamination already in the system moves to the hydraulic cylinders where additional dirt can enter the system through nicks in the cylinder rod. These particles scratch the cylinder wall and accelerate wear on the piston walls before moving on to the filter. Even high efficiency filters do not remove all particles in a single passage and many return to the system through the centre tube. Effects of contamination on a hydraulic system are cylinder drift, shorter service intervals, jerky steering, erratic operation, slower performance, lost productivity, higher operating costs and even catastrophic failure.
More sophisticated systems have tighter tolerances
FitzGerald explains that in past years hydraulic pressures were lower than today and clearances between internal metal surfaces were not as tight; but today customers want more power, higher breakout forces and faster cycle times, while at the same time reducing the size of their hydraulics. Industry is responding with more sophisticated fluid system designs. Higher pressures, tighter clearances and electrohydraulics have made today’s products more productive and easier to operate, but they have increased the need for clean fluid systems.
The solution
“The solution is to ensure clean fluid through proper filtration,” FitzGerald continues. “People are not aware of the extent of contamination in their systems and what it is doing to their equipment, but these problems are easily addressable. We regard our filters as the best globally and they have been tested and proven in many applications.”
Filter Focus likes to install its systems on the equipment while it’s in operation, even with the dirtiest oil. It’s 10 times cheaper to eliminate a contaminant than to use filters, so the company use breathers as the first line of protection to prevent ingress of contamination, while the filters deal with contamination already in the system. To reduce the cost of filtration, 0,2 μ filters are installed all the way down the process, together with desiccant silica gel cartridges that absorb any moisture in the atmosphere before it gets into the oil.
He describes how operators of hydraulic systems will typically drain their oil and test their systems once a year. Filter Focus can use oil analysis to determine the health and internal workings of a machine, as well as the condition of the lubricating oil and often finds that one hour after service the oil is not fit for use. However, with proper filtration this can be extended to 1000 hours. “If we connect our filter systems after one hour of running, we can show that within 15 minutes the oil is back in specification and will remain there for an extended period of time,” he adds. “You may have the best filter in the world but one pass only takes out 40% of the contaminants at best – you need multi-pass filtration. Best practice is to filter the oil before it goes into the hydraulics but often this does not happen.”
Massive savings for Kumba
When Filter Focus installed its filtration systems at Kumba Iron Ore, the life expectancy of the lubricating pumps was extended tenfold and the lifetime of the socket liners on the primary crushers was extended from four months to 3,5 years. Previously the plant was stopped four times a year, with 12 days of shutdown. Now it shuts down once a year for basic maintenance. On a crusher that processes 6000 ton/hr this results in savings of R2 billion a year. It also made a significant impact on safety levels, because filters don’t have to be serviced as frequently and the risk assessment level has reduced from 42 to 0,5.
“The problem is that customers plan for failure rather than conducting a root cause analysis which could eliminate the problem,” concludes FitzGerald.
For more information contact Craig FitzGerald, Filter Focus, +27 (0)11 466 1268, [email protected], www.filterfocus.co.za
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version