Magnetic Filtration Technology

The lubricants used to protect gearboxes, especially in high-demand industries such as wind, can become filled with ferrous particulates. The answer? Magnetic filtration.


Wind power is the world’s fastest-growing source of renewable energy that is capable over time of significantly reducing our dependence on fossil fuels. Growth is fuelled by technological advancements in design and production allowing large-scale energy production at a competitive cost per kWh. The design and quality of the turbine components will affect its ability to sustain reliable power generation with minimal costs over its operational life.

The operational integrity of the wind turbine is essential for profitability. To achieve maximum profitability a quality maintenance program is critical to ensure efficiency and longevity of operation. Premature wear of components is the main cause of component failure.

Lines of Defense
The first line of defense is the employment of a hydrocarbon management program to ensure quality coolant, lube oils, and hydraulic fluids designed for this application are employed. This type of program will also ensure the best practices procedures are followed in the storage and handling of these fluids and lube oils is conducted to ensure minimal foreign contamination opportunities. Figure 1

The second line of defense is the employment of quality filtration for these systems that will maintain a high level of cleanliness of the fluids and lube oils to ensure the maximum level of function and operational life. This is achieved by pre-filtering the new lube oils and fluids prior to employment into the gearbox, hydraulic, and coolant systems. The purpose of pre-filtering is to remove the ferrous metal contamination under 10 microns down to submicron levels that is inherent in new oils and fluids. This contamination is the result of corrosion and erosion of the carbon steel piping, storage reservoirs and pumping systems prior to packaging.

Industry has clearly identified ferrous metal under 10 microns down to submicron in size causes the majority of premature wear of the components in gearboxes, fuel, coolant, and hydraulic systems. Advancements in manufacturing capabilities have greatly improved the machining tolerances and clearances of the components (submicron range) employed in transmissions and gearboxes such as bearings, shafts, and seals. This also is true for hydraulic components such as valves, seals, and actuators. Filtration technology capable of removing contamination in the sub-micron range is now critical to maintain the operational integrity of these components.

It is important to understand the other sources of ferrous metal contamination under 10 microns in size for all these applications. It is first introduced as a result of the machine process, as it is very difficult to remove the fine metals on the surface of the metal parts used in the assemble of these systems. Casting of steel housings and parts also are a source of fine ferrous metal contamination. Welding of the components such as hydraulic reservoirs also produces fine metal contamination. Airborne ferrous metal contamination is clearly the most misunderstood source of ferrous metal contamination. It falls on the equipment components when being assembled and when the fluid or lube oil is being introduced into the equipment. Poor quality air breathers also introduce ferrous metal into the system. Once operational, the main source of ferrous metal in these systems is the contact between metal components such as gears, shafts, and pistons, etc.

Even with the best quality lubricants, the fine metal contamination in the lube oil or fluids will cause premature wear when they make contact. The fine metal contamination travels with the oil film between the moving parts and creates friction, vibration, and heat, all of which are detrimental to the life of these components, as well as the lube oil or fluid integrity. Ferrous metal will also wear the non ferrous soft metal and non metal components. Remove the ferrous or hard metals and the wear cycle will be reduced for the soft metals and non ferrous parts.

Protection from Particulates
Ferrous metal has been the most understated wear contaminant in most lubrication, hydraulic, and pneumatic systems, and the ability for traditional filtration to filter ferrous metal under 10 microns in size has been greatly overstated.

The most effective filtration technology to remove ferrous metals under 10 microns to submicron in size is with (rare earth) magnetic filtration. Traditional magnetic filtration has employed ceramic magnets that offer minimal ability as the strength of the magnetic fields is low and unable in most applications to remove ferrous contamination under 10 microns in size. Another problem with ceramic magnets is they are exposed to the fluid or lube oil to ensure maximum magnetic field strength, which creates a contamination issue as ceramics are brittle and will crack from temperature change and vibration, sending small particles into the system that attach to the ferrous metal components such as bearings and shafts. Most OEM equipment manufactures still employ ceramic magnetic filter rods and magnetic filter drain plugs. Figure 2

With the advancements in rare earth magnetic technology over the past 15 years, magnetic filtration technology has taken on a new life, offering filtration capabilities down to submicron levels of both ferrous and nonferrous contamination in transmissions, engine lube oil, fuel, coolant, and hydraulic systems. This is possible due the rare earth magnetic field strength is on average four times stronger than ceramic magnet fields. The extraction of nonferrous materials is due to the static charge build-up that occurs in these applications (static adhesion). The filtration of all new lube oils, fuels, coolant, and hydraulic fluids by quality magnetic filters prior to employment will remove the most damaging wear contaminant ferrous metal down to sub-micron levels and help reduce the premature wear cycle.

Ferrous Metal the Foe
The heart of the turbine is the gearbox, and its operational life is directly related to the quality and cleanliness of the lube oil that is protecting its components. The primary wear contaminant is ferrous metal, and in most applications a magnet filter is all the filtration that is required to maintain a high level of cleanliness that will extend the lube oil life and dramatically reduce the wear cycle thereby extending the component life.

The hydraulic system on the wind turbine is also crucial to the operation and the fluid has to be contaminant free down to the submicron level. This can be achieved by the combination of a quality magnetic filtration and a depth media filter. Ferrous metal contamination in a coolant system will affect its ability and operational life, it also prematurely wears the system components.

One Eye Industries (OEI) is an industrial filtration manufacturer and has designed and patented magnetic filtration technology that is employed in many formats as a standalone filter for many applications and compliment traditional depth media filters. OEI has also developed the ADD-Vantage 9000 filter series that combines a cleanable stainless cloth filter element (200 Beta) and our magnetic filter together, creating an environmentally friendly and highly efficient filter. When employed in full flow and bypass filter applications will reduce downtime, maintenance costs, and improve your environmental footprint, as they are easily cleaned and have an operational life of 10+ years. A major key to reducing costs and environmental impact in wind energy is employing highly effective reusable filtration, but disposable filters are costly and unable to filter to the submicron level required by modern mechanical equipment. They also have a significant negative impact on the environment.

OEI’s filtration solutions have been employed in the mining industry for the past 10 years on gearbox and hydraulic applications, with customers realizing up to a 25-percent reduction in maintenance costs and up to three times component life extension. They are also extending PM periods by two and three times the norm, which has many positive cost savings for end users. A cost factor not taken into account enough is contact cycles between the technician and the equipment for maintenance or repair; reduce the contact cycles, and you will decrease the opportunity for injury.

Our environment has been damaged greatly by the industrial revolution, and disposable filters are part of the damage. What is the logic behind a onetime use of a product like the disposable filter? The energy costs and emissions created during the manufacturing of a disposable filter and the disposal costs once used make the disposable filter the most inefficient product in industry. Over 80 percent end up in a landfill with four to six ounces of oil absorbed into the media. The oil industry is sourcing new deposits, harvesting and refining the oil only to have industry put it back in the ground in our landfill sites. It also begs the questions of how much energy is used in the oil industry, and what is the volume of emissions created for a onetime use of the oil?

Wind energy is a wonderful environmentally friendly energy source. When there is a technology that compliments and increases the positive environmental impact wind energy has and increases productivity and reduces costs, it is important to take notice. The work we’re doing at OEI is part of the solution.