Efficient Lubrication of Hydraulics
Lubrication of hydraulics is a major, key area in a wide range of industries. Efficient lubrication can save energy, assure technical performance and extend the useful life of both the lubricant and the hydraulic systems.
Reduce energy consumption and withstand the cold
One rule of thumb is to choose an oil with the right properties, especially in terms of viscosity. Oils with lower viscosity are easier to ‘pull’ around the hydraulic system, thus reducing energy loss and saving money. Many people choose a high-viscosity oil out of habit, but this is an area worth reflecting on to achieve improved lubrication and lower costs.
Also, a lot of technical systems are kept outside at all times of the year. For these systems, choose a hydraulic oil that can withstand low temperatures and eliminate the need for heaters in the hydraulic reservoir, which use a lot of energy. With the right product, the systems will start even when the cold sets in. These lubricants also reduce energy consumption.
Talking of low temperatures, hydraulic oils with too high a viscosity can cause problems in cold starts. A thick oil could damage the hydraulic pump, leading to breakdowns in the worst cases. The solution here too is to use lower-viscosity products. These ensure a reliable start during the cold season, they lubricate better and maintain their performance over time.
Cleanliness is key
Dirt increases the risk of operational disruptions. In hydraulic systems with a high turnover rate, just a small amount of dirt being pushed through the system is enough to cause disruption or damage. Therefore, make sure the system is clean by using the right type of filter. It’s just as important to take great care and keep everything clean when refilling or doing anything else to the system.
Another tip is to use ester-based oils. Several of these products have a cleansing effect while also preventing the formation of varnish. Furthermore, many ester-based oils have better lubricity than traditional mineral oils.
Avoid devastating contaminants
If a hydraulic oil becomes contaminated, it can have devastating effects. It is therefore vital to keep water, for example, away from the oil. This means keeping the water content below 200 ppm in a mineral oil, so ensure that the system has a respiratory filter with a desiccant cartridge fitted. This prevents condensation from forming, but also filters out particles that can contaminate the oil.
In engine oils, just a few drops are enough to completely nullify the properties of the hydraulic fluid. The fluid loses its ability to separate water, which instead binds with the oil and worsens its performance. One good tip is always to use separate refill containers for different lubricants, since this reduces the risk of contamination.
Degreasers can also ruin a hydraulic oil. Therefore, be sure to rinse carefully any machine parts that have been degreased. Also, never pressure wash sensitive parts in a degreased system, as this can push water and degreaser into gaps and openings and contaminate the oil.
Secure performance and life span
A longer life span means fewer oil changes, saving both time and money. A mineral oil that’s correctly maintained – and works at a maximum temperature of 40 degrees Celsius – has a useful life of around 20 years. But that useful life is halved for every ten degrees the temperature increases. So there is much to be gained by keeping the temperature down. It’s a good idea to regulate the cooling with a thermostat, but also to ensure the air or water cooling system is clean and working properly.
Pressure drops in a hydraulic system produce a heating effect that can also shorten the life of the oil. A pressure drop can happen if the overflow valve is left open and the pump doesn’t work properly. This can most simply be avoided by fitting the valve with pressure control – that way it won’t remain open and drive up the temperature.
Another tip is to use biodegradable products; many of them have a longer life than regular mineral oils and often provide better technical performance.
Last but not least, take care to avoid the diesel effect. The diesel effect occurs in systems with too low a pressure as gas bubbles form in the oil. These bubbles then ignite and cause a micro-combustion, forming nitrogen oxides. Over time this darkens the oil, it starts to smell acrid and performs worse.
Low pressure can arise if:
- the oil is too thick
- the hydraulic pump’s suction pipe is under-dimensioned
- the pump is too high up in relation to the hydraulic reservoir
FUCHS offers solutions aimed at increasing energy and efficiency through the targeted selection of hydraulic oils and the consideration of new requirements for shear stability, thermal and oxidative stability.