Hydraulic systems are indispensable in many areas of industry. Their performance and service life depend largely on the purity of the hydraulic oil and the cleanliness of the components. Whilst most users know that hydraulic oil is the central pressure medium in a hydraulic system, its maintenance is often neglected - and this can have fatal consequences. Contamination in the oil or on the components leads to premature wear and expensive breakdowns. Here are the most important factors that you should consider.
picture: stauff
The importance of oil cleanliness
Up to 80% of hydraulic system failures can be attributed to increased contamination of the hydraulic oil. This is because modern hydraulic systems are extremely sensitive to contamination. The cleanest component determines the required cleanliness of the entire system. Hydraulic systems often work with an oil film that is less than one micrometre thick. By comparison, a human hair is about 70 micrometres thick. Impurities in the oil that are smaller than 30 micrometres cannot be seen with the naked eye. Nevertheless, these tiny particles can cause great damage.
Contamination enters the hydraulic system in various ways, for example through uncleaned lines during assembly, abrasion during operation or improper maintenance and repairs. Even new hydraulic oil often does not fulfil the required cleanliness class and should be filtered before use.
Image: Oil filtration units from Stauff
Filter fineness and filter types
Various filters are used to ensure that the hydraulic oil has the necessary purity. A common standard for determining filter performance is the beta value ß, which is measured in the multipass test in accordance with ISO 16889. This test shows how effectively a filter retains particles of a certain size. For example, ß10 (C) = 200 means that 99.5% of particles larger than 10 micrometres are captured by the filter.
Choosing the right filter is crucial to protect the hydraulic system from damage. The most important filter types include
Filler and breather filters: They prevent particles from entering the hydraulic tank with the air.
Suction filters: They protect the pump from coarse impurities.
Return line filters: These offer cost-effective full-flow filtration and are compact.
Pressure filters: These guarantee the protection of downstream hydraulic components.
Off-line filters: They filter a partial quantity of the volume flow and are particularly effective in heavily used systems.
Technical cleanliness of components
In addition to oil cleanliness, the cleanliness of the hydraulic components also plays a decisive role. Foreign particles in components can contaminate the oil and significantly shorten the service life of the system. Manufacturers such as Stauff have recognised that technical cleanliness is not only important for the automotive industry, but also for hydraulic systems in other areas. Stauff is committed to a maximum particle size of 500 micrometres without incurring additional costs for customers.
Strict measures in production ensure the cleanliness of the components. For example, all parts are transported in closed containers to prevent the ingress of dirt. In production, chips and oil residues are removed by washing systems and assembly steps are carried out under clean room conditions. These measures lead to significantly lower particle counts and smaller particle sizes on the components produced, which considerably improves the longevity of the systems.
Conclusion: cleanliness is the key
Whether it's the purity of the hydraulic oil or the technical cleanliness of the components - both are essential for the reliable operation of a hydraulic system. Early and consistent maintenance and the use of suitable filters can prevent expensive failures. Manufacturers such as Stauff show that maximum cleanliness does not necessarily have to be associated with high costs. By paying attention to these factors, you can ensure that your hydraulic systems operate efficiently and trouble-free over a long period of time
Click here for the Stauff oil filtration devices in our online shop.
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