You will read a lot of advertisements and technical articles about the particulate efficiency of many types of hydraulic filters being marketed today. Very few address the “hidden” killer of hydraulic system efficiency and accuracy – oxidized oil.
HTI recently received a call from a major furniture manufacturer who told us that their hydraulic fabricating machine has recently turned into a scrap metal making machine. They had resorted to hand cleaning each servo valve every weekend to try to maintain the accuracy of their punching programs! A quick analysis of the valves and oil revealed the presence of varnish in the spool landings and in their oil.
Oxidized oil, commonly known as varnish, typically occurs when oil is heated and the resulting goo adheres to whatever surface is available as it cools and congeals. The ensuing dark, resinous material then proceeds to create friction, flow resistance, and obstruction as it accumulates. In precision operations involving hydrostatic bearings and servo valves, this leads to placement and alignment errors that can range from annoying to catastrophic.
Removing varnish is one of the unsung attributes of the Hydra-Supreme filter element. In addition to removing very fine particulate and water, this filter also removes varnish from the oil, leaving the oil even cleaner than when it left the factory and greatly retarding the build-up of varnish inside the fluid system. It is important to note that even our filters cannot remove varnish that has already built up in an unprotected system. Once varnish has settled into place, it needs to be chemically or physically removed when it begins interfering with the function of the hydraulic or lubricating oil system.
HTI installed a Hydra-Supreme filter on the furniture manufacturer’s reservoir. We had them run the system as normal for a week without any other changes. The end of the week showed no valve failures, and the oil was noticeably clearer. They have now been producing furniture parts instead of scrap metal for 6 weeks and have had no valve or accuracy issues since. Everyone is happy, except the scrap metal dealer!