FUNDAMENTALS
Edited by Mary C. Gannon ⢠Editor
How does heat affect a hydraulic system? Everyone knows that contamination can be catastrophic to a hydraulic system. But heat can also be detrimental to hydraulic fluid and the components within that system. Heat contamination reduces oil viscosity, which in turn reduces the fluidâs ability to lubricate components. This thinning of the oil causes surface-on-surface wear. Without proper viscosity levels, as components rub against each other â such as a wear plate and the slippers on a piston pump â they wear at accelerated rates. This wearing also softens metals, which in turn increases the rate of wear. For example, anywhere thereâs metal rubbing on and near to other pieces of metal (even if itâs two different materials such as bronze or stainless) as the metal heats up, it becomes softer and it wears away more quickly. This problem is exacerbated if other forms of contamination are present. Additionally, heat can break down system seals. As they break down, flecks of rubber can enter the system, causing internal contamination. And, if a seal fails, external contamination will easily enter through cylinder rods.
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Heat contamination also changes the chemical properties of hydraulic oil. It can reduce the additives in the hydraulic oils, increase sludge and also accelerate oxidation. It actually changes the nature of your oil, making what may have been a suitable oil a poor choice for your system. Heat enters a hydraulic system in multiple ways. One culprit is ambient heat. For example, you may have a blast furnace dipping molten metal into a ladle. It is imperative that the hydraulic actuators and the oil used within them are designed for that type of environment.
Excessive system heat can cause hydraulic fluid to break down, resulting in lost viscosity, thinner fluid, and more damage that can cause catastrophic failure to internal components, such as this piston slipper pad or these pistons. | Image courtesy of Panolin
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2/15/19 1:02 PM
