Dry road to nowhere6/17/2023 ![]() Some thickeners have good reversibility, while others do not. This is referred to as mechanical wring-out. When grease is over-rolled by the bearing or gears, the oil can be rapidly separated from the thickener. Spherical roller bearings would be such an example. Some types of rolling-element bearings are more prone to oil separation. When the dropping point is reached, the bearing begins to bleed, the grease runs dry and eventually failure occurs. This bearing displays the results of high running temperatures commonly associated with over-greasing. The ultrasound technology measures friction in the bearing continuously-when grease is needed, the operator simply receives an altert on the cloud-based system and is given the option to lubricate the bearing with a push of a button.įigure 2. Devices like the UE Systems OnTrak SmartLube can help you avoid this issue by lubricating your bearings with the right amount of grease at the right time. Figure 2 shows an example of such a bearing. In such cases, the dropping point is reached, the bearing begins to bleed, the grease runs dry and eventually failure occurs. This is most commonly associated with over-greasing, causing high heat from churning. Too much grease in a bearing, mechanical conditions (misalignment, excess preload, etc.), and starvation can lead to high running temperatures. The copper prematurely oxidized the base oil in the grease, causing extreme thickening. The grease image in Figure 1 occurred at room temperature due to the high concentration of cupric catalytic metals in the grease from wear debris. The same transformation can occur with grease. Oxidized oil can take on the physical characteristics of roofing tar or even coal. The high concentration of cupric catalytic metals in the grease was from wear debris.īase-oil Oxidation. This grease image shows extreme thickening that resulted from copper prematurely oxidizing the base oil in the grease. At sufficiently high temperatures, oil can boil out of the thickener matrix, causing hardening of the grease over time (lower oil-to-thickener ratio and higher base-oil viscosity).įigure 1. Grease made from low-viscosity base oils is at the highest risk of volatilization. There are many classical examples of this, including the clashing of organic clay grease with soap-thickened grease. Accidental mixing of grease can lead to accelerated de-gelling and oil separation. This keeps the grease in an enclosed container until it is distributed, keeping particles out. To reduce this, consider using a single-point lubricator. This is when dust and particles come in contact with the grease as it is being dispensed in the bearing. ![]() A significant portion of this is maintenance-induced contamination. Gross contamination by dust, dirt, fly ash and similar dry-power contaminants can thicken the grease just like the introduction of a gelling agent. Once the causes are determined, we have the information necessary to prescribe steps to grease your bearings properly.Ĭontamination. ![]() Let’s begin by reviewing the primary causes of grease dry-out. In time, the grease can reach a state of consistency ranging from hard putty to sandstone, depending on the thickener type and degradation conditions.įrequently the most serious offending conditions leading to grease dry-out are aided by other causes working in concert. The elevated heat continues to force more rapid and complete drying of the grease. As grease becomes dry, frictional forces escalate, causing concentrated heat within the bearing. Often this takes years to develop, while in other cases the condition can reach catastrophic levels in just a few weeks. More serious is the hardened byproduct of oil drainage that builds inside the cavities of operating bearings and gears over time. We’ve also seen the dribble of oil from stored grease cartridges and prepacked bearings on storeroom shelves. We see conspicuous evidence of this when oil puddles in unleveled grease pockets in pails of new grease. We all know that oil has a natural tendency to drain out of the grease thickener over time. One of the main disadvantages of using grease over oil is the annoying tendency of grease to cake and dry out.
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