Machinery Lubrication

Machinery Lubrication May - June 2018

Machinery Lubrication magazine published by Noria Corporation

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Page 45 of 80

www . | May - June 2018 | 41 Is it possible to load a grease gun but then not have the needed ammunition to complete the task? If the gun is not stored correctly, the same separation issues that can happen to a cartridge can take place after the grease is in the gun. Grease guns frequently end up at the bottom of a toolbox, lying on their sides. Not only is there a risk of damage to a device that can generate more than 10,000 pounds per square inch of pressure, but the conditions for leakage are created with the cartridge in this position. Although there is a lip seal against the inside of the cartridge, most guns are stored with spring pressure against the grease to feed it into the pumping mechanism. Separation occurs due to gravity and the spring pressure. e oil is then able to flow through the lip seal and to the end of the gun, where the rod exits the gun through a fairly large hole. Invariably, guns stored this way show evidence of this separation with puddles of oil in the toolbox drawer. Relea sing t he spring pressure reduces the separation but doesn't completely eliminate this effect. Some companies have improved the storage of their grease guns by installing racks from which to hang them. However, these installations often get one key consideration wrong. If the head of the grease gun, where the pump is located, is facing up, then the hole in the housing is facing down, allowing separated oil to escape. It takes a bit of modification, but if the grease guns can be stored with the head facing down, this path of leakage is nearly eliminated. How Long Will Oil and Additives Stay in Place within the Machine? If you have protected the grease in storage with good practices for both the cartridges and the grease guns, and have managed to get the grease into the machine in good condition, your considerations for gravity are not quite over. Greasing frequency is a function of multiple factors, including aging and oxidation stressors, the rate of contaminants fighting to reach the bearing through the grease, and the vibration the grease experiences, which places additional shearing stress on the lubricant to separate the oil from the thickener. Gravity is another contributor to limiting the life of the grease, as it is a constant downward pull on the grease or the separated oil. If the grease is in a sizable housing with a solid floor, such as in a horizontal shaft arrangement, the grease and oil will be pulled to the bottom of the housing and be retained. If the shaft is not horizontal, this force piles up grease against a sealing surface and increases the opportunity and rate that the grease can exit under oper- ating conditions. When calculating the "K" factors for grease relubri- cation frequency, shaft orientation is considered for this very reason. If gravity increases the rate of loss, the rate of replenishment must be stepped up to ensure there is always a supply of grease in the proper oil-to-thickener ratio to feed into the lubricated contacts. Grease is often the answer to the effects of gravity. When you have machines that need their lubricant kept close, grease is the choice. Frequently starting and stopping machines are normally designed for grease to counter the effects that gravity can have on an oil lubricant, pulling it down into the housing or reservoir and away from the lubri- cated parts. Even though grease does a better job of staying in place, it is still in a constant battle with gravity as it tries to separate the lubricant's components. Your job is to give the grease a fighting chance. is will help to ensure a constant grease supply and extend the life of your grease-lubricated machines. ML ML

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