Putting the simple back into viscosity
Written by John Sander
Conclusion
Lubricant viscosity or consistency is a physical measurement of a lubricant's internal resistance to flow. It can truly affect how the lubricant will function in a piece of equipment. Fortunately, organizations like ASTM, SAE, AGMA, ISO and others have created standards for lubricant viscosity and consistency that are to be used as guidelines when selecting the proper lubricant. If the wrong lubricant viscosity is selected for an application, the chances for equipment failure are dramatically increased. Therefore, the best rule is to always check the original equipment manufacturer's manual for lubricant viscosity recommendations.
If the OEM makes no recommendations, then the next step is to consider the operating speed, temperature and load of the application to be lubricated. Finally, after making a lubricating product selection, it is important to closely monitor the equipment to ensure the right choice was made. If possible, visually observe the moving parts to verify that a sufficient lubricant film is present to protect them. If not, listen for any unusual load grinding, chattering or squalling noises, which often are indications of metal-to-metal contact. Finally, one last technique is to contact lubricant manufacturers for recommendations. They often can provide technical support for proper fluid or grease selection.
Very simplistically, viscosity is a measure of a lubricant's physical resistance to flow, yet it is probably the most important property of a lubricant.
