High-temperature grease is a lubricant applied to equipment operating at high heat levels. Such greases can resist degradation in the presence of hot temperatures and heavy loads while providing ideal lubrication, enhanced wear resistance and performance, and increased uptime and longevity for machinery components like bushings and bearings. Choosing the right grease for a project requires knowledge of working temperature conditions, the chemistry of thickeners and additives, grease compatibility and degradation, and relubrication needs.
High-Temperature Grease Explained
The concept of “high-temperature operations” does not refer to one universal maximum temperature. For example, steel mill bearings must operate in continuous temperatures as high as 149° C (300° F), while drying ovens for curing surface coatings operate at approximately 204° C (400° F), and they both fall under the category of high-temperature applications.
High-temperature greases are made up of a balance of base fluids, thickeners and additives. Their price per pound typically goes up in correlation to a specific grease’s operational temperature range. It’s the lubricant’s composition that dictates the ideal operating temperature, viscosity, stability and related properties.
High-temperature operating environments and hot equipment will cause any grease, including high-temperature grease, to degrade over time due to thermal stress. Oxidative failure, another concern when grease is exposed to air, is exaggerated as temperature increases. Machinery requires lubrication periodically to ensure optimal performance.
While trying to select a high-temperature grease leaves much to consider, there are multiple selection criteria used to help identify the right base fluid to achieve the needed performance characteristics, as well as the necessary composition of thickener and additives to maintain stability and balance in a high-temp grease mixture.
Selecting a High-Temperature Grease
To effectively choose the right high-temperature grease, ask the following:
- What is the ambient temperature of the environment where the equipment being lubricated is operating? Is it possible to measure the temperature of the component being lubricated?
- If the maximum operating temperature is known for the equipment, is it continuous or intermittent?
- During the equipment’s operational and non-operational intervals, is it exposed to heating and cooling cycles?
- Will the chosen grease be appropriate for the speed and load capacity of the equipment?
- Are there atmospheric contaminants in the equipment’s operating environment that could be incompatible with certain grease types?
- What base fluid type and viscosity are best for the equipment?
- What thickener type would be best considering the temperatures and base fluid type selected?
- What additives and additive characteristics are best to enable optimal grease performance?
- What are the appropriate lubrication intervals for the machinery and does that fit with the processes it is performing?
High-Temperature Grease Compatibility
It’s vital to determine the compatibility of a high-temperature grease mixture before grease selection to ensure ideal performance and maintain the proper chemical balance. It is easier to evaluate compatibility before exposing the grease to high temperatures and only then discover the grease in service is incompatible with the one considered for replacement. Often, relubrication intervals can be used to address compatibility problems by flushing the original product until the incompatibility issue is resolved.
Additionally, grease compatibility can be determined by doing the following:
- Review the compatibility chart. Each type of grease usually has an accompanying compatibility chart to help determine the proper thickener to use.
- Run grease compatibility testing. Prepare mixtures of the current grease with the replacement at 10:90, 50:50, and 90:10 ratios. Raise the temperature of the grease mixtures to those thermal conditions expected in the operating application for a specific interval. Afterward, test for modifications to four-ball wear performance, penetration stability, and any other noticeable abnormalities.
- Check the compatibility properties. Grease can be mixed to determine compatibility by evaluating whether it becomes a softer consistency, heat resistance is reduced and it melts more easily, and additive performance still provides good equipment protection.
High-Temperature Grease from Lubrication Engineers
High-temperature grease is critical for effectively lubricating equipment operating under high-temperature conditions. Choosing the best grease for the specific application will help optimize machinery performance and prevent failure of bearings, bushings, gears, slides, and more.
Since 1951, Lubrication Engineers, Inc. has formulated and manufactured an extensive, versatile product line of high-performance industrial greases, including high-temperature and extreme-pressure varieties designed to outperform standard options. To suit industries worldwide from automotive to food and beverage, LE offers industrial greases in various NLGI grades, with a variety of thickener types, and proprietary additives.
To learn more about our various product offerings and the best choice for your unique high-heat application, contact us today.
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