Choosing the right grease for a crossed roller bearing is essential for its performance, долголетие, и надежность. The wrong grease can lead to premature failure, excessive friction, and heat generation. The selection process depends on several critical factors related to the bearing’s operating conditions.
Key Factors for Grease Selection
Operating Temperature: This is one of the most important factors. The grease must be able to perform effectively within the temperature range of the application.
Вязкость базового масла: The viscosity of the base oil (the lubricant component) changes with temperature. It’s crucial that the base oil maintains sufficient viscosity at the operating temperature to form a protective lubricating film.
Dropping Point: The dropping point is the temperature at which the grease changes from a semi-solid to a liquid. The operating temperature should be well below the grease’s dropping point (typically by 10-20°C for mineral greases and 20-30°C for synthetic greases).
Types of Grease: Different thickeners and base oils are suited for different temperature ranges. Например, synthetic greases are often used for extreme high or low temperatures.
Loads: The load on the bearing determines the required film strength of the grease.
High Loads: Applications with heavy or shock loads require grease with a higher base oil viscosity and, often, with Extreme Pressure (Эп) additives. These additives create a protective layer to prevent metal-to-metal contact under high pressure.
Low Loads: For lighter loads, a lower viscosity grease is generally sufficient.
Скорость (Rotational Speed): The rotational speed of the bearing is a key factor in selecting both the base oil viscosity and the grease consistency (NLGI grade).
High Speeds: High speeds generate more friction and heat. A lower viscosity base oil and a softer consistency grease (lower NLGI number, например, NLGI 1 или 2) are typically used to minimize friction and allow for better heat dissipation.
Low Speeds: Very low-speed applications with heavy loads may benefit from a higher viscosity base oil and a stiffer grease (higher NLGI number) to ensure the lubricating film is maintained.
Среда: The operating environment can introduce contaminants or moisture that affect the grease’s performance.
Dust and Contaminants: Grease acts as a sealant to prevent contaminants from entering the bearing. A stiffer grease (higher NLGI grade) is often better for this purpose.
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More detailed information on how to choose grease for crossed roller bearings can be found at:https://www.prsbearings.com/a/news/grease-selection-for-cross-roller-bearings.html
