What is the difference between grease lubrication and oil lubrication?

I don’t understand; I’ll search for it for you on Baidu: http://wenku.baidu.com/link?url=VbFEkkbN32Mvj3bhXT0HNiv-_m1YS3A6xbERrxAwlFNW9WsQsj53C8b8_D2qEOKDJozPT2Vf8WlwgthwWKlcALQDGIqiaGrX93RrAw4qzXG http://baike.baidu.com/link?url=PQ3lH1fYFrNFg_Aq8LSIqnHJ8SpzMb4oWT3UZ3StqdZ9kgED4tw-H_gn24SO-VWpeLzLeuSLXV68y1yypnvAEK. Search term: Grease is a type of lubricant to which thickeners have been added; it is commonly used for lubricating bearings. Grease is made by combining different soap bases with an appropriate amount of lubricating oil, depending on its intended use; it can be thought of as a sponge saturated with lubricating oil. The main purpose of both lubricants and greases is lubrication, but greases are more suitable for lubrication in conditions such as low speeds, wide temperature ranges, harsh environments, and long oil change intervals. Lubricating oil is a liquid lubricant used in various types of machinery to reduce friction and protect the machinery as well as the components being processed. Its main functions include lubrication, cooling, rust prevention, cleaning, sealing, and cushioning.

Differences between grease and lubricating oil: 1. Adhesion – When the friction surfaces are at rest, grease can maintain its original shape; it does not flow away due to gravity, nor does it slide down vertical surfaces or drip out through gaps. This feature is highly suitable for friction areas that operate intermittently or not frequently, for areas where it is very difficult to supply lubricant (such as the lubrication points in overhead cranes), as well as for open or poorly sealed areas. When the friction area is in motion, grease does not get flung out due to centrifugal force like lubricating oil, nor does it splash out from areas with poor sealing. Some oil dripping or splashing can be almost completely avoided, thereby ensuring that the environment is not or is only minimally polluted, and also preventing contaminated products from being produced. This is particularly important for industries such as papermaking, textiles, and food processing. 2. Operating temperature range: The operating temperature range for greases is wider than that for lubricants. For example, general-purpose lithium-based greases can be used in a temperature range of –20 to 120°C, while calcium-based or sodium-based greases can generally also be used at temperatures ranging from –20 to 60°C or from –20 to 120°C. However, a certain grade of lubricant has a much narrower temperature range of use. 3. Pressure resistance: Grease has a much greater adsorption capacity on metal surfaces than lubricants, and it can form a relatively strong oil film that is capable of withstanding higher working loads. This is due to the presence of large amounts of polar substances in grease. Furthermore, when used as a base oil and polar additives are added, its sensitivity is also better than that of lubricating oils. 4. Service life: When lubricant is used for an extended period without being replaced, it can still fulfill its lubricating function, as it is only the small portion of lubricant located near the friction surfaces that actually provides lubrication; moreover, circulation of lubricant is facilitated by the soap fibers, which means its service life is quite long ； Lubricating oil, on the other hand, needs to be added frequently or supplied in a circulating manner; otherwise, proper lubrication of the machinery cannot be ensured. In terms of quantity, the consumption of lubricating oil is 15 to 20 times higher than that of grease; therefore, there are many more parts that are lubricated with grease than with lubricating oil. In areas such as automotive lubrication points, grease is used in over 2/3 of the cases. On the other hand, since refueling is not frequent, the maintenance period is long, consumption is reduced, and thus maintenance costs are also low. 5. The design of lubrication equipment: Equipment that uses grease for lubrication has a simpler structure, which allows for simplified design and reduced costs. Furthermore, the lubrication system occupies a relatively small area, and the placement of lubrication points is highly flexible. Once it is put into operation, it can also help reduce maintenance and management costs. Some precision instruments, meters, and electronic devices have such a small internal space that it is not possible to install a dedicated lubrication system; therefore, they require long-lasting lubrication, often relying on grease for life. Lubricating oil, on the other hand, needs to be used in a closed system; the equipment that requires lubrication is also quite complex, and it involves high investment costs and requires a large amount of space, making it unsuitable for use in semi-closed or open lubrication applications.

This post was last edited by qugd on 2015-7-5 at 18:45. It is recommended that the original poster first understand the differences between lubricants and greases, as well as the situations in which they are used. Lubricants are based on mineral oil or synthetic oil as the base oil, with specific additives added to meet the requirements of the application for which they are intended. It has good fluidity and is used for lubricating mechanical components that operate at relatively high speeds; it also serves functions such as cleaning and cooling. It is commonly used in rotating machinery and high-speed reciprocating machinery. Lubricating grease is thus based on synthetic petroleum grease or biological oils, with additives having specified properties added to it. It has poor fluidity during use; it is applied to mechanical components that move at low speeds, serving both to lubricate and to isolate and protect those components. Generally, translational machinery and gear or rack drives are used more frequently. There is a general rule regarding the lubricants or greases used in mechanical lubrication: high-flow lubricants are used for high-speed machinery, while low-flow greases, or even greases with no flow properties at all, are used for low-speed machinery. For ultra-high-speed moving machinery, even air bearings are used, with an air gap film serving as the lubricating medium to achieve a contact-free state between the mechanical components.

Grease is a dry oil, consisting of an oil base + additives + thickeners. Lubricating oil is a light oil, composed of base oil + additives. Dry oil, that is, grease, is generally used in applications where sealing is not required, such as bearings and rollers; while thin oil, that is, lubricant, is used in applications that require sealing, such as hydraulic stations and gearboxes.

There is a difference between lubricants and greases; choose the appropriate lubricant based on specific requirements