How to choose the right lubricant

How to choose the right lubricant

Lubrication system is a system that supplies lubricant to the friction points of the machine or unit, including the requirements, alarms and monitoring of the parameters and faults for the transportation, distribution, adjustment, cooling and purification of lubricant and its pressure, flow and temperature The whole set. In the lubrication work, according to the actual working conditions of various equipment, the rational selection and design of its lubrication method, lubrication system and device are very important to ensure that the equipment has a good lubrication condition and working performance and maintain a long service life. significance.

Generally speaking, the lubrication system of mechanical equipment should meet the following requirements:

1) Ensure that lubricants of a certain pressure are supplied to each lubrication point evenly and continuously, with sufficient oil volume, and can be adjusted as required.

2) High working reliability. Adopt effective sealing and filtering devices to keep the lubricant clean, prevent dust and moisture in the external environment from entering the system, and prevent pollution of the environment due to leakage.

3) Simple structure, as standard as possible, easy maintenance and high-speed adjustment, easy to check and replace lubricant, low initial investment and maintenance costs.

4) With working parameter indication, alarm protection and working condition monitoring device, it can find lubrication failure in time.

5) When the lubrication system needs to ensure a suitable lubricant working temperature, cooling and preheating devices and heat exchangers can be added. When designing the lubrication system, three kinds of lubrication elements must be considered, namely: ① type of friction pair (such as bearings, gears, guide rails and other supporting elements) and its operating conditions (such as speed, load, temperature and oil film formation mechanism, etc.); ② The type of lubricant (such as lubricating oil, grease or solid, gas lubricant) and their performance; ③ The type of lubrication method and oil supply conditions, etc. 1. Classification of lubrication systems and methods 1) Classification of lubrication systems and methods There are many types of lubrication systems and methods currently used in machinery and equipment. Generally, there are two major types of decentralized lubrication systems and centralized lubrication systems according to the use and advantages of lubricants. At the same time, these two types of lubrication systems can be divided into two types: full loss and circulating lubrication. In addition to the above classification, according to the type of lubricant supplied, the lubrication methods can be divided into lubricating oil lubrication (or thin oil lubrication), grease lubrication (or dry oil lubrication), solid lubrication, and gas lubrication. (1) Dispersed lubrication It is often used to lubricate scattered or individual parts of lubrication points. In its lubrication, it can also be divided into two basic types: full loss (or "one-time oil lubrication") type and circulation type, such as the use of portable fueling tools (oil pots, oil guns, hand brushes, chlorosol spray guns, etc.) Oil, grease nipple, oil cup, rail surface and other lubrication points are manually lubricated, as well as oil rope or oil pad lubrication, splash lubrication, oil ring or oil chain lubrication, etc. (2) Centralized lubrication Use a complete set of oil supply devices to supply oil to many lubrication points at the same time. It is often used for the lubrication of gearboxes, feed boxes, complete or complete sets of mechanical equipment and automated production lines. The centralized lubrication system can be divided into three types of systems: manual operation, semi-automatic operation and automatic operation according to the way of oil supply. At the same time, it can be divided into a total loss system and a circulation system. After the lubricant is sent to the lubrication point, it is no longer recycled and recycled. It is often used for lubricant recovery with or without recovery. The oil requirement is very small and it is difficult to place the oil or Oil sump occasions. The lubricant in the circulating lubrication system is sent to the lubrication point for lubrication and then flows back to the oil tank for recycling. The static pressure lubrication system is a system that uses an external oil supply device to deliver lubricant with a certain pressure to the static pressure support for lubrication. 2) Types of centralized lubrication systems Centralized lubrication systems are the most widely used systems in machinery and equipment. There are many types, which can be roughly divided into the following 7 types: (1) Throttle type uses fluid resistance to distribute lubricant, and the distributed lubrication The dosage is proportional to the pressure and the size of the orifice, the oil supply pressure range is 0.2 ~ 1.5MPa, and the lubrication point can be as much as 300 or more. (2) Single-line lubricant is sent to the fuel injection nozzle through the main line of the single line under intermittent pressure (direct or delayed), and then sent to each lubrication point. The oil supply pressure ranges from 0.3 to 21 MPa, and the lubrication point can be as much as 200 or more. (3) The two-line lubricant is sent to the quantitative distributor through the two main lines that alternately change the flow direction by a directional control valve under the pressure, relying on the alternating lift control of the lubricant pressure in the main line distributor, leading the main line Alternate lifting of the middle lubricant pressure operates the quantitative distributor, so that the quantitative lubricant is supplied to the lubrication point. The oil supply pressure range is 0.3~40MPa, and the lubrication points can be up to 2000. (4) Multi-line multi-head oil pumps have multiple outlets each with a pipeline to directly deliver a fixed amount of lubricant to the corresponding lubrication point. The layout of the pipeline can be parallel or series installation. The oil supply pressure range is 0.3~40MPa, and the lubrication points can be up to 2000. (5) Progressive type The quantitative distributor is operated by pressure rise and fall to send lubricant to each lubrication point according to a predetermined progressive program. The oil supply pressure range is 0.3~40MPa, and the lubrication points are more than 800. (6) Oil mist/oil-air type Oil mist/oil-air lubrication is a lubrication method in which compressed air and lubricating oil are mixed and condensed by a condensing nozzle or nozzle and appear as oil mist or fine oil droplets sent to the lubrication point. The oil supply can be adjusted. The lubricating oil can contain suspended oil mist in the compressed air, which pollutes the environment. If necessary, the exhaust device can be used to remove the exhaust gas. When using this lubrication method, compressed air that has been dewatered and purified must be used. At the same time, it is best to add antioxidant additives to the lubricating oil. The difference between oil mist and oil-air lubrication is that the oil particle size of the former is 1 to 3 m, while the oil particle size of the latter is 50 to 100 m. It is usually in the form of tiny oil droplets, and its transportation distance is much shorter than the former. (7) Hybrid lubrication system composed of the above-mentioned lubrication system. 2 Principles of selection of lubrication system When designing the lubrication system, a comprehensive analysis of the lubrication requirements of each part of the mechanical equipment should be made to determine the type of lubricant used and try to Reduce the types of lubricants and lubrication devices. Under the condition of ensuring good lubrication of the main components, comprehensive consideration of the lubrication of other lubrication points should ensure the quality of lubrication. The lubrication system should not only meet the need for lubrication during the operation of the equipment, but also adapt to the working conditions and use environment of the equipment, so as to avoid inappropriate friction, temperature, noise and premature failure. The oil supplied by the lubricating system should be kept clean to prevent the intrusion of external dust and the like to cause pollution and damage to the friction surface, and improve the reliability during use. The main components of a complex lubrication system, such as pumps, distribution valves, and filters, should be properly combined and standardized as much as possible to facilitate access to maintenance and cleaning, reduce equipment operation, repair and maintenance costs, and prevent personal and equipment safety accidents. When choosing a lubrication system, we must pay attention to the degree of automation and reliability of the system, pay attention to the installation of instructions, alarms and working condition monitoring devices to predict and prevent early lubrication failures to improve equipment operation rate and service life.