6 Misconceptions About Equipment Lubrication

Thread Content

Lubrication is of paramount importance in the daily management of mechanical equipment. Equipment lubrication is an effective way to reduce equipment wear, improve operational efficiency, and save materials and energy. However, in practice, many companies do not pay enough attention to this issue; in fact, there are many misconceptions, which ultimately result in certain economic losses. Some might say that I have been running a factory for over a decade, and I’ve used this same method when repairing equipment – without ever encountering any major problems. However, scientific management can effectively improve equipment efficiency, reduce maintenance costs, and enhance economic benefits. For equipment lubrication, understanding and avoiding these common misconceptions will make daily maintenance tasks much more efficient. Here are some common misconceptions regarding equipment lubrication – how many of these apply to you? I. 6 Common Misconceptions About Equipment Lubrication 1. Equipment lubrication means just adding oil. Many equipment managers in companies believe that as long as oil is added to the equipment’s oil tanks and bearings, there’s no need to worry about failures, and therefore it doesn’t matter what type of oil is used. As a result, there arose the phenomenon where machine oil is used for both gearboxes and bearing housings, and “grease” is added to bearings. Lubrication is not as simple as just adding oil; it is a science that makes use of fundamental theories such as fluid mechanics, solid mechanics, materials science, applied mathematics, and physical chemistry to study lubrication principles, lubricant materials, and lubrication methods, with the aim of controlling harmful friction and wear. Adding oil is merely one aspect of lubrication. 2. The more lubricant, the better? This is not true. Simply put, the purpose of lubricating equipment is to create a thin oil film between two friction surfaces, preventing direct contact between them and thereby reducing wear. However, considering certain side effects of adding lubricating oil, the amount of oil added must be strictly controlled. For instance, in reducers, in order to minimize resistance during gear motion and prevent excessive temperature rise of the oil, the depth to which the gears are immersed in the oil should be equivalent to 1–2 tooth heights; for high-speed applications, even less oil should be used. After the lubricant is added to the bearings, during its distribution, the heat generated exceeds the heat dissipated, causing the bearing temperature to rise. If too much grease is used, the resistance to rotation of the bearing increases, heat dissipation becomes difficult, which leads to higher operating temperatures for the bearing. Meanwhile, the high operating temperatures shorten the lifespan of the grease. Care must be taken not to fill the bearing chamber completely; generally, filling it to 1/3 to 2/3 of its capacity is sufficient. 3. Lubricants can be used interchangeably. The choice of lubricant depends on the operating conditions of the machine, the working environment, the specific characteristics of the friction surfaces, as well as the lubrication method; accordingly, the type and grade of lubricant used also vary. For equipment with high rotational speeds and a strong ability to create an oil wedge effect, lubricants with low viscosity should be used ； When the load per unit area on the friction surface of the equipment is high, a lubricant with high viscosity and good oiliness should be selected. When the operating temperature of the equipment is high, lubricants with higher viscosity, higher flash point, better oiliness, and greater stability, or greases with a higher dripping point, should be used. The smaller the gap between the friction surfaces of the equipment, the lower the viscosity of the lubricating oil that should be chosen ； The rougher the friction surface, the higher the viscosity of the lubricant that should be chosen; if grease is used, the working taper should be smaller ； In pressure circulation lubrication, where the oil temperature is relatively high, lubricating oil with higher viscosity should be used. The lubricants for different devices are selected strictly in accordance with the aforementioned principles and experimental results. Under normal circumstances, they cannot be used as substitutes; any attempt to do so will disrupt the lubrication environment of the equipment, leading to wear and damage to the machinery and resulting in financial losses. 4. It is fine to use lubricants together. Lubricants are petroleum products derived from oil and refined through various processes; different types and brands of lubricants contain different components in varying proportions. Generally speaking, lubricants should not be mixed together. To improve the physical and chemical properties of lubricating oil, a certain amount of additives must be added to it. The additives in various lubricants differ from one another; they include antioxidants, thickeners, oil-based additives, and extreme pressure additives. When lubricants of different types and grades are mixed together, chemical reactions may occur between the additives in the oil, resulting in the loss of their effectiveness and compromising the performance of the lubricant. 5. Frequent oil changes for equipment help prevent major problems. Changing the oil too often is not only a waste but also can hide existing equipment faults. To determine whether lubricant loses its usability over time, it can be assessed from the following aspects. (1) Viscosity testing usually involves comparing the lubricant already in use in the equipment with a lubricant of the standard viscosity specified for that equipment, in order to determine whether oil change is necessary. (2) Moisture test: Dip a clean, dry cotton thread into the oil to be tested and light it on fire; if there is water in the oil, an explosive sound and a flash will occur. (3) Inspection for mechanical impurities: Lubricants with low viscosity can be directly poured into a test tube, slightly heated, and then observed at rest. Oils with high viscosity can be diluted 5 to 10 times with clean gasoline, and the above method can be used to observe and determine whether oil replacement is necessary. (4) Identification of oxidation and deterioration: To determine whether the lubricant has suffered severe oxidation and deterioration, take the sludge at the bottom of the oil tank and rub it between the index finger and thumb. If a high amount of gum-like substance is felt and strong adhesion is observed, it indicates that the lubricant in question has undergone severe oxidation and deterioration. This method can be used to decide whether it is necessary to change the oil. (5) Presence of any changes in properties and presence of impurities: During equipment maintenance, assessing the quality of grease involves checking for any changes in its properties and the presence of impurities, which helps determine whether it is necessary to replace the grease. 6. Leakage is inevitable in equipment lubrication. Equipment leakage refers to the abnormal phenomenon where leakage occurs when it is not permitted according to the technical specifications of the equipment, or when the amount of leakage exceeds the limits specified by those technical specifications. Severe oil leakage not only causes oil shortages or outages, affecting the smooth progress of production, but also pollutes the surrounding environment. This not only damages the environment but also wastes lubricant. Lubricants are used for equipment lubrication, but this introduces the problem of oil leakage. However, people are not at a loss when it comes to equipment oil leaks; there are many methods and ways to prevent them. This requires operators to pay sufficient attention and possess the necessary skills in order to ensure proper equipment lubrication while also preventing leaks. II. Rationalization suggestions for equipment lubrication 1. Establish a reasonable lubrication system and standards for equipment lubrication. 2. High-performance lubricants should be used for equipment lubrication. By using high-performance lubricants, although the cost is higher, it can effectively reduce the frequency of equipment maintenance in actual use. 3. Be bold in innovating and making reasonable improvements to the original equipment’s lubrication design. Regular oil change management is simple, but the cost is high. Oil should be replaced based on its quality; regular monitoring of oil quality is required, which makes management a bit more complex. However, this approach prevents waste resulting from premature oil replacement and is in line with the principles of proper lubrication. Especially when high-quality oil is used, its service life is many times longer than that of lower-quality oils. 4. Use multi-stage lubricating oil to reduce wear. 5. Promotion of the use of solid lubricants. In practical applications, powders and films are used to reduce wear between gears, a process known as solid lubrication. A typical example of solid lubrication is embedded bearings, which offer advantages such as a long service life, high temperature resistance, and no pollution; moreover, no lubricating oil is required in actual operation. Equipment lubrication is an essential part of the daily maintenance of mechanical equipment. Only by having a proper understanding of equipment lubrication and carrying out lubrication in a scientific and appropriate manner can we ensure the normal and safe operation of the equipment, thereby effectively improving production efficiency and economic benefits.