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Lubricants

Lubricants

Lubricants are substances that have a lubricating effect. They are used for lubrication of rubbing parts of machines and devices, as well as in the processing of metals by pressure. As lubricants, liquid oils of predominantly petroleum origin, synthetic oils, greases, solids (graphite, molybdenum disulfide, polymers with fillers), gaseous substances (air, hydrocarbon vapors, halogenated methane derivatives, etc.) and surfactants ( soap, glycerin, etc.). According to the state of aggregation, properties and purpose, they are divided into groups and varieties.

Progress is moving forward by leaps and bounds, new mechanisms, improved equipment appear, the maintenance features of which sometimes differ somewhat from the care of equipment that is familiar to technical specialists of enterprises, but somewhat outdated. Misconceptions about lubricants that have been held by some technicians for decades have fueled a host of myths and misconceptions that do not reflect the characteristics of modern lubrication technology. Our goal is to dispel the most common myths about industrial lubricants.

All lubricants are one face. Lubricants by and large perform one function, but there are still significant differences between them. Some are quite obvious (viscosity, color, etc.). Other, no less significant, qualities cannot be determined "by eye", but should be taken into account when choosing the right lubricant. It should be remembered that each of the hundreds of industrial lubricants contains additives specially blended for a specific application. It is the use of an unsuitable lubricant that can cause the failure of mechanisms, while the use of a lubricant with the right qualities contributes to an increase in the efficiency of the machine and prolongation of the life of the equipment.

Pennsylvania oil is the best raw material for lubricants. This opinion was quite true at a time when the process of separating the lubricant base from the crude oil was rather complicated, and it was from Pennsylvania crude oil that it was possible to obtain a raw material with a relatively high corrosion resistance and a high viscosity index. But nowadays, many oil companies use technologies that make it possible to obtain the same quality base components for the preparation of lubricants from various types of crude oil (by changing the set of additives).

Oil cannot be produced. Operating temperatures above 65 ° C oxidize the oil and may thicken. After a while (the duration of which depends on the quality of the oil and the operating temperature), a film forms on the equipment - traces of lubricant sediment. To avoid this, you should periodically change the oil in the mechanisms (once every six months or once a year - depending on the temperature at which the equipment is operating).

The main cause of equipment failure is old oil. This is not entirely true. More often equipment breaks down either when the wrong lubricant is used, or if the lubricant contains a high concentration of contaminants (especially dirt and metal particles that cause premature wear and damage to mechanisms).

To choose the right lubricant, it is enough to have information about its physical characteristics, information about additives is insignificant, you can not pay attention to it. Lubricants are manufactured by oil companies to specific standards, but it is impossible to tell by color, flash point or density, what advantages or disadvantages a given lubricant has, what is the intended use, etc. It should be taken into account that it is precisely the additives that increase the efficiency and extend the life of the lubricant, due to them the pour point decreases and the temperature range for maintaining a sufficient viscosity of the lubricant expands. In addition, additives prevent foam formation, control oxidation, prevent sludge and film formation, and reduce frictional wear (this should be borne in mind when conducting standard equipment tests, the results of which may be distorted due to additives).

Viscous oils have the best lubricating properties. Indeed, it is viscous oils that can form thick lubricating films. However, it should be remembered that, thanks to some additives (for example, sulfate and metal additives), the lubricating properties of oils increase without increasing the viscosity.

If the viscosity of the oils is the same according to SAE or ISO, then they are interchangeable. This is not true. It should be remembered that SAE and ISO numbers can only help you select a lubricant with a certain level of viscosity, they do not imply any other characteristics. For example, hydraulic oil cannot be replaced with engine oil, although SAE lubricants are in the same viscosity grade.

More viscous oils have more insoluble impurities. In modern lubricants, detergents or dispersants help to retain a significant volume of insoluble impurities in fine, homogeneous particles. These particles are distributed throughout the volume of the oil in such a way as to minimize the risk of sludge or harmful sludge formation. As a result, a lubricant with a fairly high viscosity level contains a minimum amount of potentially harmful insoluble impurities.

The acidity of the oil corresponds to the acid number. It should be remembered that in most oils, due to metal additives, the acid number is higher than the acidity of the lubricant itself. If the acid number increases during operation, this may indicate that the oil has acquired corrosive properties or that contaminants and non-corrosive wear products have entered the lubricant.

By examining the ash content, you can get information about the presence of abrasive components in the oil. Indeed, some metal additives can form non-abrasive ash, which, in fact, does not contain any information about the oil itself. To detect abrasive components, the oil must be driven through a fine filter disc (5 microns) and the sediment examined with a magnifying glass. A more detailed quantitative and qualitative analysis of the identified abrasive components can be carried out using spectrophotometry and only under laboratory conditions.

Conradson Coke Residue (CCR) information is extremely important. Indeed, this test, designed to measure coke residue in a steam cylinder lubricant, was very important at a time when fully absorbable components were digested (residue was measured during tests). But since the oil is not digested in the process of using modern lubricants and the reason for the appearance of carbonaceous deposits is most often the aging (or contamination) of the oil, the CCR test has lost its former significance.

High specific gravity oils have low oxidation stability. This is not the case when it comes to modern lubricants, the stability of which is increased by the use of more advanced technologies in refineries and the use of additives that increase the resistance of lubricants to oxidation.

The pump can receive and move oil through the system at a temperature not lower than the pour point. Not necessary. After all, the pour point (at which the lubricant acquires maximum viscosity, on the verge of solidification) is determined in laboratory conditions. During testing, the oil delivery head is approximately 25% in. This should also be taken into account (after all, in operation it can be higher or lower than the test one).

The oil is intended only for lubrication of mechanisms, it has no other functions. In addition to the aforementioned function, the oil dissipates heat, prevents contaminants from entering the bearing seals, washes away dirt and wear particles (takes them to the filters of the mechanism).

The more lubricant, the better the mechanism will work. Misconception. It should be remembered that, for example, applying too much grease to the seals can destroy them (as a result, contaminants can enter the mechanism), and in the bearings of electric motors can penetrate the winding and lead to the combustion of the motor. Bearings from excessive lubrication overheat (as the fluid resistance increases) and fail, in addition, heating reduces the life of the oil, etc.

Hydraulic oil is of the lowest quality. The oil used for power transmission and lubrication of hydraulic pumps, bearings, cylinders, etc., must be wear-resistant, oxidation-resistant, provide a high level of protection for the pump motor, etc. Therefore, hydraulic oil is a good quality lubricant.

If the oil is fire resistant, it will not ignite. Unfortunately, this is not the case - fire-resistant hydraulic oils still burn, but only as long as there is a fire, and immediately after the fire has been removed, the combustion stops (while ordinary mineral oil, after removing the fire, continues to burn until extinguished). In addition, flame retardant hydraulic oil is much more difficult to ignite than petroleum based lubricants.

A good technician can evaluate the quality of a lubricant by taste, smell, etc. This was true when many types of lubricants were manufactured for specific applications. Indeed, their consistency (sticky, soft and homogeneous, etc.), taste and smell could easily be discerned for a specialist. But modern lubricants, created for complex use, are almost all soft, oily, short-fibred, and even an experienced person is not always able to determine "by eye" how high-quality lubricant is in front of him. The taste of such materials is usually disgusting and by no means harmless to the body, therefore we strongly recommend using safer methods for evaluating oils.

The anti-seize agent (EP) in the lubricant is molybdenum disulfide. Remember that the EP must react with the lubricating surface to form a film. Molybdenum disulfide, which is just a grease, does not cause this effect.

Water does not penetrate into a water-repellent grease. Indeed, only after absorbing water does the lubricant begin to repel it. Water-repellent grease does not lose its consistency by absorbing water. Other lubricants (for example, sodium) that do not have water repellency become softer during absorption. After a while, this grease is finally liquefied and washed out.

The highest quality grease has the highest dropping point. Not. Greases with high dropping points can be used at higher temperatures, this indicator does not provide information about the quality of the grease.

The manufacturer must indicate the requirements for the use of lubricants in the mechanism guarantee. Unfortunately, this information is not always included in the warranty. Therefore, before changing the lubricant, you should consult with the manufacturer (especially if the warranty period has not yet expired).

Any employee can carry out lubrication work. After all, one should not only comply with the lubrication schedule of mechanisms, which any employee is really capable of. It should be noted that an experienced lubricant technician who knows well the mechanisms with which he works is able to notice the problem at the initial stage by various signs (overheating, sounds, sudden changes in smell or color), which will not tell the amateur about anything.

Lubrication is expensive. Maybe, but the cost of downtime or damage to expensive equipment due to unsystematic or careless lubrication practices will be even more expensive.

The total cost of lubricants is almost equal to the cost of lubricants. Alas, this is not the case. The ratio between the cost of lubricants and the cost of their use is approximately 1: 5 (after all, the payment for the work of a technician, controller, transportation, storage, etc. should be taken into account).

You won't save much on lubricants. With the correct use of lubricants that are most suitable for the given machinery and the given mode of operation, effective maintenance, cleaning or filtering of the lubricant can significantly reduce oil consumption. Savings in some cases are thousands of dollars (for example, switching to a premium long-life grease generated $ 33,000 in revenue for a steel fabricator in one year).

Watch the video: Lubrication basics (October 2020).