How to choose the right lubricating grease for construction machinery       

In the normal operation and operation of construction machinery, it is certainly inseparable from the grease, then how to choose and use, in order to maximize the protection of equipment, prolong service life, so as to better improve production efficiency? Today Xiaobian to tell you how to choose the engineering machinery going on right grease.

First, the main performance indicators of grease

The drop point refers to heating under specified conditions, when the temperature reaches a certain fluidity. The use of temperature it can be roughly determined lubrication points (drop point than the use of Qigao temperature 15~30 degrees)

Cone penetration: refers to the cone under the specified temperature and load in 5S vertical vertical penetration into the depth of grease (unit 1/10mm). It is a measure of consistency and lubrication flexibility.

Third, colloid stability (oil evolution): refers to the external force under the action of lubrication refers to the ability to preserve oil in the skeleton of its thickener, with the amount of oil to determine. When the amount of condensate oil grease over 5%-20%, which basically can not use grease.

The oxidation stability refers to the ability in storage and use in oxidation resistance.

The mechanical stability and consistency: refers to the ability to resist changes in mechanical working conditions. Mechanical stability, consistency decreased caused by grease.

The evaporation loss refers to under specified conditions, the loss of the total percentage. It is an important factor to influence the life of lubricating greases.

Sadly, water resistance: refers to the ability does not dissolve in water, does not absorb moisture from the surrounding medium and not by water to wash away the.

The similar viscosity: refers to the ratio of non shear stress and shear velocity of Newtonian fluid flow at. High speed low viscosity, high viscosity and vice versa.

Two. Failure analysis of lubricating grease

Failure caused by physical factors

Grease lubrication grease will also receive mechanical shear and centrifugal force in use under the action of being thrown out of the oil friction interface, resulting in the lubricant decreases, cone penetration decreases to a certain extent after hardening, grease will completely fail; in mechanical shearing, grease to structure damage (such as soap fiber separation or orientation) softening, consistency, caused by decreased and condensate oil increased, eventually leading to failure. Usually, the use of grease transmitting velocity 2000r/min, its life will be reduced by about half. Under high shearing stress, speed is doubled, the service life is only equivalent to the original life of 1/10.

Failure caused by chemical factors

Grease with oxygen in the air chemical anti Qing produce acidic substances, it is first in the consumption of antioxidant fat, but to a certain extent, the structure of organic acid will corrode the metal element and damage the grease, the drop point decline, base oil viscosity increase and poor liquidity. The results show that the higher the temperature, the grease life decreased more obviously. When the temperature is 90~100 degrees, the temperature increases by 19 degrees, the life of the grease decreases about half, and at 10~150 degrees, the temperature increases by 15 degrees, the life of the grease will also fall by half.

In addition, the use of grease in the environment of water, dust and harmful gas is also an important factor to deteriorate it. For example, the inclusion of copper, iron, lead, bronze and other wear particles in the grease will catalyze the oxidation of the ground grease. In a word, there are many reasons for the failure of grease, sometimes it may be caused by a certain reason, but more is the result of the interaction of many factors, or with a reason as a breakthrough, and then the other causes of interaction.

Three. Reasonable choice of grease

Friction should be taken into account when selecting grease

Working conditions (humidity, air temperature, air pollution, etc.) and working conditions (continuous operation, intermittent running, vibration and impact) and working environment (such as load, speed, temperature), working condition (continuous operation, intermittent operation, vibration and impact), etc..

The use of temperature, grease should be at least less than the drop point of 20~30

When the temperature is high, the grease with good oxidation resistance, little evaporation loss and high dropping point should be selected. When the temperature is low, the grease with low starting moment and similar viscosity should be selected, such as grease based on the oil.

The grease, the selected should be in accordance with the lubrication of speed is

In the high speed, low viscosity base oil should be used for cone penetration grease; for low speed grease, high penetration grade grease should be selected with high viscosity base oil.

Third, the grease should be commensurate with the size of load.

The heavy load, should choose the base oil of high viscosity, thickening agent with high content of lubricating grease. When the load is very large, the grease with extreme pressure additives or fillers (molybdenum disulfide and graphite) should be selected; when the middle and low load is used, grease with 2 consistency and short fiber structure and medium viscosity base oil is usually selected.

Fourth, the grease should be compatible with the use of environmental conditions

Contact with water in the air or humid environment, should be used as calcium, lithium, lithium complex base of water resistance grease; dust for a long time, should choose a thick (i.e., some brands of high fat), such good sealing, can prevent impurities mixed friction. In the environment of strong chemical medium should be used, such as synthetic oily fluorocarbon grease such chemical resistant grease.

Fifth, the selected grease should be matched with the friction pair for grease

A centralized grease, should choose 00~1 grease; for regular grease gun, grease cup grease filling parts, should choose 1~3 grease; for long-term use without change in fat position, should choose 2 or 3 grease.

The selected grease should be matched with the friction state

If the vibration is large when using high viscosity, adhesion and good vibration of fat, such as high viscosity naphthenic base lubricating oil or mixed thickener complex soap grease.

The grease should be selected and used to adapt to the

For lubricating fat according to the friction type, working conditions, work status, environmental conditions and grease the different ways and specific selection; for the protection of the fat, can effectively protect metals from corrosion, such as mechanical protection and water contact, should choose the adhesion ability, water resistance the ability of large aluminum base grease; general protection grease can be used solid hydrocarbon thickening high viscosity base oil made from fat. For sealing grease, we should pay attention to the performance of sealed medium solvent resistance.

S, the selected grease should try to ensure that reduce fat varieties, improve economic efficiency.

In order to meet the requirements, try to use lithium grease, complex soap grease, polyurea grease effect universal grease. In this way, the variety of the grease is reduced, the management of the grease is simplified, and the cost of the grease is reduced and the maintenance cost is reduced because of the long service life of the multiple effect grease.

Four, the correct use of grease

First, the amount of lubrication should be appropriate

If the amount of grease added is too large, the friction torque will increase, the temperature will rise, and the grease consumption will increase; but when the amount of grease is too little, the dry friction will not be obtained. Generally speaking, the appropriate amount of grease for total void volume in the bearing 1/3~1/2. But according to the situation, sometimes in bearing grease lubrication and the edge of cavity.

Second, pay attention to prevent the mixing of different types, grades and old grease

Avoid the cross use of grease container and tools, otherwise, the drop point of grease will be decreased, cone penetration and mechanical stability will decrease.

Third, pay attention to the replacement of new fat work

Because of the variety and quality of grease are constantly improving and change, instead of old equipment new grease, should be tested first, before the formal trial use; in the replacement of new fat, should first remove the waste grease, the parts clean. In addition the grease, should waste grease extrusion, see the new grease grease discharging port so far.

Fourth, attach importance to the management of filling grease process

Before receiving and filling grease, attention should be paid to the cleaning of containers and tools. The grease mouth on the equipment should be cleaned in advance so as to prevent the mixing of mechanical impurities, dust and sand.

Attention should be paid to the timely replacement of season grease

If the equipment in the environment in winter and Xia Li and temperature changes, if the summer use of winter fat or on the contrary, the results will be counterproductive.

The add in grease regularly.

Grease replacement time should be based on the specific use of the situation, not only to ensure reliable lubrication, but not cause grease waste.

Sadly, don't use wood or paper containers packaging grease

Prevent oil loss, hardening, mixing with water or contaminated, and should be stored in a cool and dry place.

Details determine success or failure, do not think reasonable choice of grease is only a small matter, pay attention to details is to accumulate wealth.