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Routine Inspection And Maintenance Of Iko Plastic Bearings
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Storage And Use Of Grease

Use Of Grease

There are many kinds of lubricating greases, many brands, and different performances. Grease is more perishable than oil, and it is difficult to deal with impurities mixed in the grease. Therefore, it is of great significance to strengthen the quality management in the storage of lubricating grease.

  1. After long-term storage, the quality of lubricating grease will change in the following aspects:
  2. Color changes;
  3. Mixed with dust, sand, dust and other mechanical impurities;
  4. To stir or absorb water:
  5. After long-term storage, lubricating oil precipitates and forms hard lumps, resulting in unqualified oil and soap separation, acidification, and corrosion.

Reasons for deterioration use of grease during

The introduction of impurities and moisture from the outside; physical or chemical changes in the oil itself.

Measures to delay the deterioration of lubricating oil during storage:
  1. Lubricating grease should be stored first to reduce the influence of temperature, moisture and dust; lower the storage temperature; strengthen targeted management according to the characteristics of different types of lubricating grease; pay attention to sealed storage;
  2. Pay attention to the cleaning of degreasing tools and containers; use large, medium and small packages for different users; pay attention to regular inspection of lubricating grease in stock.
Storage And Use Of Grease

Main Failure Mode

Oxidative deterioration, destruction of lipid colloidal structure, separation and loss of grease, mixing of foreign matter, aging of grease (hardening, loss of lubrication)

A failure occurs when one of the following conditions is met:
  1. When the consistency changes to ± (15-20)%, it is generally necessary to replace the grease;
  2. If the dropping point changes, the judgment of soap-based grease aging failure is as follows: lithium-based grease below 140°C, sodium-based grease below 120°C, calcium-based grease below 50°C, aluminum compound below 180°C, lithium compound below 200°C,
  3. Others, the change is greater than ±20%, the acid value of the lubricating oil exceeds 3mgkoh/g and it will fail, the mechanical impurity content is below the unqualified, iron> 1%, or copper> 3%, or the change rate of ash> 50%

Lubricating Grease Failure Analysis

  1. failure caused by physical factors
    In use, the grease will be subjected to mechanical shear force and centrifugal force at the same time, and the grease will be thrown out due to friction, wiping the interface and making it separate from the oil, resulting in reduced usage of grease, reduced cone penetration and hardening. At a certain point, the grease will fail completely;
  2. Under mechanical shear, the structure of lubricating grease is disrupted (such as soap fiber separation or orientation), resulting in softening, loss of consistency and increased oil separation, which eventually leads to failure. Under normal circumstances, if the transmission speed of grease is increased by 2000r/min, its service life will be reduced by about half. Under high shear stress, the speed is doubled, and the service life is only one-tenth of the original life.
  3. failure caused by chemical factors
    Lubricating grease reacts chemically with oxygen in the air to produce acidic substances. First, it consumes the antioxidant additives in the grease. But to a certain extent, the generated organic acid will corrode the metal components, destroy the structure of the grease, reduce its dropping point, increase the viscosity of the base oil and reduce its fluidity when using the grease. A large number of tests have shown that the higher the temperature, the more obvious the decline in grease life. For example, when the temperature is 90 to 100 degrees, the service life of the grease will be reduced by about half for every 19 degrees of temperature increase, and when the temperature is 10 to 150 degrees, the service life of the grease will be reduced for every 15 degrees of temperature increase. will be reduced by half.
  4. In addition, the moisture, dust and harmful gases in the environment where the grease is used are also important factors for the deterioration of its performance. For example, if the grease is mixed with wear particles such as copper, iron, lead, bronze, etc., it will catalyze the oxidation of the grease.
  5. In short, there are many reasons for the failure of lubricating grease, sometimes it is caused by one reason, but more is the result of the interaction of multiple factors, or one reason is the breakthrough, and other reasons work together.
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