Causes Of Excessively High Temperature In Imported Bearings And Necessary Preventive Measures

The temperature of imported bearings can generally be estimated from the temperature outside the bearing housing. However, directly measuring the outer ring temperature of the imported bearing using an oil hole is even more suitable. Typically, the temperature of an imported bearing rises slowly as the bearing starts operating, reaching a stable state after 1-2 hours. The normal bearing temperature varies depending on the machine's heat capacity, heat dissipation, speed, and load. Improper lubrication or installation can cause a rapid rise in bearing temperature, resulting in abnormally high temperatures. In such cases, operation must be stopped and necessary preventative measures taken.

Using a thermal sensor allows for continuous monitoring of the bearing's operating temperature, enabling automatic alarms or shutdowns when the temperature exceeds specified values to prevent bearing burn-out accidents. High temperatures often indicate an abnormal bearing condition. High temperatures are also harmful to bearing lubricants. Sometimes, bearing overheating can be attributed to the lubricant. Prolonged operation of bearings exceeding 125°C will reduce bearing life. Causes of high bearing temperatures include: insufficient or excessive lubrication, impurities in the lubricant, excessive load, bearing ring damage, insufficient clearance, and high friction from oil seals, etc.

Therefore, continuous monitoring of the temperature of imported bearings is necessary, whether measuring the bearing itself or other critical components. Under constant operating conditions, any temperature change indicates a malfunction. Regular bearing temperature measurement can be achieved using a thermometer, such as a digital thermometer, which accurately measures bearing temperature and displays it in °C or Fahrenheit. Critical bearings, meaning those whose failure would cause equipment downtime, should be equipped with temperature sensors. Under normal circumstances, bearings will naturally warm up after lubrication or relubrication and this temperature will persist for one to two days.

Generally, imported bearings used at operating temperatures above 150°C are called high-temperature bearings. Because the hardness of chromium bearing steel decreases sharply and its dimensions become unstable above 150°C, the bearing cannot function properly. Therefore, for bearings operating between 150°C and 350°C, if the bearing rings and rolling elements are still made of ordinary high-carbon chromium bearing steel, special tempering treatment is necessary. Tempering should generally be performed at a temperature 50°C above the operating temperature. Bearing steel tempered according to the above requirements can be used normally at the operating temperature. However, because the hardness decreases after tempering, the bearing life is reduced.

Generally speaking, from a usage perspective, the following points should be noted:

1. Bearing clearance should be appropriate. Excessive clearance will cause impact, while insufficient clearance will result in poor lubrication and may lead to bearing failure.

2. The surface quality and geometry of imported bearings and journals should be strictly guaranteed.

3. Improve lubrication quality by controlling oil pressure, temperature, and flow rate, and enhance oil filtration.

4. Control the diesel engine's temperature. Operating in excessively cold or hot conditions is detrimental. In cold weather, the diesel engine should be preheated before starting, and the crankshaft should be manually rotated to allow oil to enter the friction surfaces.

5. Use fuel and lubricating oil that meet the specified requirements.