Checking the condition of the running machine and preparing a thorough inspection plan has become more and more serious. The bearing is the focus of attention because it is the most important rotating part of all machines. Condition monitoring is an important part of preventive maintenance. Early detection of bearing damage prevented equipment downtime during unplanned maintenance due to bearing damage. However, not all of them are equipped with this advanced instrument. In this case, the operator or maintenance engineer of the machine must be highly alert to the "fault signal" of the bearing, such as noise, temperature and vibration. “Listening,†“touching,†and “observing†are three important factors. The following comments can be used as a reference.
First, touch
High temperatures often indicate that the bearing is in an abnormal condition. High temperatures are also detrimental to the lubricant in the bearings. Sometimes the bearing overheating can be attributed to the lubricant of the bearing. If the bearing runs for a long time at a temperature exceeding 125 degrees Celsius, the bearing life will be reduced. The causes of the high temperature bearing include: insufficient lubrication or excessive lubrication, impurities in the lubricant, and excessive load. , bearing damage, insufficient clearance, and high temperature friction caused by the oil seal. Therefore, it is necessary to continuously monitor the bearing temperature, whether it is measuring the bearing itself or other important parts. If the operating conditions are not changed, any temperature change may indicate that a fault has occurred.
Regular measurement of the bearing temperature can be done with the aid of a thermometer to accurately measure the bearing temperature and display it in degrees Celsius. The importance of the bearing means that when it is damaged, it will cause the equipment to stop. Therefore, it is better to install a temperature detector for this type of bearing. Under normal conditions, the bearing will naturally rise in temperature after lubrication or relubrication and last for one or two days.
Second, observe
If the bearing is well lubricated and properly blocks debris and moisture, it means that the oil seal should be free of wear. However, it is best to visually inspect the bearing and periodically check the oil seal when opening the bearing housing to check the condition of the oil seal near the bearing. To ensure that they are sufficient to prevent hot liquid or corrosive liquids or gases from penetrating into the bearing along the axis. The protective ring and the labyrinth oil seal should be greased to ensure maximum protection. If the oil seal has worn out, it should be replaced as soon as possible. In addition to preventing the magazine from entering the bearing, the function of the oil seal is to keep the lubricant in the bearing housing. If there is oil leakage in the oil seal, immediately check whether the oil seal has worn out or the oil plug is loose. The phenomenon of oil leakage may also be caused by the loose joint surface of the bearing housing or the agitation and oil leakage caused by excessive lubricant addition. Check the automatic lubrication system to ensure the correct amount of addition, and check whether the lubricant is discolored or blackened. If this is the case, it usually means that the lubricant contains a magazine.
Third, listen
Using auditory to identify irregular movements is a very common approach. For example, an electronic stethoscope is used to check for abnormal noise of a part by an experienced operator. If the bearing is in good operating condition, it will make a low humming sound. If a sharp voice is heard, the voice and other irregular sounds usually indicate that the bearing is in poor operating condition. Sharp squeaking noise may be caused by improper lubrication. Improper bearing clearance can also cause metallic sound. The indentations on the outer ring of the bearing cause vibration and result in a smooth and crisp sound. If the knocking flaw caused by the installation also produces noise, the noise will vary with the speed of the bearing. If there is intermittent noise, the rolling parts may be damaged. This sound occurs when the damaged surface is crushed, and if there is a pollutant in the bearing, it will often cause a click. Severe bearing damage can result in irregular and large noise.
Bearing damage can be detected by hearing, but usually the bearing must be replaced immediately. Therefore, a better method, for example, uses an electronic condition monitoring instrument to pre-diagnose the operation of the bearing.
Compared to the old method (using a wooden stick or screwdriver to the bearing housing and the other end to the ear), advanced conditions can be used to accurately estimate the bearing condition.
Fourth, grease lubrication
Relubrication of the bearings is best carried out during planned equipment downtime and is regularly replenished. At the same time, the old grease is cleared or the old grease is removed through the drain plug. Wipe the nozzle clean before adding new oil. If the bearing housing does not have a grease fitting, open the bearing housing cover or end cap to remove the old grease and then replenish the same fresh grease.
Five, oil lubrication
When inspecting the oil level of the bearing, make sure that the oil type used is correct and that the vent hole of the oil level is blocked.
A small amount of oil was taken as a sample and compared to fresh oil. If the sample appears to be cloudy, it may be the result of mixing with water and should be replaced. If the sample is darkened or thickened, it may indicate that the oil begins to carbonize. Replace all old oil and, if possible, use fresh oil to flush the bearings. When changing the oil, make sure that the oil type you are replacing must be the same and replenish it to the required oil level.
If there is a more reliable way to determine the oil condition, then the sample is analyzed. If the oil is contaminated, the oil seal should be replaced or the filter should be considered.
Use an oil bath type lubrication system. If the operating temperature does not exceed 50-60 degrees Celsius and the oil is not contaminated, replace the oil once a year. If the operating temperature is 100 degrees Celsius, replace the oil 4 times a year. If the operating temperature is 120 degrees Celsius, replace the oil every month. If the operating temperature is 130 degrees Celsius, replace the oil every week.
Proper installation and maintenance is an important factor in the longest service life of the bearing. At the same time, attention must be paid to the cleanliness of the bearings, the correctness of the choice of bearings and the selection of appropriate installation and maintenance tools. Bearings must be protected from contaminants and moisture and must be properly installed and lubricated. The design of the bearing arrangement, the condition of the oil seal, the type of lubricant and the lubrication cycle, and even the special maintenance play an important role.
Concerned about surprises
Label: Bearing life Bearing damage Bearing clearance Oil level Operating conditions
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