Let’s all discuss on-site maintenance techniques together and summarize them for a prize

Discuss together, improve together. This post was last edited by zcs002 on 2007-12-7 17:08.]

Support original content~ Great suggestion. This post was last edited by zcs002 on 2007-12-7 17:08.]

1. Apply what you’ve learned in practice, and make use of various tips and tricks. 2. Communicate more with experienced professionals to learn their best practices

Heating the bearings on the steam pipeline is probably not a good idea. When heating bearings, it is essential to ensure 1. uniform heating. 2. The temperature should be kept within the allowable range. How to ensure heating in steam pipelines? I think that to improve maintenance efficiency, it would be better to make proper preparations and take full account of the actual conditions on site.

When assembling bearings, the tolerances of the shaft, as well as the bearing’s model and precision grade, must be taken into consideration. For higher grades, oil heating is better.

I agree with the technical view from the 5th floor: bearings are precision components, so their heating must be done in a controlled manner, using specialized tools or oils for heating

I agree with the original poster’s view, but I think there must be better ways; let’s all think about it together.

For heating bearings, my approach is as follows: 1. When working on site, a bearing electromagnetic heater can be used. 2. An electric heating box can be used when the equipment is returned to the team for maintenance. 3. Large bearings are generally boiled in oil.

Simple diagnosis of rolling bearings 1. Monitoring rolling bearings using the stethoscope method. A common tool for monitoring the operating condition of rolling bearings using this method is a screwdriver with a wooden handle; a hard plastic tube with an outer diameter of around φ20 mm can also be used. Relatively speaking, using an electronic stethoscope for monitoring is more conducive to improving the reliability of monitoring. 1) Acoustic characteristics of rolling bearings in normal operating condition: When rolling bearings are operating normally, they run smoothly and quietly, without any pauses; the sound produced is harmonious and free of noise. A uniform and continuous \"whooshing\" sound, or a lower-pitched \"humming\" sound, can be heard. The noise level is not high. 2) Bearing failures indicated by abnormal noises (1) A uniform and continuous \"hissing\" sound emitted by the bearing; this sound is produced by the rotation of the rolling elements within the bearing, and it includes irregular metallic vibration noises that are independent of the rotational speed. It is generally manifested by insufficient grease in the bearing, which should be replenished. If the equipment is shut down for an extended period of time, especially in low-temperature conditions during winter, the bearings may sometimes emit a hissing or rustling sound, which is related to a reduction in the radial clearance of the bearings as well as a decrease in the penetration value of the lubricating grease. The bearing clearance should be adjusted appropriately, and new lubricant with a higher penetration value should be used. (2) The bearing emits a uniform, periodic \"hooing\" sound accompanied by a continuous \"whooshing\" noise; this sound is caused by scratches, grooves, and rust spots on the rolling elements as well as on the raceways of the inner and outer rings. The period of the sound is proportional to the rotational speed of the bearing. The bearing should be replaced. (3) The bearing emits a discontinuous \"clunking\" sound; this sound is caused by a rupture in the cage or the inner and outer rings. The machine must be stopped immediately to replace the bearing. (4) The bearing emits an irregular and uneven \"clattering\" sound; this sound is caused by the presence of impurities such as iron shavings and sand particles inside the bearing. The sound intensity is low and has no relation to the rotational speed. The bearing should be cleaned, re-lubricated, or have its oil changed. (5) The bearing emits a continuous and irregular \"rustling\" sound; this sound is usually related to either an overly loose fit between the inner ring of the bearing and the shaft, or an overly loose fit between the outer ring and the bearing hole. When the sound intensity is high, the fit of the bearings should be checked, and any issues found should be repaired promptly. (6) The bearing emits a continuous, harsh whistling sound. This sound is caused by poor lubrication of the bearing or a lack of oil, which leads to friction; it can also be resulting from excessive local contact between the rolling elements, such as misalignment of the inner and outer raceways, or too tight fit between the inner and outer races of the bearing. Bearings should be inspected promptly to identify problems and take appropriate action. 3) Requirements for monitoring using an electronic stethoscope: (1) During the monitoring process, it is advisable to use monitoring points of the same type or those with similar operating conditions in order to compare sounds; any abnormalities detected should be considered as defects, and thorough inspection is necessary. For a single device, in order to overcome the issue of lack of comparability, audio recordings of the sound under normal operating conditions can be used as a reference for future monitoring. (2) The location of the monitoring point must be selected properly; the vibration direction to be measured should be consistent with the sensitive direction of the sensor, so that the measurement is taken in the direction of maximum vibration intensity. The sensor should be at a right angle to the surface being measured, with the error required to be within 10°. (3) The surface to be measured must be clean and flat, free of rust or paint, and any recessed areas should be polished to make it smooth and even. (4) The measuring force applied to the probe should be around 10–20 N. 2. Monitoring of rolling bearings using the magnetic plug method 1) Requirements for monitoring rolling bearings with magnetic plugs Magnetic plugs are only suitable for monitoring critical main bearings that use lubricating oil and have a dedicated pipeline for oil return. The magnetic plug should be installed as close as possible to the main bearing being monitored, along the main return path for oil, with no filters, hydraulic pumps, or other hydraulic components in the way. 2) Morphological characteristics of wear particles under normal conditions: During the running-in period or normal operation of rolling bearings, the size of the wear particle fragments generated is 0.01–0.015 mm, and they contain some metal powder as well. During the running-in period, the new bearings produce more wear particle fragments than during normal operation. After entering the normal operating phase, the amount of abrasive fragments and metal powder decreases significantly. Under a microscope, the abrasive particles appear as thin and short shapes with irregular cross-sections. 3) Shape characteristics of abrasive particles caused by faulty wear: The main failure modes of rolling bearings are fatigue pitting and rolling fatigue. The size of the abrasive particle fragments that break off is generally 0.025–0.05 mm; sometimes there are also fragments of larger size, along with some metal powder. The abrasive fragments of ball bearings are usually in the shape of roughly circular rose petal-like structures separated radially, while those of raceways are roughly circular with a fractured surface. The abrasive fragments of roller bearings are typically curled rectangular shapes with a length that is 2-3 times their width, whereas those of raceways are generally irregular rectangular shapes. 3. Monitoring of rolling bearings using measurement methods: By measuring the temperature rise during the operation of the bearings, it is generally difficult to detect localized damage such as fatigue spalling, cracks, or indentations in the bearings; especially in the early stages of damage, it is almost impossible to identify any issues. When a bearing experiences an increase in temperature after long-term normal operation, the problem it indicates is usually quite serious, and it will develop rapidly, leading to bearing failure. At this time, intermittent monitoring often leads to missed detections. If the bearing temperature exceeds 70-80°C during monitoring, the machine should be stopped immediately for inspection. For newly installed or readjusted rolling bearings, by using temperature measurement methods to monitor their temperature rise over a specified period of time, it is possible to assess the quality of their installation and adjustment; especially when the clearance is too tight, excessive temperature rise occurs. Adjusting in a timely manner when problems are detected helps to extend the service life of rolling bearings. Everyone exchanges knowledge together.

Common simple methods for diagnosing equipment failures – I’m not sure if they will be useful to everyone. The common simple methods for monitoring equipment condition include auscultation, tactile inspection, and observation. 1. Auscultation: When the equipment is operating properly, the sounds produced always have a certain rhythm and pattern. By becoming familiar with and mastering these normal melodies and rhythms, one can use their auditory senses to detect any abnormal noises such as heavy, noisy, strange, or chaotic sounds coming from the equipment, and thus identify potential issues like looseness, collisions, or imbalance within it. By hitting the part with a hammer and listening for any cracking noises, it is possible to determine whether cracks have formed. An electronic stethoscope is a vibration acceleration sensor. It converts the vibration conditions of the equipment into electrical signals and amplifies them; workers use headphones to listen to the vibrations of the operating equipment, thereby enabling qualitative measurement of those sounds. By measuring the signals at the same measurement point at different times, under the same rotational speed and under the same operating conditions, and comparing them, it is possible to determine whether there is a fault in the equipment. When crisp and high-pitched noises are heard from the headphones, it indicates a high vibration frequency; usually, this is caused by local defects or tiny cracks in components that are relatively small in size but have relatively high strength. When the headphones produce a muffled, low-frequency noise, it indicates that the vibration frequency is low; generally, this is due to large cracks or defects in components that are relatively large in size and have relatively low strength. When the noise coming from the headphones increases compared to normal, it indicates that a fault is developing; the louder the sound, the more severe the fault. When the noise coming from the headphones appears in a random and intermittent manner, it indicates that a component or part is loose. 2. Touch sensing method: The tactile sense of the human hand can be used to monitor changes in the equipment’s temperature, vibration, and clearance. The nerve fibers in the hands are sensitive to temperature, allowing them to detect temperatures down to 80°C with relative accuracy. When the temperature of the component is around 0°C, it feels icy to the touch; prolonged contact can cause a piercing pain. At around 10°C, it feels cool to the touch, but it is generally tolerable. At around 20°C, it feels slightly cool to the touch; as contact time increases, it gradually becomes warmer. At around 30°C, it feels slightly warm to the touch, providing a comfortable sensation. At around 40°C, it feels warm to the touch, with a slight burning sensation. At around 50°C, it feels quite hot to the touch; if one presses with the palm for an extended period, sweating will occur. At around 60°C, it feels very hot to the touch, but it is generally tolerable for up to 10 seconds. At around 70°C, it feels scorching hot to the touch; one can generally only tolerate it for about 3 seconds, and the area touched by the hand turns red very quickly. When touching, touch it first and then feel it more carefully to estimate the temperature rise of the component. By shaking the component by hand, it is possible to sense the gap size of 0.1mm–0.3mm. By touching the components with your hand, you can sense changes in the intensity of vibration and whether shocks are generated, as well as the movement of the sliding plate. Using a thermometer equipped with a surface thermocouple probe to measure the surface temperature of components such as rolling bearings, sliding bearings, spindle boxes, and motors offers the advantages of rapid identification of the location of thermal abnormalities, accurate data, and a convenient measurement process. 3. Observation method: The human eye can be used to check whether there is any looseness, cracks, or other damage in the components of the equipment ； It is possible to check whether the lubrication is proper, as well as to detect any signs of dry friction or leaks ； It is possible to examine the quantity, size, and characteristics of metal particles in the fuel tank sediment in order to assess the wear level of related components ； It is possible to monitor whether the device is moving properly and to detect any abnormal phenomena ； It is possible to view the various gauges installed on the device, which indicate its operating status, in order to monitor changes in the data. Product quality can be checked, and the device’s operating condition can be assessed by using measuring tools and by directly observing the surface condition. By conducting a comprehensive analysis of the various observations, it is possible to determine whether there is a fault in the equipment, identify the location of the fault, assess the severity of the fault, and determine its cause. A simple method for monitoring wear conditions by using instruments to observe the wear particles collected from the equipment’s lubricant is the magnetic plug method. Its principle involves inserting a magnetic plug into the lubricating oil to collect the iron particles generated by wear; by using a reading microscope or simply observing with the naked eye, the size, quantity, and shape of these particles are examined in order to determine the degree of wear on the surface of mechanical parts. The magnetic plug method can be used to observe the larger particle sizes that appear in the later stages of wear of mechanical parts. During inspection, if small abrasive particles are found in small quantities, it indicates that the equipment is operating properly ； If large abrasive particles are detected, it is necessary to pay close attention and closely monitor the operating condition of the equipment ； If large particles are detected repeatedly in a row, it is a sign that a failure is imminent; the machine should be stopped immediately for inspection to identify and resolve the issue. For auscultation, the tip of a screwdriver (or a metal rod) can be used to point at the area to be examined; hold the screwdriver with your hand and listen carefully. Doing this can filter out some noise. Temperature tactile judgment training: Using a single-node thermometer, measure the metal surface at temperatures of 50 degrees, 60 degrees, 70 degrees, and 80 degrees. For lower temperatures, timing can be used to determine how long the hand can remain in contact with the surface, and the temperature can be inferred based on this duration. When the high temperature is too hot to touch, a few drops of water can be sprayed to observe the evaporation process, and then these states should be remembered. It is used for diagnosing equipment, enabling more accurate judgments. If the score is low, I won’t post it, hehe! Support forum development and information sharing!

The views expressed upstairs are mostly based on what’s in books; in actual maintenance work, one needs to apply these principles flexibly and learn from front-line workers, adopting their strengths for one’s own use. In short, it’s about integrating theory with practice. There are three levels of learning: the lawful, the unlawful, and the neither-lawful-nor-unlawful. Follow the laws and regulations, act in accordance with rules and standards ； It’s illegal to question the norms and what’s written in books; it’s about understanding them theoretically and knowing why certain things are done that way. It’s not illegal; it involves bringing in new ideas by offering one’s own good, proven experiences and methods. This is just my personal opinion; please feel free to correct me.

1. Precautions for bearings during operation: Listening, checking the condition of the machine while it is in use, and having a thorough inspection plan in place have become increasingly important. Among these, bearings are of particular focus, as they are the important rotating components in all machines. Condition monitoring is an important part of preventive maintenance. Early detection of bearing damage can prevent unplanned equipment shutdowns caused by such damage. Bears that are used in critical machines or in harsh environments should be inspected more frequently, especially. Currently, there are a considerable number of systems and instruments available in the market for monitoring bearings, and most of these instruments are based on vibration measurement. However, not all machines are equipped with this advanced instrument. In such cases, the machine operator or maintenance engineer must be highly vigilant to fault signals of the bearings, such as noise, temperature, and vibration. Listening, touching, and observing are three important factors. The views provided below can serve as a reference for you. Listening – using hearing to detect irregular operations is a very common method. For example, using an electronic stethoscope to detect abnormal noises from a certain component is a method commonly employed by experienced operators. If the bearing is in good working condition, it will emit a low humming sound. If sharp hissing, squealing noises, and other irregular sounds are heard, it usually indicates that the bearing is not operating properly. A sharp squeaking noise may be caused by inadequate lubrication. Improper bearing clearance can also cause metallic noise. Grooves on the outer ring race of the bearing can cause vibration and result in a smooth, crisp sound. If there are dents caused by installation, they can also generate noise, and this noise varies depending on the speed at which the bearing rotates. If there is intermittent noise, it indicates that the rolling elements may be damaged. This sound occurs when the damaged surface is rolled over; dirt inside the bearing often causes a hissing noise. Severe bearing damage can produce irregular and loud noises. While bearing damage can indeed be detected by listening, by that point it is usually already necessary to replace the bearing immediately. Therefore, a better approach is to use instruments such as pulse monitors to diagnose the operating condition of bearings in advance. II. Precautions for bearings in operation: Touching and observation. Touching – High temperature often indicates that the bearing is in an abnormal condition. High temperatures are also harmful to the lubricant inside the bearings. Sometimes, bearing overheating can be attributed to the bearing’s lubricant. If the bearing operates at temperatures above 125°C (260°F) for an extended period, its lifespan will be reduced. The reasons for excessive bearing temperature include insufficient or excessive lubrication, impurities in the lubricant, excessive load, damaged bearings, insufficient clearance, and high friction caused by oil seals, among others. Therefore, it is necessary to continuously monitor the bearing temperature, whether by measuring the bearing itself or other important components. If the operating conditions remain unchanged, any change in temperature may indicate a fault has occurred. Bearings of critical importance mean that their failure can lead to the shutdown of equipment or installations; therefore, it is advisable to equip such bearings with temperature sensors. Under normal conditions, bearings experience a natural temperature rise immediately after lubrication or re-lubrication, and this rise persists for one or two days. Observation: If the bearing is properly lubricated and protected from debris and moisture, it indicates that there should be no friction in the oil seal. However, it is best to visually inspect the bearings when opening the bearing housing and to check the oil seals regularly. Check the condition of the oil seals near the bearings to ensure that they are sufficient to prevent hot liquids, corrosive liquids, or gases from seeping into the bearings along the shaft. The protective ring and labyrinth seal should be coated with grease to ensure maximum protection. If the oil seal is worn, it should be replaced as soon as possible. In addition to preventing contaminants from entering the bearing, another function of the oil seal is to retain the lubricant within the bearing housing. If oil leakage occurs from the oil seal, it is necessary to immediately check whether the seal is worn or damaged, or whether the oil plug is loose. Oil leakage may also be caused by loose joint surfaces in the bearing housing, as well as by stirring and oil leakage resulting from an excessive amount of lubricant. Check the automatic lubrication system to ensure that oil or grease flows properly into the bearings and that the correct amount is used; also check whether the lubricant has changed color or turned black, as such changes indicate that the lubricant contains impurities. III. Precautions for bearings in operation: Lubrication – Grease lubrication. It is best to re-lubricate the bearings while the equipment is shut down, and to top up the grease regularly. At the same time, remove the old grease or squeeze it out through the oil drain plug. The oil feed nozzle should be wiped clean before adding fresh oil. If the bearing housing does not have a grease filling port, the housing cover or end cap should be opened to remove the old grease, after which the same fresh grease should be added. Oil lubrication: A small amount of oil is taken as a sample and compared with fresh oil. If the sample appears cloudy, it may be due to mixing with water, and it should be replaced. If the sample appears darker in color or thicker, it may indicate that the oil has begun to carbonize; in such cases, all of the old oil should be replaced, and fresh oil should be used to clean the bearings if possible. When changing the engine oil, ensure that the same type of oil is used, and top it up to the required level. A more reliable way to determine the condition of the oil is to analyze a sample; if the oil is contaminated, the oil seal should be replaced or filters should be considered.

For a technical technician who performs on-site maintenance, looking, touching, and listening are basic work skills. As for whether there is a fixed method for on-site repairs, my years of experience tell me that having specific strategies is more effective; after all, how can you deal with equipment failures that you have never seen or encountered before if you don’t have any strategies? Relying on no strategies is too naive. Hehe! Technology deals with tangible things! ! Maintenance should follow a fixed procedure to ensure that work is carried out in an orderly manner and to avoid any improper operations.

1. Before performing maintenance on the equipment, it is essential to determine the cause of the malfunction and the exact location of the problem. We need to understand why we are carrying out maintenance on this equipment and what the purpose is Be targeted and purposeful ； 2. Before servicing the equipment, it is also necessary to carefully read the equipment’s maintenance and repair procedures. Understand the structure of the equipment, the disassembly methods and steps, the tools required, as well as the precautions to take. Fight a battle prepared for it.

The reasons for bearing overheating and the corresponding solutions are as follows: (1) The lapping of the bearing shells does not meet the requirements. The solution is to repair the bearing shells again or replace them. (2) The bearing clearance is too small. The solution is to readjust the bearing clearance or perform scraping. (3) Insufficient amount of lubricating oil and poor oil quality. The solution is to increase the oil volume or replace the lubricant. (4) Poor bearing assembly. The solution is to check the bearing assembly as required and eliminate any factors that do not meet the specifications. (5) Cooling water circuit breaker. The treatment method is inspection and repair. (6) Bearing wear or looseness. The solution is to repair the bearing or discard it. Wakamatsu Kyō, retighten the relevant bolts. (7) Pump shaft bent. The solution is to correct the pump shaft. (8) The oil slinger is deformed; it cannot rotate and thus cannot transfer oil. The solution is to replace the oil slinger. (9) Poor coupling alignment or too small axial clearance. The solution is to check the alignment and adjust the axial clearance.

Personally, I believe that theory is the foundation while experience helps to improve skills. For college graduates who are dedicated to maintenance work, learning humbly from experienced craftsmen is the basic way to improve themselves. By applying what they have learned in practice and working together as a team, they can do their job well

The skill in on-site maintenance lies in carrying out maintenance in a planned and focused manner. A plan should be developed for maintenance, taking into account the different characteristics of various devices. :) :)

It is very important to identify faults before equipment maintenance. Additionally, it is necessary to prepare the necessary spare parts and maintenance schedules. During maintenance, extra tasks often arise, as some hidden damages cannot be detected through experience; it is common to discover that certain components are severely worn only after the equipment has been disassembled. Therefore, preparing spare parts in advance is crucial. Moreover, established companies with long operating histories also maintain maintenance schedules for their equipment, which is very important as it helps to prepare for the need for spare parts.

On-site maintenance comes in different forms, including planned maintenance and emergency repairs. The tasks involved in maintenance are also varied, covering stationary equipment, operating equipment, electrical systems, instruments, etc.; therefore, specific actions must be taken depending on the circumstances.