Basic knowledge of equipment “five senses” inspection and lubrication

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1. “Five Senses” inspection of equipment. What is “Five Senses inspection”? "The “five senses” refer to the senses of sight, hearing, smell, touch, and taste in humans. “Five-sense inspection” is a method in which, before, after, or during the operation of equipment, operators, inspectors, and those responsible for operation work together to use the five senses along with simple auxiliary tools such as listening sticks, inspection hammers, and thermometers. According to predetermined intervals and locations, they examine and assess various aspects of the equipment such as pressure, temperature, flow rate, leaks, lubrication conditions, abnormal noises, vibrations, cracks (breakages), wear and tear, and looseness, by relying on sight, hearing, smell, touch, and taste. The functions of human \"five senses\" and the method of \"sensory inspection\": What is perceived does not necessarily have to be understood; only what is understood can be perceived more deeply. Using the “five senses” for inspection is an activity that combines the functions of the human body’s five senses with existing knowledge and experience. The key is to select the appropriate part of the equipment, to gain more experience and accumulate knowledge and skills, so as to be able to detect subtle changes in its performance and characteristics compared to its normal operating state. 1. Visual perception: Statistics show that 60% of human actions begin with visual perception. Visual inspection has a very wide range of applications, and all types of inspections can begin with visual methods. For example, loose bearing seats can be detected from cracked coatings on the bearing seat, or misaligned alignment marks on the upper and lower bearing shells ； Observe changes in oil level and oil color to determine whether the lubrication system is operating properly ； Defects within electrical components can be observed through signs such as charring, discoloration, peeling, foreign objects, dust, and cracking. When using visual inspection methods, it is essential to conduct a thorough and careful observation. For example, when checking an electrical cabinet, one should not only look at the control panel but also open the cabinet doors to observe from various angles ； When checking the motor, it is necessary to look not only at the motor housing but also to open the end cover in order to further examine the rectification condition and spark level, etc. 2. Hearing: Humans are quite sensitive to sound wave stimuli, and the hearing method is primarily used to distinguish between abnormal sounds and normal sounds. Mechanical impacts, bearing damage, eccentricity, as well as rapid acceleration and deceleration of high-speed rotating machinery – all of these vibration sources can cause various components to loosen, resulting in abnormal impact sounds or irregular noises. Relays, contactors, motors, and transformers all have their own characteristic normal sounds; once familiar with these normal sounds, it becomes easier to detect abnormalities by comparison. Additionally, some stationary components, such as circuit boards and connectors, do not make any noise normally; however, if a \"cracking\" sound is heard, it is worth paying attention, as this is often caused by poor connections, loose screws or connectors, or abnormal conditions such as excessive current. Upon hearing an abnormal sound, it is necessary to strengthen the connection with other senses, or use tools such as listening sticks to identify the location of the anomaly. 3. Sniffing with the nose: The sense of smell plays an important role in the \"five senses inspection\" method; the detection of unusual odors through sniffing indicates that there is definitely something wrong with the equipment. The olfactory method is primarily used to detect abnormal odors caused by burning, etc. Since common electrical equipment typically has no peculiar odor, any unusual smell can be easily detected. This usually indicates either inter-turn short circuits in relays or motor windings, or insulation degradation and subsequent burning. Since fires can easily occur as a result of these situations, it is necessary to quickly identify abnormal points and shut down the system if required. 4. Touch: Touch is closely related to vision and hearing. Touching is used primarily to check temperature, vibration, and contamination. Excessively high temperatures not only accelerate insulation degradation but also shorten its lifespan. It can also easily cause accidents such as electric shock and burns, and its impact on the performance of electronic circuits is particularly significant. 5. Tasting: When using the \"five senses\" for inspection, tasting is generally not employed. Even in special situations where it is necessary to determine whether something is acidic or alkaline, it should be used cautiously, ensuring that it has no adverse effects on the body. "Basic conditions for the five-sense inspection: 1. Understand the equipment: Be familiar with the equipment that is to be inspected, know the production process, and be able to distinguish between normal and abnormal conditions of the equipment; develop the basic skills needed to detect abnormalities in the equipment through intuitive observation. 2. Familiarity with drawings: The ability to identify the cause of equipment abnormalities with the help of drawings, thereby aiding in judgment. 3. Correct judgment: Based on the equipment’s performance, operating instructions, and design data, correctly assess the load condition. 4. Master various standards: Be proficient in inspection standards, lubrication standards, etc. By comparing observations with these standards, one can accurately identify any abnormal signs. 5. Distinguishing key equipment: Master the evaluation forms for key equipment, and understand these devices as well as their critical components, so as to make the focus of inspection using the “five senses” clearer. 6. There should be standard operating values: various operational standards for the process, such as temperature, pressure, flow rate, pressure loss, speed, etc., which need to be clear and specific. 7. Continuously accumulate and enrich practical experience: Gain more experience and think more, so as to be able to detect abnormalities in equipment promptly. "Characteristics of the inspection standards for the five senses check: In the inspection standards that employ the \"five senses check\", most of them are qualitative standards; the results of such inspections are usually expressed as \"yes (good) or no\", \"present or absent\", etc. For example: Bolts should not be loose ； The bearing should have no abnormal vibration ； Good ventilation is required ； The high-voltage cabinet should be free of abnormal noises and odors ； The oil level should be within the specified range, etc.; these are all signs of normal equipment operation. When abnormalities are detected using the \"five senses\" method, since these senses cannot provide quantitative data such as the pitch of abnormal sounds or the intensity of vibrations, instruments must be used for quantitative testing and data analysis in order to accurately determine the degree of equipment degradation and its trends. "Examples of skills for \"sensory inspection\": 1. Method for checking loose bolts – Visual inspection: After installation or maintenance is completed, paint or a marker pen is used to draw a line between the bolt and the nut (between the screw head and the base). By observing changes in the position of these two elements over time, it is possible to determine whether the bolts are loose. Knocking method: Use an inspection hammer with a mass roughly equivalent to that of the nut, and hold it by the handle to strike the side surface of the nut or the head of the bolt. If it is tightened, a clear \"ding\" sound is produced, and the hand also vibrates. If it is loose, it emits a muffled sound, and no vibration can be felt by hand. When the equipment experiences low-frequency vibration, the first thing to do is to tighten the bolts. When monitoring equipment vibration, if the acceleration remains unchanged while the velocity increases, and it is not possible to stop the equipment immediately, one should first check and tighten the bolts before proceeding with further observation and diagnosis. 2. Simple methods for checking temperature: The hand-touch method: By touching or bringing the hand close to the heat-generating element, and determining the duration for which the hand can tolerate the heat, one can roughly estimate the temperature of the object. Measure the temperature using a fixed or simple thermometer, or an infrared temperature testing device. Method of determining temperature by touch: Inspection method: Use the index finger, middle finger, and ring finger of the right hand together; gently touch the surface to be measured with the middle part of the back of these fingers using a light pressing motion. Only when it is confirmed that no damage will be caused to the skin can the pulp of the fingers be used to determine the temperature. The temperature of the component being tested is around 0 degrees; it feels icy to the touch, and prolonged continuous contact can cause a piercing pain ； When the temperature of the component being tested is around 10 degrees, it feels cool to the touch, but it is generally tolerable ； When the temperature of the component being tested is around 20 degrees, it feels slightly cool to the touch; as the contact time increases, it gradually becomes warmer to the touch ； When the temperature of the component being tested is around 30 degrees, it feels slightly warm to the touch, which is comfortable ； When the temperature of the component being tested is around 40 degrees, it’s similar to touching a patient with a high fever ； When the temperature of the component being tested is around 50 degrees, it feels quite hot to the touch, and prolonged contact may cause sweating ； When the temperature of the component being tested is around 60 degrees, it feels very hot to the touch, but it can generally be tolerated for about 10 seconds ； When the temperature of the component being tested is around 70 degrees, the finger’s tolerance lasts only about 3 seconds; a burning sensation occurs, and the area in contact quickly turns red ； When the temperature of the component being tested is above 80 degrees, only brief contact is possible, and the pain intensifies (a burning sensation). If contact lasts too long, burns can occur. Image 2: Key points for equipment lubrication and maintenance. Mechanical devices’ friction pairs require the use of lubricants (greases) in order to reduce the friction coefficient between them, minimize wear on the machinery, and extend the device’s lifespan. SKF’s studies on bearing life show that the lubrication condition of bearings can result in a difference in their lifespan of up to 500 times, highlighting the importance of lubrication in extending the life of mechanical equipment. Routine inspection of lubricating oil: This involves visual inspection of the lubricating oil or performance testing of the lubrication system, to check whether its physical and chemical properties are within normal ranges. To some extent, this can help predict the likelihood of mechanical failures. Therefore, regular \"lubricant inspection\" is very important for the maintenance of mechanical equipment. The main contents are as follows: Key points for the daily maintenance of light oil lubrication systems. Point 1: Regularly check the physical and chemical properties of the lubricating oil. The aging and contamination of the lubricating oil are reflected in its appearance; through visual inspection: (1) Transparency: Take a sample of the lubricating oil into a test tube – if it is “turbid,” it indicates the presence of water; it should be a “transparent” liquid. If there are precipitates at the bottom of the test tube after sampling, filtration or replacement must be carried out immediately ； ⑵ Color change: Lubricating oil will definitely change color as a result of oxidation during use, and this change varies depending on the grade of the lubricating oil. Point 2: When replacing lubricating oil, it is necessary to check its cleanliness. Point 3: Keep detailed records of the amount of lubricant added. For fully submerged lubrication systems, a decrease in lubricant level is considered normal, while in circulating lubrication systems, such a decrease is considered abnormal, indicating that there is a leak somewhere; carefully investigate and record the cause of the decrease. Point 4: Strictly control the type of lubricating oil. The selection of lubricants can be based on those recommended by the machinery suppliers; however, when there are many devices and the manufacturer’s recommended oils still have to be used, the variety of oils increases, which not only makes management difficult but also poses a risk of supply errors. To this end, the quality and viscosity grades of lubricants are compared, and similar types of oils are grouped together to minimize the number of oil varieties. Point 5: The amount added to the lubricated areas should be appropriate; the level of the lubricating oil is determined based on the lubrication method to ensure it is at the right level. If too much lubricant is added, the oil is stirred excessively, causing bubbles to form, which reduces the effectiveness of the lubricant and leads to its premature aging. Point 6: The lifespan of lubricating oil is closely related to temperature, so the temperature of the lubricating oil must be strictly controlled. Generally, above 60°C, for every 10°C increase, the oxidation rate doubles, and the lifespan of the lubricant is reduced by half. To extend the lifespan of the lubricant, it is necessary to control the rise in oil temperature. Point 7: Avoid mixing different lubricants together, as this can cause chemical reactions between the additives in the lubricants, leading to their precipitation and separation, which in turn results in poor lubrication of the friction pairs in mechanical equipment. In this case, the lubrication system must be cleaned before it can be used. Point 8: Never overlook any minor oil leaks, as even the tiniest leaks can result in a considerable amount of oil loss over months and years. The table below calculates the leakage amount due to minor leaks per day, per month, and per year (unit: liters). Image: Key point 9 of the calculation method for minor leaks of light oil – One should not choose lubricant solely based on its viscosity; for different lubricants, even if their viscosities are the same, their properties can change, turning them into completely different types of lubricants. Point 10: Avoid choosing the wrong viscosity for bearing oil; if the viscosity is too high, it often leads to an increase in bearing temperature, resulting in vibration, humming noises, and bearing wear. It is prohibited to change the lubricant grade arbitrarily. Lubricants should be selected based on their purpose, operating conditions, and usage methods; if the wrong type of lubricant is chosen, it will fail to perform its lubricating function properly, thereby causing malfunctions in mechanical equipment. Key points for the daily maintenance of grease lubrication systems: Point 1 – The choice between using grease for lubrication or liquid oil depends on the amount of heat generated by the bearings; therefore, the appropriate type of lubricant should be selected. Grease does not have a cooling effect; in practice, there are many examples of switching from grease lubrication to oil lubrication, such as oil mist lubrication in continuous casting machines. Point 2: Choose the correct penetration grade for the grease. Point 3: When the bearing overheats, you can try using grease with a higher viscosity. Point 4: Choose the fat addition cycle and amount correctly. Point 5: Do not remove the upper cover when filling grease into the grease pump tank. Even with clean grease, if filling is done by removing the lid, impurities from the air will mix in along with it, and at the same time air will enter the grease container and be sent into the lubrication pipes. Point 6: After adding fat, verification is required; if the acceleration is lower than the previous normal value but remains unchanged, it is considered normal ； If the acceleration value increases, it may indicate that the bearing is damaged and repair must be carried out as soon as possible. Point 7: Do not neglect the inspection of grease pipelines. Grease pipelines are prone to issues such as detachment, bending, crushing, blockages, and breaks, which can lead to serious equipment failures; therefore, it is necessary to strengthen the inspection of these pipelines. Point 8: Do not blindly trust automatic grease pumps. Point 9: Before manually applying grease to the bearings, it is necessary to open the oil drainage hole. Motor bearings usually have a grease filling port and an oil drainage port; the latter is located below the bearing area, which is why it often goes unnoticed. If grease is applied without opening the oil drainage hole, grease will accumulate in the bearing area, making it difficult for the heat generated by the motor coils to be dissipated. This can ultimately lead to insulation problems and damage to the motor. Prohibitions regarding the daily maintenance of grease lubrication systems: Point 1 – Brushes are prohibited when applying grease. When applying grease to bearings or gears, using brushes will result in the inclusion of hair fibers; therefore, tools specifically designed for applying grease should be used. Point 2: Mixing two types of greases is prohibited. If two types of greases are mixed, the performance of the grease usually declines. Under normal circumstances, mixing lubricants of different types can lead to unexpected and severe consequences. Point three: Pollution of lubricant is prohibited. Lubricant is to machinery what drinking water is to us. Introducing contaminated grease can lead to equipment failures, and troubleshooting such issues becomes rather difficult. ①Requirements to be followed for grease application: ② Verify the lubricating oil ； ③The oil feeding port should be cleaned before and after the lipid feeding operation ； ④Use clean, dedicated tools ； ⑤Do not leave the grease container lid open. Point 4: It is prohibited to apply grease using a grease pump or grease nozzle when they are contaminated. Point 5: It is prohibited to use dirty gloves or tools for operations. Using dirty gloves or tools to fill a grease gun with grease can lead to the inclusion of debris or fibers, which may then end up in the friction surfaces of mechanical equipment and cause premature damage. Point 6: Overfilling with lubricant is prohibited. Lubricant does not have any cooling effect; excessive amounts of it prevent the heat generated during equipment operation from dissipating, which can lead to the lubricant burning and clumping together, thereby causing equipment failures. Point 7: It is prohibited to apply oil when the equipment is stopped. Applying grease to a stopped device can lead to an excessive amount of grease, which in turn causes the bearing temperature to rise when the equipment starts operating again. Point 8: It is prohibited to expose grease pipelines to high temperatures. When grease is used in high-temperature environments, the antioxidants are rapidly depleted, and the base oil oxidizes quickly as well, resulting in poor lubrication. When applying grease remotely, either automatically or manually, the piping route should be kept away from high-temperature areas, or insulation measures should be taken. Point 9: Lubricant feeding is prohibited after all the lubricant pipeline connections are completed. After the lubricant pipelines are connected, the pipelines on the oil supply side should be properly connected and those on the oil reception side removed before starting the lubricant feeding process. After filling the pipe with grease, before connecting it to the oil-receiving side pipe, scrape off about 2 cm of grease from the end of the pipe; grease can then be applied after connecting it to the oil nozzle on the oil-receiving side. Point 10: It is prohibited to connect empty pipes to the grease piping. During the maintenance of mechanical equipment, pipes sometimes get crushed or bent, and in such cases it is necessary to reconfigure the piping and fill it with grease before making connections. If empty pipes are connected, it is difficult to supply grease at first, and it may take several days for the automatic grease supply system to function properly. Point 11: It is prohibited to use lubricant pipes that are too long. Excessively long pipes increase the impedance of the piping, making it difficult for the lubricant to reach its destination; they also increase the risk of the pipes breaking, and the lubricant inside the pipes is more likely to age. Key points for the daily maintenance of level gauges: Point 1 – Do not neglect to verify the proper operation of the level gauge; floating level gauges may sometimes malfunction due to contamination in the areas where the floating guides are located ； Point 2: Do not rely too much on level gauges ； Point 3: Clean the sludge in the level gauge in a timely manner. It is prohibited to determine the cleanliness of the lubricating oil based on its visual appearance in the level gauge. Key points for the daily maintenance of oil purification units (filtering devices): Point 1 – Do not forget to clean the filter cartridges ； Point 2: Don’t rely too much on filters ； Point 3: The hoses for the inlet and outlet of the oil purifier should not be placed too close to each other. The inlet should be installed as low as possible in the tank, while the outlet should be located at the upper part of the tank; the outlet and inlet should be kept as far apart as possible. If it is too close, it is difficult to draw in the oil from farther away, resulting in a longer time required for oil purification ； Point 4: Do not discard the filter element that has been replaced due to clogging immediately. The impurities adhering to the outside of the filter element allow one to assess the operating condition of the mechanical equipment, enabling early prevention of problems. Key points prohibiting routine maintenance of oil purification units (filtering devices) Point 1: It is prohibited to ignore clogs in the filters ； Point 2: It is prohibited to neglect the magnetic filter in the lubrication system’s oil tank. A magnetic filter uses permanent magnets to attract solid particles that come within a certain distance, thereby maintaining the purity of the oil. Magnetic impurities in the oil tank are absorbed in large quantities and accumulate in a foamy state. If left unaddressed, when the lubrication system starts up, the oil in the tank becomes turbulent, and the solid particles of impurities attached to the magnets will return to the lubrication circuit, causing a fault that leads to shutdown ； Point 3: It is prohibited to clean the filter element in dusty areas. Prohibitions for daily bearing lubrication maintenance: Point 1 – Do not allow the bearings to come into contact with contaminants ； Point 2: Do not assemble new bearings while they are still in their packaging ； Point three: When applying grease to a bearing housing equipped with an oil seal, it is necessary to remove the drain plug. If there is no drain port, a screwdriver should be used to create a gap in the oil seal before applying the grease; otherwise, the pressure exerted during greasing may cause the oil seal to fall out of the mounting groove in the bearing housing ； Point 4: Do not install the bearing bush oiling hole on the compressed side. Prohibitions in the daily maintenance of bearing lubrication: Point 1 – Heating oil-containing bearings is prohibited, as the grease inside them can be lost due to high temperatures, resulting in a decline in performance ； Point 2: Cleaning oil-bearing bearings is prohibited. Even if oil-bearing bearings are contaminated, cleaning oil should not be used. Once cleaning oil is used, the oil contained in it is washed away, resulting in insufficient lubrication and causing wear. Prohibitions regarding the daily maintenance of chain and wire rope lubrication: Point 1 – It is prohibited to lubricate the chain in an environment with dust ； Point 2: Refueling is prohibited on the tension side of the chain ； Point 3: It is prohibited to wipe off the oil from the chain. The structure of a roller chain consists of sleeves installed on the outside of its pins, with rollers placed on the outside of those sleeves. The wear in these 3 parts can cause the chain to sway. At this location, if grease is applied from the outside, it is difficult for the lubricant to penetrate inward, resulting in only superficial lubrication. The best lubricant should be one that is penetrative. The elongation caused by chain wear is due to the loss of oil between the sleeve and the pin. Lubrication with grease must be avoided; instead, lubrication with light oil should be used. At the same time, the oil viscosity should be VG100~150 for the best result. Image 3: Daily Work Instructions. Purpose: Work instructions serve as a benchmark for supervisors to provide proper guidance on standard operations to workers. Work instructions are prepared based on part capability sheets and work order sheets. It specifies, in accordance with the order of tasks, the task contents for each individual as well as the key points regarding safety and quality for the production volume required by each production line. Therefore, a chart is used here to represent the machine configuration for a particular task, showing the cycle time, task sequence, and standard inventory levels. In addition, it indicates where and by what method quality inspections are carried out. If the operator follows the instructions, the task can definitely be completed efficiently, quickly, and safely.