Maintenance Engineering After Mid-Term PDF

After mid-term: Breakdown Trigger repairs and corrective actions An equipment breakdown should activate two actions: 1) Fast repair of malfunction equipment. 3) Modification/Redesign of malfunction 2) Development of a program to eliminate cause equipm...

After mid-term: Breakdown Trigger repairs and corrective actions An equipment breakdown should activate two actions: 1) Fast repair of malfunction equipment. 3) Modification/Redesign of malfunction 2) Development of a program to eliminate cause equipment. of the malfunction and need for such repairs in 4) Training of operators to improve machine care. the future. 5) More frequent predictive maintenance/inspection. Extent of repairs 1) Do just enough repairs to get equipment running again. 2) Repair the malfunction and replace some parts that are worn. 3) Replace the old equipment with new. Advantages of letting workers repair their own machines 1) Increase flexibility 2) Can make minor repairs faster 3) Can avoid minor repairs by cleaning, lubricating, adjusting, and servicing machines. 4) Operate machines more carefully. Reasons for PM programs 1) Reduce the frequency and severity of interpretations due to malfunctions. 2) Extend the useful life of equipment. 3) Reduce the total cost of maintenance by substituting PM costs for repair cost. 4) Provide a safe working environment. 5) Improve the product quality by keeping equipment in proper adjustment. PM data base requirements 1) Detailed records, or an ongoing history, must be maintained on each machine. a) Dates and frequency of breakdowns b) Descriptions of malfunctions c) Costs of repairs 2) Machine specifications/checklists for PM inspection 3) Computers generally can be kept in plastic pocket on a machine. Modern approaches to PM 1) PM at the source-workers have the fundamental responsibility for preventing machine breakdowns by conducting PM on their own machines 2) Workers listen for indications of potential equipment malfunction 3) Maintenance-related records maintained by workers. Decision analysis in PM Three decisions in particular 1) Determining the number of spare parts to carry 2) Determining how often to perform PM on group of machines 3) Planning and controlling a large-scale PM project. Determining the number of spare parts to carry for PM inspections Two types of parts demand arise from PM inspections 1) Parts that we routinely plan to replace at the time of each inspection (demand that is certain) 2) Parts, discovered during an inspection, in need of replacement (demand that is uncertain) Maintenance management and control Maintenance management 1) The management and control of maintenance activities are equally important to perform maintenance. 2) Maintenance management may be described as the function of providing policy guidance for maintenance activities, in addition to exercising technical and management control of maintenance programs. 3) Generally, as the size of the maintenance activity and group increases, the need for better management and control become essential. 4) In the past, the typical size of a maintenance group in a manufacturing establishment varied from 5 to 10% of the operating force. 5) Today, the proportional size of the maintenance efforts compared to the operating group has increased significantly, and this increase is expected to continues.  6) The prime factor behind this trend is the tendency to increase the mechanization and automation of many processes. 7) Consequently, this means lesser need for operators but greater requirements for maintenance personnel. 8) Maintaining the production capability of a organization is an important function of production and operation management. 9) Maintenance refers to upkeep and protection of: a) Plant b) Building c) Machinery d) Other fixed items Maintenance and maintenance management difference Maintenance: Function of production management that is concerned with day-by-day problems of keeping the physical plant in good operating conditions. Maintenance management: Concerned with planning, organizing and directing the resources in order to control the availability and performance of the industrial plants to some specified level. Categories of maintenance: There are two Categories of maintenance: 1) Maintaining buildings, parking lots, lawns and fences etc. 2) Maintaining equipment, machinery, material handling, transport vehicles, test instruments etc. Objectives of maintenance management: 1) Minimizing loss of production time 5) Prolonging the life of capital 2) Minimizing the repair time and repair cost 6) To keep all productive assets in good working 3) Minimizing the loss due to production condition stoppage 7) To maximize efficiency and economy 4) Efficient use of maintenance personnel and 8) Improving products quality and productivity equipment Impact of poor maintenance management: 1) Production capacity 2) Production cost 3) Product and service quality 4) Customer satisfaction Maintenance planning: 1) Know the process/ issues 5) Prepare list 2) Establishing priorities 6) Estimate 3) Investigate 7) Provide 4) Develop Maintenance department function and organization A maintenance department is expected to perform a wide range of functions including: 1) Planning and repairing equipment/ facilities to acceptable standards 2) Performing preventive maintenance; more specifically, developing and implementing a regularly schedules work program for the purpose of maintaining satisfactory equipment/facility operation as well as preventing major problems. 3) Preparing realistic budgets that details maintenance personal and material needs. 4) Managing inventory to ensure that parts/ materials necessary to conduct maintenance tasks are readily available. 5) Keeping records on equipment, services, etc. 6) Developing effective techniques for keeping operations personnel, upper-level management, and other concerned groups aware of maintenance activities. 7) Training maintenance staff and other concerned individuals to improve their skills and perform effectivity. 8) Reviewing the plans for new facilities, installation of new equipment, etc. 9) Implementing methods to improve the workspace safety and developing safety education related programs for maintenance staff. 10) Developing contract specifications and inspecting work performed by contractors to ensure compliance with contractual requirements.  Centralized maintenance: If maintenance dept. is in one place (separate office) is Centralized If maintenance dept. near or place in different dept, for individual equipment/service is De-Centralized Some of the benefits and drawbacks of centralized maintenance are as follows; Advantages: 1) More efficient compared to decentralized maintenance. 2) Fewer maintenance personnel required 3) More effective supervision 4) Greater use of special equipment and specialized maintenance persons. 5) Permits procurement of more modern facilities. Dis Advantages: 1) Requires more time getting to from the work area or job 2) No one individual becomes totally familiar with complex hardware or equipment 3) More difficult supervision because of remoteness of maintenance site from the centralized headquarters 4) Higher transportation cost due to remote maintenance work Maintenance management program improvement Improving a maintenance management program is a continuous process that requires progressive attitudes and active involvement. Nine -step approach for managing a maintenance program effectively is presented below: 1) Identify existing deficiencies: This can be accomplished through interviews with maintenance personnel and by examining in-house performance indicators. 2) Set maintenance goals: These goals take into consideration existing deficiencies and identify targets for improvement. 3) Establish priorities: List maintenance projects in order of savings or merit. 4) Establish performance measurement parameters: Develop a quantifiable measurement for each set goal, for example, number of jobs completed per week and percentage of cost on repair. 5) Establish short-and long ranges plans: The short-range plan focuses on high priority goals, usually within a one-year period. The long-range plan is more strategic in nature an identifies important goals to be reached within three to five years. 6) Document both long-and short-range plans: and forward copies to all concerned individuals. 7) Implement plan 8) Report status: Preparing a brief report periodically, say semi-annually, and forward it to all involved individuals. 9) Examine progress annually: Review progress at the end of each year with respect to stated goals. Develop a new short-range plan for the following year by considering the goals identified in the long-range plan and adjustment made to previous year’s planned schedule, resources, costs, and so on. Important Maintenance management principles: no. Principle Brief Description 1 Maximum productivity results when each This principle of scientific management formulated by involved person in an organization has a defined Frederick W. Tylor in the late nineteenth century remains task to perform in a definitive way and a definite an important factor in management. time. 2 Schedule control points effectively. Schedule control points at intervals such that the problems are detected in time, thus the scheduled completion of the job is not delayed. 3 Measurement comes before control When an individual is given a definitive task to accomplished using a good representation approach in a specified time, he/she becomes aware of management expectations. Control starts when managing supervisions compare the results against set goals. 4 The customer service relationship is the basis of A good maintenance service is an important factor in an effective maintenance organization maintenance facilities at an expected level efficiency. The term approach fostered by the organization setup is crucial to consistent, active control of maintenance activity. 5 Job control depends on definite, individual It is the responsibility of maintenance department to responsibility for each activity during the life develop, implement and provide operating support for the span of a work order. planning and scheduling of maintenance work. It is the responsibility of supervisory individuals to ensure proper and complete use of the system within sphere of control. 6 The optimal crew size is the minimum number Most tasks require only one individual. that can perform an assigned task effectively. Wednesday (Slide send by madam) Monday (online) Maintenance scheduling: The concept of scheduling can be applied to maintenance function for improving the operational availability of the equipment. To start with the maintenance scheduling, the two steps would be to know: 1) Number of machines to be maintained. 2) How to maintain them. - The maintenance schedule is to be prepared for all critical items which require to be maintained. - Initially, this exercise can be started with a few selected components of a machine and with experience the knowledge gained can be applied to the complete system. - The main objective of maintenance planning and scheduling is to raise the standards of the maintenance functions and make it cost effective. - In the case where the number of machines is high and maintenance scheduling is difficult, the use of computer is inevitable. - For the jobs not completed in time, rescheduling of the work can be done. - The concept of priorities is also an essential in case of scheduling. - The frequency of maintenance and criticality of operations are the key factors for establishing the priorities for the jobs. - Frequency indicates the relative importance of one equipment to another. - If the equipment becomes overdue for a certain number of jobs, it is treated critically important and the priorities must be set accordingly. - To minimize such situations, the scheduling must be done when it I due. - For effective results, over scheduling and under scheduling must be avoided. Types of scheduling: 1) Fixed scheduling: In case of fixed scheduling, the problems of backlogging is common when the work is not completed as per the schedule. 2) Dynamics scheduling: Dynamics scheduling take care of all practical constraints under all circumstances. Scheduling Process: 1) Prioritizing the maintenance work 2) Dealing with the emergencies 3) Maintenance calendars 4) Scheduling the backlog 5) Priority numbering system 6) Weekly and daily schedules 7) Controlling the backlog Cost reduction with maintenance planning and scheduling: - To cost reduction in maintenance, function with proper planning and scheduling of the work. - The first step in this direction is to utilize shutdown time of the equipment occurring due to the failures. This will depend on the following: 1) What type of work should be executed during shutdown. 2) When is the shutdown work list finalized. 3) How well is the shutdown work being planned. Work executed during breakdown: - Attempts must be made to minimize the shutdown period of time which ultimately will reduce the maintenance costs - During the shutdown period, jobs of minor nature, such as cleaning, repair and preventive maintenance, etc. should be undertaken. - When this basic principle is followed, it will result in reduced overtime, low contractor costs. - During major shutdown period maximum maintenance related works must be completed. - There is also pressure to postpone the scheduled minor repairs by executing this work during the major outage instead. - Minor downtime is important because it provides an opportunity to do preventive maintenance that cannot be done during operational time. Shutdown work finalization: - In the long-term plan, there should be fairly detailed lists of major works that must be done during each shutdown in the coming years. - For example: during boiler inspections, and electrical power distribution system inspections should be planned and estimated in long term plan. Maintenance Scheduling History: - Review of repair histories and making of accurate estimates of the time, materials and expenses that commonly occur with each project is essential. - Never estimate the budget for shutdowns during the budget figure from the past. This budget is based on reality. Planning shutdown work: - More work can be done by less people if it is properly planned. - The resulting repair quality will be better with the reduced costs. - This is due to the better instructions, and coordination of tools and materials and resources. - Each work order should be planned during execution. - This includes all the preventive maintenance work as well as repairs. The planning should include the following: 1) A clear scope of work required 2) An accurate estimate of manpower required 3) A detailed procedure of work 4) A list of tools and special equipment required 5) Schedule of execution of work 6) Safety and environmental hazard Comparison of Quality shutdown management versus the Poor shutdown approach Sr. no. Quality shutdown Poor shutdown 1 Controlled work list Unlimited work list 2 Limited overtime Unlimited overtime 3 Routine work done in schedule time Routine work done in over time 4 Timely availability of spare parts Untimely availability of spare parts 5 All work planned in advance Some work planned, most unplanned 6 Accurate schedule Unscheduled work 7 Add on work is rare Add on work is common 8 Planned, scheduled work get priority Planned, scheduled work gets cancelled 9 Budget based on reality Budget based on past information 10 Better documentation Poor documentation 11 Backlog minimum Backlog maximum 12 Absenteeism of workers is less Absenteeism of workers is more 13 Better accountability of work Poor accountability of work Maintenance Reliability & Probability: Reliability: - Reliability is the probability that an item will perform its stated mission satisfactorily for the given time period when used under the specified conditions. - The ability of a product, part, or a system to perform its intended function under a prescribed set condition. Reliability = Probability Improving Reliability: 1) Improve component design 2) Improve production &/or assembly techniques. 3) Improve tasting. 4) Use backup components 5) Improve preventive maintenance procedures. 6) Improve user education 7) Improve system design. Rule-1 If two or more events are dependent; Success: Probability that all events occur; Probability of success = Product of Probability of Events Example (Rule-1) Statement: Suppose room has two lamps, for proper lightening both lamps must work (success) when turned in. One lamp has probability of 0.90 and the other has probability of working of 0.8. Calculate the probability of both lamps will work? Solution: Diagram Lamp 1 Lamp 2 0.9 0.8 Probability of success = Product of Probability of Events = (0.9) × (0.8) Rule-2 If two or more events are independent; Success: Probability that at least 1 of events will occur Probability of success = Probability of either one + 1 minus that probability, multiplied by the other probability Example (Rule-2) Statement: There are two lamps in a room. When turned on, one has a probability of working of 0.90 and pother has probability of working of 0.80. Only a single lamp is needed to light for success. Calculate the probability of success Solution: Diagram Lamp 2 0.8 Lamp 1 0.9 Probability of success = Probability of either one + (1 minus that probability) × (other probability) = (0.90) + (1-0.90) × (0.80) = 0.98 Rule-3 If three events are involved. Success: Probability that at least 1 of them occur, Probability of success = (Probability of 1st one) + (1- Probability of 1st one) (Probability of 2nd one) + Product of (1- each of the first two probabilities) × (Probability of third event) Example (Rule-3) Statement: Three lamps have probability of 0.90. 0.80, 0.70 of lighting when turned on. Only one lighted lamp is needed for success, hence, two of the lamps are considered to be backups. Calculate probability of success? Diagram: Lamp 2 0.8 Lamp 1 0.9 Probability of success = (Probability of 1st one) + (1- Probability of 1st one) (Probability of 2nd one) + Product of (1- each of the first two probabilities) × (Probability of third event) Probability of success = (0.90) + (1-0.90) × (0.80) + {(1-0.90) × (1-0.80)} (0.70) Probability of success = 0.994  The bathtub curves Hypothetical Failure rate versus Time Infant mortality End of life wear-out Decreasing Failure rate Increasing failure rate Increased failure rate Normal life (useful life) Low “constant’ Failure rate Time Failure rate function of time: Three distinct regions: 1) Burn-in period 2) Useful life period 3) Wear out period 1) Burn-in Period - The burn in period is also known as “infant mortality period”, “break-in period,” or “debugging period” - During this time frame the hazard rate decrease and the failure occur due to causes as presented in following: Failure cause: 1) Poor quality control 5) Incorrect installation or setup 2) Inadequate materials 6) Poor manufacturing processes or tooling 3) Incorrect use procedure 7) Wrong handling 4) Poor test specifications 8) Poor technical representative training 9) - The infant mortality period is a time when the failure rate is dropping but is undesirable because a significant number of failures occur in a short time, causing early customers dissatisfaction and warranty expenses. - For a customer satisfaction viewpoint, infant mortalities are unacceptable. They cause “dead-on -arrival” products and undermine customer confidence. They are caused by defects designed into or built into a product. Therefore, to avoid infant mortalities, the product manufacturer must determine methods to eliminate the defects. Useful life period 1) In the useful life period, the hazard rate is constant, and the failures occur randomly or unpredictably. 2) Some of the causes of failures in this region includes: - Insufficient design margins - Incorrect use environments - Undetectable defects, human errors and unavoidable failures (i.e. ones that cannot be avoided by even the most effective preventive maintenance practices). In the mid-life of a product generally, once it reaches consumers. The failure rate is low and constant. Wear-out period - The wear out period begins when the item passes its useful life period. - During the wear-out period the hazard rate increases. - Some causes for the occurrence of wear out region failures are: a) Wear due to aging b) Inadequate or improper preventive maintenance c) Limited life components d) Wear due to friction e) Misalignments f) Corrosion and incorrect overhaul practices. - Wear out period failures can be reduced significantly by executing effective replacement and preventive maintenance policies and procedures. Terms: 1) MTBF 2) MTR 3) MTF 4) Failure rate 1) Mean time between failure (MTBF) It is sum of the operation periods divided by the number of observed failures. MTBF = θ = T/R T = Total time R = number of failures The MTBF value is equivalent to the expected number of operating hours before a product fails, or the “service life” 2) Mean time to repair (MTR) - It represents the average time required to repair a failed component or device. - To avoid MTR, many companies purchase spare products so that a replacement can be installed quickly. 3) Mean time to failure (MTF) - It is a basic measure of reliability for non-repairable systems. - It is the mean-time expected until the first failure of a piece of equipment. MTF = ϓ = T/N T = total time N = Number of units under test 4) Failure rate The failure rate is inverse of the MTBF λ= 1/ θ MTBF = θ = T/R Failure rate = R/T Exponential distribution: - Many probability distributions can be used to model the failure distribution. - A common model is the exponent failure distribution Once a MTBF is calculated, what is the probability that any one particular module will be operating at time equal to the MTBF? Solution: When t= MTBF R(t) = e-(t/MTBF) = e-(MTBF/MTBF) R(t) = e-1 = 0.3677 This tells us that the probability that any one particular module will survive to its calculated MTBF is only 36.8%. Assignment: By mean of extensive testing, a manufacturer has determined that its vacuum cleaner models have an expected life that is exponential with a mean of four years. Find the probability that one of these cleaners will have a life that ends: a) After the initial four years of service b) Before four year of service are completed c) Not before six year of service Non-destructive testing (NDT, to verify the quality of a product or system) - Non-destructive testing (NDT) uses the test methods to examine an object, material or system without impairing its future usefulness. - Non-destructive testing is often required to verify the quality of a product or system. Methods of NDT 1) AET- Acoustic emission testing 2) ART- Acoustic resonance testing 3) ET- Electromagnetic testing 4) IRT- Infrared testing 5) LT- Leak testing 6) MT- Magnetic particle testing 7) PT- Dye penetrant testing 8) RT- Radiographic testing 9) UT- Ultrasonic testing 10) VT- Visual testing (VI- Visual inspection) Most Common NDT methods 1) Visual testing (Visual inspection) 2) Dye liquid penetrate testing 3) Magnetic particle testing 4) Ultrasonic testing 5) Radiographic testing 1) Visual testing - Most basic and common inspection method. - Visual inspection, used in maintenance of facilities, mean inspection of equipment and structures using either or all raw human senses such as vision, hearing, touch, and smell and or/ any non-specialized inspection equipment. - Visual testing or inspection offers a wide range of options to secure proper system or product quality. - Portable video inspection unit with zoom allows inspection of large tanks and vessels, sewer lines. - Robotic crawlers permit observation in hazardous or tight areas, such as air ducts, reactors, pipelines. - Most discontinuities that are surface breaking or result in the deformation at the surface i.e. a) Cracks b) Holes c) Corrosion 2) Liquid penetrate inspection - Dye penetrate inspection (DPI) also called as liquid Penetrant Inspection (LPI) or Penetrate test (PT) is fast, economical and widely used non-destructive test method to detect surface-breaking dis-continuities in all non- porous materials (metals, plastics, or ceramic) - DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface- breaking discontinuities. - Penetrate may be applied to the test component by dipping, spraying, or brushing. - After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied - The developer helps to draw penetrant out of the flaw where an invisible indication becomes visible to the inspector. - Inspection is performed under the ultraviolet or white light, depending upon the type of dye used-Fluorescent on non-fluorescent. Steps of liquid penetrate inspection a) Cleaning and drying of test surface b) Application of penetrant to test surface c) Removal of penetrant from test surface d) Application of developer 3) Magnetic particle inspection - Magnetic particle inspection (MPI) also sometimes called as magnetic test (MT) is a non-destructive test method for the detection of surface and sub-surface discontinuities in ferrous materials such as iron, nickel, cobalt and some of their alloys - Magnet is placed around solid - The magnetic lines of force run from one pole to the other and the poles are positioned such that any flaws present run normal to these lines of force. - The presence of a surface or sub-surface discontinuity in the material allows the magnetic flux to leak. - Ferrous iron particles are then applied to the part. Diagram - If an area of flux leakage is present the particles will be attracted to this area. The particles will build up at the are of leakage and from what is known as an indication. - The indication can then be evaluated to determine what it is, what may have caused it, and what action should be taken, if any. 4) Ultrasonic testing - High frequency sound waves are introduced into a material, and they are reflected back from surface or flaws. - Reflected sound energy is displayed versus time, and inspector can visualize a cross section of the specimen showing the depth of features that reflect the sound. 5) Radiography testing - Radiography can be used to obtain permanent image of surface and sub-surface (embedded) discontinuities. - The same discontinuities can be radiographed again after a period of service life and the radiographs can be compared to measure the change in the size and shape of the discontinuity - The part is placed between the radiation sources and a piece of film. The part will stop some of the radiation. - Thicker and more dense area will stop more of the radiation. The film darkness (density) will vary with the amount of radiation reaching the film through the test object. These difference in “absorption” can be recorded on film, or electronically. Diagram - The energy of the radiation affects its penetrating power. Higher energy radiation can penetrate thicker and dense materials. - Common applications of NDT 1) Inspection of raw products 2) Inspection following secondary processing 3) In-service damage inspection Inspection of raw products 1) Forgings (raw form) 2) Casting 3) Extrusion etc. Inspection following secondary processing 1) Machining 2) Welding 3) Grinding 4) Heat treating 5) Plating etc. Inspection for In-service damage inspection 1) Cracking 2) Corrosion 3) Erosion/wear 4) Heat damage etc. Wire rope inspection: - Electromagnetic devices and visual inspections are used to find broken wire and other damages to the wire rope that is used in chair lifts, cranes and other lifting devices. Storage tank inspection: - Robotics crawlers use ultrasound to inspect the walls of large above ground tanks for sings of thinning due to corrosion. - Cameras are used to inspect underground storage tanks for damage. Aircraft inspection - Non-destructive testing is used extensively during the manufacturing of aircraft. - NDT is also used to find cracks and corrosion damage during operation of the aircraft. Jet Engine inspection: - Aircraft engines are overhaul after being in service for a period of time. - They are completely dissembled, cleaned, inspected and then reassemble. - Fluorescent penetrant inspection is used to check many of the parts for cracking. Pressure vessel inspection: - The failure of pressure vessel results in the rapid release of large amount of energy. To protect these dangerous events, the tanks are inspected using radiography and ultrasonic testing. Rail inspection: - Special cars are used to inspect thousands of miles of rails track to find crack that could lead to a derailment. - The heavy loads that trains place on the railroad tracks can result in the formation of crack in the rail. If these cracks are not detected, they can lead to a derailment. - Special rails car equipped with NDT equipment are used to detect rail defects before they are big enough to cause serious problems. Bridge inspection: - The US has 578,000 highway bridge. - Corrosion, cracking and other damage can all effect on bridge’s performance. - The collapse of the silver bridge in 1967 resulted in loss of 47 lives. - Bridge get a visual inspection about every 2 years. Pipeline inspection: - NDT is used to inspect to prevent leaks that could damage the environment. - Visual inspection, radiography and electromagnetic testing are some of the NDT methods used. Maintenance of pumps Slides provided by madam. Lubrication program Meaning of lubrication - Friction- is created by when there is relative motion between two surfaces. - Resistance to motion is define as friction - Lubrication is use of a material between surfaces to reduce friction. - Any material used is called a lubricant Methods of lubrication Two main methods: 1) Hydrodynamic lubrication 2) Boundary lubrication Hydrodynamic lubrication - Any material used is called a lubricant - Also called complete or full flow - Occur when two surfaces re completely separated by a fluid film Boundary lubrication - Occurs when hydrodynamic lubrication fails - Two surfaces mostly are in contact with each other even through a fluid is present - Boundary lubricants generally have long, straight, polar molecules, which will readily attach themselves to the metal surfaces. High speed/high load as surface slide over another surface (Diagram) Type of lubricants-Physical 1) Liquid: - Typical lubricants are liquid/fluids - Mineral oil or synthetic oils 2) Solid - Graphite - Molybdenum disulfide 3) Gases - Compressed air Typical lubricants - Engine oils - Gear oils - Turbine oils - Hydraulic oils - Metal working oils Typical lubricants-Application 1) Rust preventives 2) Heat transfer oils 3) Refrigeration oils 4) Rubber Process oils 5) Ink process oils Lubricant- Components 1) Base oils Base fluids are essentially obtained from two main sources: a) Petroleum lubricating oils are made from the higher boiling portion of the crude oil that remains after removal of lighter fractions. The refining of petroleum crude oil (Petroleum base oils) b) A product prepared by chemical reaction of lower molecular weight materials to produce fluid that designed to provide certain predictable properties (synthetic base oils) Function of Lubricant: - Lubricate- Reduce friction - Cooling- Heat transfer - Cleaning- Detergency - Noise pollution- damping - Sealing- prevent leakage - Protection- Prevent wear a) Lubricate-Reduce friction The effect of friction - Metal to metal contact - Lead to metal contact - Generates heat - Results in power loss Lubricant reduces friction by forming a film b) Cooling - When fuel burnt in engine - Lube oil removes heat from all areas and brings it to the engine sump. - Improper cooling can lead to over-heating, lead to wear, distortion and failure c) Cleaning: Flushes the entire system removing - Soot - Deposits - Aids - Ware products - Moisture Remove external contaminants dust, moisture (external) d) Noise reduction Reduce reduction By preventing metal to metal contact e) Sealing To provide sealing action i.e. the lubricating oil helps the piston rings to maintain an effective seal against the high- pressure gases in the cylinder from leaking out into the crankcase. f) Protection Very important to increase life of component and equipment Protect from wear and tear. Properties of Lubricants - Kinematic viscosity - Viscosity index - Pour point - Flash point - Total base number (TBN) Kinematic viscosity - Measure of internal resistance to flow - Decrease with increase in temperature - Important in lubricant section - Measured in Centi-Poise (cSt) Viscosity index - Measure of fluids change of viscosity with temperature - High the value of VI lower will be the change of viscosity with temperature - Indicator of temperature range of operations Pour point - Lowest temperature at which the fluid will flow - Indicates lowest operating temperature - Measured in Celsius Flash point - The flash point is the lowest temperature at which there will be enough flammable vapor to support combustion when an ignition sources is applied - Lowest temperature at which the vapor above liquid will ignite under flame - Indicated safe maximum temperature of operation - Indicator of volatility - Measure in Celsius Total base number (TBN) - Measured the acid neutralizing reserve in oil - Important for deciding discard of oil - Decrease due to:. Oxidation of oil. Water contamination. Fuel contamination - Measured in mg KOH/gm of oil - In chemistry, acid value (or “neutralization number” or “acidity”) is the mass of potassium hydroxide (KOH) in milligram that is required to neutralize 1-gram chemical substance. What are additives: - Chemical compounds that improve the lubricant performance of base oil - Enhance existing property - Suppress undesirable property - Impact new property - Comprise up to 5% by weight of some oil What additives do in Engine oils - Protect metal surfaces - Rings, Bearing, gears, etc. - Extend the range of lubricant applicability - Extend lubricant life Surface protective additives 1) Corrosion & rust inhibitor 2) Anti-wear 3) Detergent 4) Dispersant 5) Friction modifier