Introduction:Plant maintenance is an important service function of an efficient production system.It helps in maintaining and increasing the operational efficiency of plant facilities.Maintenance is the procedure of finding the faults in any equipment/Machine and also removal of fault.It may be before the breakdown or after the breakdown.
Plant maintenance usually refers to the methods, strategies, and practices used to keep an industrial factory running efficiently. This can include anything from regular checks of equipment to make sure they are functioning properly.The general aim of plant maintenance is to create a productive working environment that is also safe for workers.
Maintenance Objectives:To increase functional reliability of production facilities.To maximize the useful life of the equipment.To maximize production capacity from the given equipment.To minimize the total production cost.To minimize the frequency of interruption in production by reducing breakdowns.To enhance the safety of the manpower.
Importance of maintenanceIt helps in identify the cause of failure , e.g whether the failure is due to design defect, or a wear out failure.It also helps in deciding the type of maintenance and maintenance decision like replace and repair.It provides the necessary information regarding the life and reliability of the equipment.With the help of this tool spare parts management got initiated.
Planned Maintenance- In planned maintenance the maintenance action is carried outwith some fore thoughts, prior planning , record keeping andcontrol action. These can be further classified as :- Preventive maintenance Corrective maintenance Predictive maintenance
It is based upon the principle that ‘prevention is better than cure’. It is a set of activities that are performed on plant equipment, machinery, and systems before the occurrence of a failure in order to protect them and to prevent or eliminate any degradation in their operating conditions. Or the maintenance carried out at predetermined intervals or according to prescribed criteria and intended to reduce the probability of failure or the degradation of the functioning and the effects limited. It has three types Running maintenance Scheduled maintenance Shut down maintenance
Running maintenance:Running maintenance which includes those maintenance activities that are carried out while the machine or equipment is running.Example – lubrication, adjustment of nuts and screws, tightening of loose nut and bolts.
Scheduled Maintenance:Scheduled Maintenance is any variety of scheduled maintenance to an object or item of equipment.Specifically, Planned Maintenance is a scheduled service visit carried out by a competent and suitable agent, to ensure that an item of equipment is operating correctly and to therefore avoid any unscheduled breakdown and downtime.Good example of PM program is car maintenance. After so many kilometers or miles oil should be changed, parts renewed.
Shut Down Maintenance:Which is a set of preventive maintenance activities that are carried out when the production line is in total stoppage situation.These are performed generally after three or six months.These involves the inspection of plant items which are known or suspected to occur.
Corrective maintenance: In this type, actions such as repair, replacement, or restore will be carried out after the occurrence of a failure in order to eliminate the source of this failure or reduce the frequency of its occurrence. It also include the different types of actions like typical adjustment of redesign equipment.The difference between corrective maintenance and preventive maintenance is that for the corrective maintenance, the failure should occur before any corrective action is taken. It is of two types 1. Breakdown maintenance 2. Shutdown maintenance
Breakdown Maintenance:It is an emergency based policy in which the plant or equipment is operated until it fails and then it is brought back into running condition by repair.The maintenance staff locate any mechanical, electrical or any other fault to correct it immediately.It is feasible for the small factories where 1. There are few types of equipment. 2. Machine and equipments are simple and does not require any specialist. 3. Where sudden failure does not cause any serious financial loss.
Predictive maintenance:As the names implies it involves the prediction of the failure before it occurs, identifying the root cause for those failures symptoms and eliminating those causes before they result in extensive damage of the equipment.Type of maintenance performed continuously or at intervals according to the requirements to diagnose and monitor a condition or system. Also called condition based maintenance.
Unplanned Maintenance:Maintenance action which is carried out without any fore thoughts or prior planning is called unplanned maintenance.Emergency maintenance is one of the example of unplanned maintenance.In this type of maintenance the maintenance action is executed with the help of all available maintenance resources in least possible time, without any major time lag.Examples are gas leakage in chemical plant, fire hazards, breakdown of boiler, turbine etc.
General classification Maintenance problem. Mechanical Failure Worn out bushes and bearings and other moving parts. Fatigue of machine members Creep of material at high temp Excessive forced vibration, misalignments etc. Thermal Failure Overheating of the component Lack of lubrication Inadequate of cooling Electrical insulation failure Chemical Failure Highly corrosive fluids containing abrasive particles Failure of protective linings like glass , rubber etc.
Classification maintenance problembased on time span: Short run production problemMaintenance problem which are carried out in a sort period of time are known as short run production system. It may be hourly, daily ,weekly and monthly.Example:-Hourly- inspection of correct lubricant, level of coolant, sharpness of cutting tool.Daily- cleaning of m/c, tightening of nuts, correct cooling, inspection of various indicators, minor adjustment of parts.Weekly- Major adjustment, lubrication, tightening of parts.Monthly- checking for insulation, corrosion, safety guards, checking of worn-out and distorted parts.
1. Job identification by preparing offacility engineerThe very first step of PMP is to prepare the facility register which defines that what to be maintained.2. Preparation of maintenance schedule In this step we prepare a maintenance schedule. It is simply a comprehensive list of all the incident and their time of incidence. It gives the useful information regarding the method, time and place of maintenance work, besides it also provides secondary information about maintenance man power requirement etc. It gives the various details regarding maintenance like what, when, how, where.
3. Preparation of history cardIt not only gives the useful information about the result of maintenance events but also furnishes the essential details regarding the uses of machines, free of failures and failure modes.4. Preparation of Job specification In this step the job specification is prepared. It is simply a document which provide the essential information regarding the maintenance work to be done. In general practice these job details are specifications compiled from maintenance schedules. They are a means of communicating the engineer’s requirement to guide the workers. They are prepared separately for each job.
5. Preparation of maintenanceProgrammingIt is a sequential list which allocates specific maintenance work to a specific period.In order to apply the job specification, the maintenance programme is generally prepared for long run when the machines/ equipment are to be inspected.It is not a good practice because an industry can not prepare a long run production well in advance since too many factors arise and they will result into change in production and maintenance requirement.It presents a overall picture of present and future maintenance commitments.
6. Preparation of weekly/Monthlymaintenance programmesThe next step under plant maintenance procedure is to prepare the weekly/ Monthly maintenance programmes. The maintenance programmes include the following topics. 1. Reconditioning or replacing the lubricating oil 2. Repairing and replacing worn out parts and tools etc 3. Checking all the electrical connections of the system 4. Checking the control system 5. Checking the performance of each parts. 6. Cleaning the interior parts like spark plugs, filters radiators, crankcase, cylinders etc. 7. It will lie under the long run maintenance programmes.
7. Preparing of inspection reportThis step is followed after the maintenance programme is over. This is simply a document which furnishes the useful information about the maintenance inspections which were performed in the past.8. Preparing of maintenance request The next step under plant maintenance procedure is to preparation of maintenance request. It is simply a document or various maintenance suggestions and recommendation given by the inspection report. Suggestions are the useful feedback information that comes from users end workers.
9. Feedback mechanismIn the last step the application of corrective and control actions are available on the basis of feedback mechanism. These corrective actions should be applied to respective plant facilities at the initial stage of maintenance planning or design.
Schedules of preventive maintenance:It is simply a comprehensive list of all the incident and their time of incident. It gives the following useful information regarding the maintenance work. i. What is to be done or maintained? ii. How is to be maintained? iii. When is to be maintained? Besides this it may also provide the secondary information regarding the place of maintenance and maintenance requirement.
Maintenance Strategy :A maintenance strategy defines the rules for the sequence of planned maintenance work. It contains general scheduling information, and can therefore be assigned to as many maintenance task lists (PM task lists) and maintenance plans as required. A maintenance strategy contains maintenance packages in which the following information is defined:The cycle in which the individual work should be performed (for example, every two months, every 3,106.86 miles, every 500 operating hours)Other data which affects scheduling
Structure:A maintenance strategy consists of:Strategy header: Name of the strategy,Scheduling parameters: Contain the scheduling data forthe respective maintenance strategy, which influence thescheduling of maintenance plans.Scheduling indicatorsMaintenance packages
Scheduling Indicators:Within a maintenance strategy, you can use differentscheduling indicators to specify the type of scheduling yourequire or to define a cycle set: Time-based (for example, every 30 days) Time-based by key date (for example, every 30 days on the30th day of the month) Time-based by factory calendar (for example, every 30working days) Performance-based (for example, every 50 operating hours)
Maintenance Packages:Maintenance activities that must be performed at a particular date or point in time are combined into maintenance packages
Total Productive Maintenance (TPM) Total productive maintenance (TPM) originated in Japan in 1971 as a method for improved machine availability through better utilization of maintenance and production resources It can be considered as the medical science of machines. Total Productive Maintenance (TPM) is a maintenance program which involves a newly defined concept for maintaining plants and equipment. The goal of the TPM program is to markedly increase production while, at the same time, increasing employee morale and job satisfaction.
TPM brings maintenance into focus as a necessary and vitally important part of the business. It is no longer regarded as a non-profit activity. Down time for maintenance is scheduled as a part of the manufacturing day and, in some cases, as an integral part of the manufacturing process. The goal is to hold emergency and unscheduled maintenance to a minimum.
Why TPM :TPM was introduced to achieve the following objectives. The important ones are listed below.Avoid wastage in a quickly changing economic environment.Producing goods without reducing product quality.Reduce cost.Produce a low batch quantity at the earliest possible time.Goods send to the customers must be non defective.
Conclusion:Today, with competition in industry at an all time high, TPM may be the only thing that stands between success and total failure for some companies.It has been proven to be a program that works. It can be adapted to work not only in industrial plants, but in construction, building maintenance, transportation, and in a variety of other situations.If everyone involved in a TPM program does his or her part, an unusually high rate of return compared to resources invested may be expected.