Concepts Of Modern Maintenance Management 71123u

CONCEPTS OF MODERN MAINTENANCE MANAGEMENT

INTRODUCTION The human civilization has come a long way from the early agrarian societies. The modern industries with mass production capacities have almost put an end to the cottage industries.Machines have long back taken the place of human hands.These modern industries have given us bulk production for the ever increasing population at economic costs. The industrial revolution saw the advent of complex machinery each fitted with thousands of different static and moving parts.Simple controls have now developed into fully automated systems run not by humans but by computers. Today the industrial world is highly interdependent and competitive.High cost of production or a day of production lost has a high impact on the company.In this challenging scenario, today the maintenance managers have an unenviable and daunting task of maintaining all the equipments and systems in the best of health to meet the needs of the industry.This is possible only by adopting the best of modern maintenance management techniques. SELECTION OF CORRECT EQUIPMENTS This is extremely important from the viewpoint of future maintenance.Unless the equipment /system chosen at design stage is suitable for the environment and duty of application, it is bound to give the maintenance team a tough time and recurring problems. It is,therefore,essential to consider all the design parameters while selecting and installing an equipment. New technologies are being introduced in all products and equipments today to reduce the maintenance requirements or make them maintenance free.For example,earlier we had to check and add water often in our car radiator but today coolant is required to be added only during servicing.Also sealed maintenance free batteries have replaced the old lead-acid battries which required topping up of distilled water regularly.Maintenance free items are designed for a certain service life and are to be replaced after their useful service life. The concept of Life Cycle Cost (LCC) has also gained ground in the western world and private sector in selecting equipments.Life Cycle Cost means the expected costs to be incurred during the design life of the equipment and consists of initial cost,maintenance cost,running cost etc.Here, instead of only the initial capital cost , the life cycle cost is considered for selecting an equipment.To take a real life example, suppose we want to buy a car,then if we compare cars not only on the basis of initial cost but also give due consideration to fuel efficiency,cost of spare parts etc then our selection is based on the concept of life cycle cost.Unfortunately,this concept is yet to be brought into practice by Indian Public Sector where selection of new equipments are solely based on the lowest capital cost which may not prove to be economical in the long run. Proper installation and commissioning is also equally important. If an electrical is not properly tested or a pump is having high vibration at commissioning stage ,it surely requires corrective action at the beginning instead of waiting for failure.

COSTS INVOLVED Let us have a look at the various costs involved in the maintenance activity:  Manpower costs : By way of salary for company maintenance personnel or payments towards contractual manpower services.  Cost of Spare Parts and Consumables  Cost of production loss due to breakdown  Insurance : Generally more insurance is required to be paid if the company has a weak maintenance system as in this case risks are more. Every company/enterprise is basically a business unit and hence it has to analyse all costs and try to minimize them for achieving competitive rates of production.It has ,therefore,to optimize the maintenance costs.The following graph shows :

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As maintenance cost increases , the cost of production loss falls. The Total Cost (Maintenance Cost + Cost of Production Loss) decreases with maintenance upto point A and then it again starts to increase. The maintenance objective is to achieve point A which has the minimum total cost

MAINTENANCE SYSTEMS The following are the types of maintenance systems in practice around the world :  Breakdown Maintenance : It is basically a philosophy in which no maintenance is done unless a machine breaks down.It may also be termed as repair based maintenance.An example of breakdown maintenance is that our car breaks down on the road and we call a mechanic to repair it.

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Breakdown maintenance philosophy is generally adopted by companies for small and non-critical normal equipments where breakdown does not have a significant impact on production and cost of repair is low. Planned or Preventive maintenance : This is a widely practiced maintenance system.Here maintenance of equipments is carried out in accordance to predrawn maintenance schedules. These maintenance schedules are either ‘Calendar Based’ like weekly,monthly,quarterly,yearly etc. or “Run Hour’ based eg. 500 hours maintenance.An extract from Maruti car preventive maintenance chart is shown below as an example : Maintenance service 500 km 2000 km 5000 km 20000 km 40000 km Water pump drive belt Adjust Adjust Adjust Adjust Replace Engine coolant Inspect Inspect Inspect Replace Replace Engine oil Inspect Inspect Replace Replace Replace Engine oil filter Inspect Inspect Replace Replace Replace Spark plugs Clean Replace Replace Here the maintenance costs are quite high which is mainly the cost of maintenance manpower and spares parts consumed. By carefully scheduling and adhering to it the chances of pre-mature failures and major breakdowns can be minimized.This philosophy is mainly adopted for all critical and essential equipments. Predictive Maintenance : In this maintenance system condition monitoring is carried out for important parameters of a machine such as temperatures,vibrations,insulation resistance of motors etc. to assess the internal health of machines and maintenance is done to pre-empt any impending failures.Examples can be on-line vibration and temperature monitoring systems or condition based replacement of lube oil. For predictive maintenance expensive systems like vibration analysers,temperature monitors ,oil testing apparatus are required and hence this maintenance philosophy is adopted only for critical and some essential equipments. This is better than preventive maintenance as we save on cost of maintenance manhours and spare parts to some extent.This also saves us from sudden failures leading to production loss.Modern techniques such as infrared thermography and partial discharge analysis for HT machines are fast gaining ground. These are on-line non-destructive tests which help in health assessment of electrical systems and allow us to prevent catastrophic failures. Corrective Maintenance : It is basically maintenance required to restore the machine to its original health after long periods of use and resulting wear and tear.Planned overhauls come under this category.Suppose our car has run a lakh kms,then it needs engine overhaul to deliver proper power and fuel efficiency.This is an example of corrective maintenance. Total Productive Maintenance (TPM) : This concept was first introduced in Japan.It is generally seen that the plant manpower is divided into two groups : operator group and maintenance group.The operators are not concerned about the machine health as it is the baby of maintenance group.TPM aims to make the operator group responsible for the first level maintenance of the machinery they

operate like checking of oil levels, vibrations, temperatures, leakages etc.The major challenge here is changing the mindset and skill level of the operators. TPM strives to achieve overall equipment effectiveness through a combination of availability,performance efficiency and rate of quality products. CATEGORIZATION OF EQUIPMENTS As we have seen each type of maintenance philosophy incurs different costs to the enterprise.It is clear that any one type of maintenance philosophy cannot be applied economically to all categories of equipments.Hence,it is necessary to categorize the plant equipments as follows :  Critical  Essential  Important  Normal

After categorizing the equipment, a VEIN analysis chart can be plotted between degree of criticality of an equipment and type of maintenance requirements as shown below : Critical Essential Important Normal

Basically one has to distribute the equipment into a mix of breakdown maintenance (BM) and planned maintenance (PM).The planned maintenance can be further sub-divided into preventive and predictive maintenance systems depending upon the degree of criticality of the equipment.

If we look at the VEIN chart we observe that the Critical equipments have a small percentage of breakdown maintenance ( as breakdowns cannot be totally eliminated) and a high share of planned maintenance (PM).This trend reverses for equipments under the Normal category.The Essential and Important category equipments are in between. This kind of mix has to be decided upon as the direct cost of PM is high but the consequential cost of BM is also high. On this basis an organization can save on unnecessary PM costs and give the plant high serviceability and availability.This has to be continually updated with the received along with the defect analysis and the down time analysis reports. MTBF AND MTTR These are two important concepts that every maintenance man must understand and analyse. MTBF(Mean Time Between Failures) is basically the mean time between various breakdowns(failures) of a particular equipment over a certain period of time.A low value of MTBF indicates frequent breakdowns of the equipment.The aim is to achieve a high MTBF. MTTR(Mean Time To Repair) is the mean of time (calculated over a certain period of time, say one year) for which the said equipment was under repair after breakdown.It gives an idea as to how quickly the equipment could be repaired.A low MTTR value is desirable.

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The above diagram shows the following sequence of operation for an equipment with respect to time :

Breakdown at Point A Repair from A to B In Operation from B to C Again Breakdown at C Repair from C to D In Operation from D to E Again Breakdown at E Repair from E to F From the above we can calculate MTBF and MTTR for a period of time from A to F. SPARE PARTS MANAGEMENT Spare parts management is an important job parameter for a Maintenance Manager. Cost of spares for about 60 to 80 % of total maintenance costs hence optimizing the spare parts inventory is of utmost importance. Before the era of computers, techniques like ABC analysis were employed as manually keeping track of each spare part was next to impossible. However, computers are now helping in the field of inventory management in a big way. The following needs to be done in this area of maintenance management :  Each spare part must be uniquely identified through some effective coding system  Spare parts linked preventive maintenance schedules must be drawn  Spare parts must be categorized as 1. Regular spares: Required for scheduled maintenance after a fixed interval. For example, six monthly replacement of lube oil filters. 2. One-off spares : These spares will be required mostly if some defect occurs. Most of the electrical and electronics spares fall under this category. For example, if fuses are blown as a result of some short-circuit, new fuses will be required for replacement after attending to the fault. 3. Insurance spares : These are very high value and low consumption spares which may not be required for quite some time but their stockout cost implications are very high.The company can have some sort of rate contract with the OEM (Original Equipment Manufacturer) for supplying such items on need basis. 

The company can also have some float assemblies like turbines,motors etc., depending on their population, to avoid production loss during scheduled overhauls.

THE HUMAN ELEMENT The maintenance workforce is the most vital element which can decide the success or failure of a well conceived maintenance plan. In multinational and private sector companies each and every employee has got well defined job responsibilities based on scientific work studies and he/she is

well groomed/trained for the job. The Public Sector companies are mostly lacking in this basic area. As downsizing is normally not possible in government/public sector enterprises ,as a minimum the following measures shall be adopted for better productivity :  Clear cut job assignments and responsibilities  Measurable targets  Performance linked promotions and monetary incentives for motivation  Proper knowledge and skill training to handle the assignment  Building cost consciousness and safety awareness ROLE OF COMPUTERS Various Computerized Maintenance Management Systems are now available in the market. These vary from SAP like integrated ERP packages to small tailor made softwares and cover all dimensions of modern maintenance management such as  Preventive maintenance scheduling  Inventory management  Equipment availability and history records  Maintenance costs  Failure analysis (MTBF,MTTR) By proper customization of these software based Maintenance Management Systems and applying modern maintenance management techniques, the maintenance departments can streamline their operations and serve the industry in a more efficient, productive and cost effective manner.