Maintenance Modules GROUP MEMBERS AMARASENA R.G.C. : D DAYANI. J : V NUWAN.U.P.A : H PAHATHKUMBURE. K.M.D.K.B : P THAASAN S. : B WICKRAMARATHNE T. I. :061060T

What is Maintenance? The maintenance department is one of the greatest levers of profitability that any capital intensive organization has. An average of 40 – 50% of a capital intensive industries operating budget is consumed by maintenance expenditure. With the advances today in technology affecting maintenance this figure can be greatly reduced. As such maintenance is often an organizations largest single controllable expense.

Maintenance Maintenance Types PlannedUnplanned

Unplanned maintenance Reparation will be conducted after the equipment fails Used when the equipment failure does not considerably affect the operations or generate any notable loss other than the repair cost

Unplanned Maintenance cont… Advantages Low maintenance cost Low maintenance staff Disadvantages High down time Lower operational efficiency Low quality outputs Impaired health & safety conditions

Planned Maintenance Planned maintenance is organized and executed with planning and control by utilizing the application of recorded data. It encompasses condition based maintenance, which is planned and progressed information received about a system or company structure's condition. This information is gleaned from routine or continuous monitoring processes and preventative maintenance.

Advantages of planned maintenance Releases front-line foremen from major planning duties and allows them more time to supervise their crews. Provides procedures to plan, execute, monitor and control maintenance resources. Reduces delays in waiting for men, material, tools after a job is in progress. Provides for systematic collection of materials prior to planned jobs. Provides procedures to implement and continue a PM program

Planned Maintenance types Preventive Maintenance Corrective Maintenance

Preventive Maintenance Preventative maintenance is carried out at predetermined intervals or according to prescribed criteria, with the intention of reducing the probability of failure or the performance degradation of a system. PM includes painting, lubrication, cleaning, adjusting, and minor component replacement to extend the life of equipment and facilities. Purpose is to minimize breakdowns and excessive depreciation. Neither equipment nor facilities should be allowed to go to the breaking point. To minimize the risk, has to be carefully planned and carried out by well-trained and motivated workers.

Advantages of preventive maintenance Improved system reliability. Decreased cost of replacement. Decreased system downtime. Better spares inventory management.

Corrective maintenance Maintenance actions carried out to restore a item that can be failed in to a specified condition Improve equipments enabling the preventive maintenance to be carried out easily Equipment with design weakness will be redesigned

Advantages of Corrective Maintenance  Enhanced component life time  Enable prior corrective actions  Lower equipment downtime  Quality improvement of the products  Enhanced the safety  Strengthened worker moral  Save energy

Disadvantages of Corrective Maintenance  Higher investment in diagnostic equipment  Higher investment for training

Corrective Maintenance Types

Maintenance actions based on actual conditions Reparation of a machine which gives an unusual sound can be identified as an example Can identify and rectify problems at an early stage and can improve machinery reliability Condition Based Maintenance (Predictive Maintenance)

Opportunistic Maintenance  Reparation of the components which are found to be defective or needs replacement in the immediate future  The components will be identified during the maintenance of a sub- system or a module

Opportunistic Maintenance cont… As an example, identifying and rectifying a defective feeder, during the maintenance actions carried out for a faulty stitch cam in a knitting machine

Routine Maintenance Includes activities which are perform in planned basis to maintain and protect the conditions of equipments /processes Most simplest type of planned maintenance Oiling knitting machines in can be identified as an example

Design Out Maintenance Design modifications to stop the failure from occurring Usually conducted based on the past experiences As an example; a design modifications conducted to a yarn feeding finger in a knitting machine to avoid having plating effect. The identification the fault and designing the finger will be conducted based on the past experience

Other Maintenance Types

Reactive Maintenance No measures are taken to maintain the equipment because the designer should ensure that the design will reach it’s life time

Reactive Maintenance cont… Advantages Lower cost Less staff Disadvantages Increased unplanned downtime cost Repair / replacement of equipment cost Other equipment or process damage due to the equipment failure

Maintenance Prevention Indicates a design of a new equipment Drawbacks of existing machines are studied before designing the new equipment

Maintenance Prevention cont… Rieter, developed modern rotor machines with innovative bearing and lubrication techniques This reduce the maintenance requirements in the modern machines than in the conventional rotor machines

Maintenance Prevention cont… Advantages Lower maintenance cost Lower machine downtime Disadvantages Higher investment for training Higher investment for equipments and technology

Maintenance Models

Replacement Why? Company Employee Target Achievemen t Employee & Machines

Replacement Employees Machines

Immediate replacement after failing With continuous failure With expectation of failure

Age Replacement Model Time Age of Machine TTTT  For the equipments of which cost of repair is higher if it fails while operating  Cost of maintenance involves  Down time loss  Cost due to low efficiency  Replacement cost  Down time cost

Assumptions of the Model  Cost of maintaining the equipment increases as the equipment ages  The equipment used is operating continuously or intermittently  Down time for repair and maintenance is ignored  The planning horizon is infinite  Every new piece of equipment has identical characteristics

Calculating the ‘T’ value Total cost = Replacement cost + Maintenance cost – salvage value G(t) = K + C(t) – S(t) Time Cost Breakdown Cost Maintenance Cost Total Cost Salvage Value T Minimum total cost

Advantages and Disadvantages of the Age Replacement Model Advantages Simple and basic calculation Once calculation is done it can be used for long time until the characteristics of the product is changed Disadvantages Not suitable for the products of which characteristics are changed time to time This model does not consider about the unplanned breakdowns of machines

Applications of the model in Textile and Clothing Industry For the vehicles used in both industries For the changing time of auto cutter unless knife is broken Replacement of sewing machines

Planned replacement on uncertainty Replacing before it fails

Is it worthwhile doing a planned replacement? How likely it will happen? How do we quantify it?

Probability Impact

Planned replacement without a review Consequences might be not worthwhile No advantage in avoiding the failure Throw out unused life away Get nothing

Planned replacement should reduce the chances of a failure Replaced part or person should perform better than the previous or be more reliable For this : Reliability Failure Replaced item Old item

Planned replacement Individual replacement Group replacement

Questions ???

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