PRODUCTIONManagementReliability,

Maintenance

Group members.. Shivani Sahu – 121 Afzal Shaikh – 132 Nazneen Sheikh – 137 Raviraj Shetty - 140 Gulmohit Singh – 148 Yogesh Singh - 151 Sandesh Sonawane – 154 Lydia Thomson - 159

Maintenance • Maintenance management is concerned with the

direction and organisation of resources in order to control (improve) the availability and performance of the industrial plants to some specified level.

• Maintenance is defined also as that function of production management concerned with the day to day problem of keeping the physical plant in good operating condition

Plant Maintenance

• Is repairing of the machine at planned intervals so that sudden breakdowns could be prevented and costly downtime avoided. This work is generally done when the shop can spare the machine for repairs, generally during off shift hours, Sundays and holidays.– Lubrication and Inspection are two constituents of

PM

OBJECTIVE

– Get equipment back into operation as quickly as possible.

– Control cost of repairs crews.– Control cost of the operation of repair shops.– Control the investment in replacement spare parts.– Control the investment in standby or backup

machines.– Perform the appropriate amount of repairs at each

malfunction.

Advantages of PM

• Greater safety to workers• Reduction in production down time• Lesser expenditure on repairs due to fewer repetitive

and large scale repairs• Less spare parts• Prolongs the life of the machine• Maintains quality and continuity of production

Disadvantages of PM

• High control on records and analysis, planning & scheduling

• Monitoring of parameters like temperature, lubrication, noise, corrosion ,leaks etc are high. The equipments to do that also are costly.

• Optimum PM is required, hence correct judgement is needed. Too much or too little is not good.

SCOPE OF MAINTENANCE SCOPE OF MAINTENANCE

• Primary functions:-Primary functions:-• Maintenance of existing plant and equipment's.• Maintenance of existing plant buildings and grounds.• Equipment inspection and lubrication.• Utilities generation and distribution.

• Secondary functions:-Secondary functions:-• Store keeping • Plant protection including fire protection.• Waste disposal• Salvage.

Importance of maintenanceImportance of maintenance

• Dependability of services is on of the performance measures.

• Maintenance is an important factor in quality assurance.

• It helps company by offering protection in case of lengthy equipment

• Important for the company ‘s cost control.

• To maintain equipment in good condition.

Reliability • Reliability is defined as the probability of a plant to give

satisfactory performance in a particular period of time under specified conditions. The time between failures is called MTBF

• Availability is the percentage of time the machine will be available for operation

• Availability = Mean Time Between failures(MTBF)

MTBF + Mean Time for Repairs(MTR)

Maintenance and Reliability

The objective of maintenance and reliability is The objective of maintenance and reliability is to maintain the capability of the system while to maintain the capability of the system while controlling costscontrolling costs Maintenance is all activities involved in Maintenance is all activities involved in

keeping a system’s equipment in working keeping a system’s equipment in working orderorder

Reliability is the probability that a machine Reliability is the probability that a machine will function properly for a specified timewill function properly for a specified time

Strategic Importance of Maintenance and Reliability

Failure has far reaching effects on a firm’sFailure has far reaching effects on a firm’s OperationOperation ReputationReputation ProfitabilityProfitability Dissatisfied customersDissatisfied customers Idle employeesIdle employees Profits becoming lossesProfits becoming losses Reduced value of investment in plant and Reduced value of investment in plant and

equipmentequipment

Maintenance Strategy

Employee InvolvementEmployee Involvement

Information sharingSkill trainingReward systemEmployee empowerment

Maintenance and Reliability Maintenance and Reliability ProceduresProcedures

Clean and lubricateMonitor and adjustMake minor repairKeep computerized records

ResultsResults

Reduced inventoryImproved qualityImproved capacityReputation for qualityContinuous improvementReduced variability

Categories • Breakdown Maintenance ( Corrective maintenance)• Preventive maintenance(PM)

– Lubrication & Inspection• Predictive maintenance ( Condition monitoring)

– Is a form of PM– by tracing the performance of the machine over its

operating life, deterioration that can occur at various intervals of time is predicted. Early symptoms of failure are identified and proper maintenance measures developed.

• Routine maintenanceRoutine maintenancea. Running maintenanceb. shut down maintenance

• Planned maintenancePlanned maintenanceIt is an maintenance activities that are carried out

according to a predetermined schedule .also known as scheduled maintenance or productive maintenance.

IMPACT OF POOR MAINTENANCEIMPACT OF POOR MAINTENANCE

• Production capacity• Production costs• Product and service quality• Employee or customer safety• Customer satisfaction

IMPORTANT TACTICSIMPORTANT TACTICS

ReliabilityReliability

1.1. Improving individual componentsImproving individual components

2.2. Providing redundancyProviding redundancy MaintenanceMaintenance

1.1. Implementing or improving preventive Implementing or improving preventive maintenancemaintenance

2.2. Increasing repair capability or speedIncreasing repair capability or speed

IMPLEMENTING PREVENTIVE MAINTENANCEIMPLEMENTING PREVENTIVE MAINTENANCE

Need to know when a system requires service Need to know when a system requires service or is likely to failor is likely to fail

High initial failure rates are known as infant High initial failure rates are known as infant mortalitymortality

Once a product settles in, MTBF generally Once a product settles in, MTBF generally follows a normal distributionfollows a normal distribution

Good reporting and record keeping can aid the Good reporting and record keeping can aid the decision on when preventive maintenance decision on when preventive maintenance should be performedshould be performed

Computerized Maintenance System

Output ReportsOutput Reports

Inventory and purchasing reports

Equipment parts list

Equipment history reports

Cost analysis (Actual vs. standard)

Work orders– Preventive

maintenance– Scheduled

downtime– Emergency

maintenance

Data entry– Work requests– Purchase

requests– Time reporting– Contract work

Data FilesData Files

Personnel data with skills, wages, etc.

Equipment file with parts list

Maintenanceand work order

schedule

Inventory of spare parts

Repair history file

Maintenance Costs

The traditional view attempted to balance The traditional view attempted to balance preventive and breakdown maintenance costs preventive and breakdown maintenance costs

Typically this approach failed to consider the Typically this approach failed to consider the true total cost of breakdownstrue total cost of breakdowns InventoryInventory Employee moraleEmployee morale Schedule unreliabilitySchedule unreliability

Increasing Repair Capabilities

1.1. Well-trained personnelWell-trained personnel2.2. Adequate resourcesAdequate resources3.3. Ability to establish repair plan and prioritiesAbility to establish repair plan and priorities4.4. Ability and authority to do material planningAbility and authority to do material planning5.5. Ability to identify the cause of breakdownsAbility to identify the cause of breakdowns6.6. Ability to design ways to extend MTBFAbility to design ways to extend MTBF

How Maintenance is Performed

OperatorOperator Maintenance Maintenance departmentdepartment

Manufacturer’s Manufacturer’s field servicefield service

Depot serviceDepot service(return equipment)(return equipment)

Preventive maintenance costs less and is faster the more we move to the left

Competence is higher as we move to the right

Total Productive Maintenance (TPM)

Designing machines that are reliable, easy to Designing machines that are reliable, easy to operate, and easy to maintainoperate, and easy to maintain

Emphasizing total cost of ownership when Emphasizing total cost of ownership when purchasing machines, so that service and purchasing machines, so that service and maintenance are included in the costmaintenance are included in the cost

Developing preventive maintenance plans Developing preventive maintenance plans that utilize the best practices of operators, that utilize the best practices of operators, maintenance departments, and depot servicemaintenance departments, and depot service

Training workers to operate and maintain their Training workers to operate and maintain their own machinesown machines

Establishing Maintenance Policies

SimulationSimulation Computer analysis of complex situationsComputer analysis of complex situations Model maintenance programs before they Model maintenance programs before they

are implementedare implemented Physical models can also be usedPhysical models can also be used

Expert systemsExpert systems Computers help users identify problems Computers help users identify problems

and select course of actionand select course of action

What is system reliability?

Also known as product reliability. When components or parts are combined into a larger

system, such as a machine or a product, the combined reliability of all the components or parts form the basis for system reliability.

Knowing how to calculate system reliability

• When critical components interact during the operation of the product or system, the reliability of the product or system is determined by computing the product of the reliabilities of all the interacting critical components.

Calculation.

• If a product or system has ‘n’ critical components each with reliability CR1, CR2,….. CRN, then the product or system reliability SR= CR1*CR2*……CRN (this is known as multiplication law of probability).

• 10 critical points, each having a reliability of 0.99, the reliability of that product would be (0.99)10 = 0.904. 100 critical components, each having a reliability of 0.99, system reliability would be (0.99)100 = 0.366.

Fault tree analysis: a systematic and stylized

deductive process. An undesired event is defined. The event is resolved into its immediate causes. This resolution of events continues until basic causes are identified A logical diagram called a fault tree is constructed

showing the logical event relationships

Benefits of Constructing a Fault Tree

Explicitly shows all the different relationships that are necessary to result in the top event

A thorough understanding is obtained of the logic and basic causes leading to the top event

Is a tangible record of the systematic analysis of the logic and basic causes leading to the top event

Why FTA is carried out ?

To exhaustively identify the causes of a failure To identify weaknesses in a system To assess a proposed design for its reliability or safety To identify effects of human errors To prioritize contributors to failure To identify effective upgrades to a system To quantify the failure probability

Role of FTA in System Safety Analysis

FTA is used to resolve the causes of system failure FTA is used to quantify system failure probability FTA is used to evaluate potential upgrades to a system FTA is used to optimize resources in assuring system

safety FTA is used to resolve causes of an incident

The Thought Process in FTA

FTA is backward looking The end result is the analysis starting point The end result is then traced back one step at a time to

its immediate causes The relationships of the causes, or events, are shown

with logic symbols This backward tracing process continues until the basic

causes are identified FTA systematizes and codifies the process

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