C11 maintenance

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Operations Operations ManagementManagement

Maintenance ManagementMaintenance ManagementChapter 11Chapter 11

Maintenance Maintenance

The objective of maintenance is to The objective of maintenance is to maintain the capability of the maintain the capability of the system while controlling costssystem while controlling 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 order or operating conditionorder or operating condition

Maintenance is concerned with avoiding Maintenance is concerned with avoiding or minimizing downtime or to avoid or minimizing downtime or to avoid undesirable results due to system failure. undesirable results due to system failure.

Concept of MaintenanceConcept of Maintenance

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The most important function of maintenance is to provide system reliability that is to ensure that a specific machine continues to function for a specified period of time with minimum chances of breaking down and at minimum costs. This can be achieved through:

increasing repair capabilities or speeding the repair activities to minimizing interruption.

implementing preventive maintenance

Strategic Importance of Strategic Importance of MaintenanceMaintenance

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Maintenance can avoid work stoppage and ensure that the lost of production time and cost are minimized.

To keep the entire production system running smoothly with minimum interruption.

To avoid loss of sales and profits Help reduce production cost such as idle labor

cost and overtime cost

Strategic Importance of Maintenance Strategic Importance of Maintenance – cont.– cont.

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To ensure that the entire workplace is a safe place to work for its employees.

To established a competitive edge and to enhance good customer service.

To ensure that the product meet the expected quality and specifications.

To reduce cost of breakdown and repairs.

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Good Maintenance StrategyGood Maintenance Strategy

Requires: Employee involvement Maintenance and reliability procedures

To yield: Reduced inventory Improved quality Improved capacity Reputation for quality Continuous improvement

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Employee InvolvementEmployee Involvement

Information sharing Skill training Reward system Power sharing

© 1995 Corel Corp.

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Lower operating

costs

Continuous improvement

Faster, more dependable throughput

Higher productivity

Improved quality

Improved capacity

Reduced inventory

Maintenance

Maintenance BenefitsMaintenance Benefits

MaintenanceMaintenance

Two types of maintenanceTwo types of maintenance

1.1. Breakdown MaintenanceBreakdown Maintenance

2.2. Preventive MaintenancePreventive Maintenance

Breakdown MaintenanceBreakdown Maintenance

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Involves performing maintenance activities after a machine breakdown or malfunction has occurred and then must be repaired on an emergency or priority basis.

Breakdown maintenance includes repairs, replacement of parts or even overhaul to ensure the machine is put back in operating condition.

Preventive Maintenance Preventive Maintenance

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Involves performing maintenance activities before the equipment fails.

Objectives are :i) To reduce frequency and severity of interruptions to production caused by machine

malfunctions. ii) To detect potential problems earlier and avoid the associate cost

Preventive Maintenance – cont.Preventive Maintenance – cont.

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Preventive Maintenance activities includes regular inspection, machine adjustments, lubrication, cleaning and parts replacement

Two type of preventive maintenancei) Routine maintenanceii) Inspection

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How much preventive & breakdown maintenance

Who performs maintenance Centralized, decentralized, operator etc. Contract or in-house

When to replace or repair How much to replace

Individual or group replacement

Spare parts inventory and standby machines.

Maintenance DecisionsMaintenance Decisions

Spare Parts Inventory and Standby Spare Parts Inventory and Standby MachinesMachines

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Firms must maintain a certain level of spare part inventory to ensure that the repairs can be done

Some companies invest in standby machines Disadvantage of standby machines is the machine

will be under utilized.

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Centralized maintenance department Does all maintenance (PM & breakdown)

Decentralized maintenance department Useful if different equipment used in different

areas of company

Contract maintenance Used if little equipment or expertise

Operator ownership approach

Organizing theOrganizing the Maintenance Function Maintenance Function

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Operator does preventive maintenance Equipment condition is their responsibility Learns equipment better Increases worker’s pride Reduces repair time & PM costs

Maintenance department is backup Handles non-routine problems Provides maintenance training Has plant-wide responsibilities

Operator-Ownership ApproachOperator-Ownership Approach

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Contract for Preventive Contract for Preventive MaintenanceMaintenance

Compute the expected number of breakdowns without the service contract

Compute the expected breakdown cost per month with no preventive maintenance contract

Compute the cost of preventive maintenance

Compare the two options

Maintenance Cost ExampleMaintenance Cost ExampleShould the firm contract for maintenance Should the firm contract for maintenance on their printers?on their printers?

Number of Number of BreakdownsBreakdowns

Number of Months Number of Months That Breakdowns That Breakdowns

OccurredOccurred

00 22

11 88

22 66

33 4

Total: Total: 2020

Average cost of breakdown = $300Average cost of breakdown = $300Use service contract - cost RM150 per month and Use service contract - cost RM150 per month and average breakdown is 1 per month. average breakdown is 1 per month.

Maintenance Cost ExampleMaintenance Cost Example

1.1. Compute the expected number of Compute the expected number of breakdownsbreakdowns

Number of Number of BreakdownBreakdown

ss

FrequencyFrequency Number of Number of BreakdownBreakdown

ss

FrequencyFrequency

00 2/20 = .12/20 = .1 22 6/20 = .36/20 = .3

11 8/20 = .48/20 = .4 33 4/20 = .24/20 = .2

∑∑ Number of Number of breakdownsbreakdowns

Expected number Expected number of breakdownsof breakdowns

Corresponding Corresponding frequencyfrequency== xx

= (0)(.1) + (1)(.4) + (2)(.3) + (3)(.2)= (0)(.1) + (1)(.4) + (2)(.3) + (3)(.2)

= 1.6 breakdowns per month= 1.6 breakdowns per month

Maintenance Cost ExampleMaintenance Cost Example

2.2. Compute the expected breakdown cost per Compute the expected breakdown cost per month with no preventive maintenancemonth with no preventive maintenance

Expected Expected breakdown costbreakdown cost

Expected number Expected number of breakdownsof breakdowns

Cost per Cost per breakdownbreakdown== xx

= (1.6)($300)= (1.6)($300)

= $480 per month= $480 per month

Maintenance Cost ExampleMaintenance Cost Example

3.3. Compute the cost of preventive Compute the cost of preventive maintenancemaintenance

Preventive Preventive maintenance costmaintenance cost

Cost of expected Cost of expected breakdowns if service breakdowns if service contract signedcontract signed

Cost of Cost of service contractservice contract

==

++

= (1 breakdown/month)($300) + $150/month= (1 breakdown/month)($300) + $150/month= $450 per month= $450 per month

Hire the service firm; it is less expensiveHire the service firm; it is less expensive

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Tactics for MaintenanceTactics for Maintenance

Maintenance Tactics implementing preventive maintenance increasing repair capabilities

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Increasing Repair Capabilities:Features Increasing Repair Capabilities:Features of A Good Maintenance Facilityof A Good Maintenance Facility

Well-trained personnel Adequate resources Ability to establish a repair plan and

priorities Ability and authority to do material

planning Ability to identify the cause of

breakdowns Ability to design ways to extend MTBF

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Total Productive Maintenance Total Productive Maintenance (TPM)(TPM)

Additional requirements of: Designing machines that are reliable, easy to

operate and easy to maintain Emphasizing total cost of ownership when

purchasing machines, so that service and maintenance are included in the cost

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

Training workers to operate and maintain their own machines

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Techniques for Establishing Techniques for Establishing Maintenance PoliciesMaintenance Policies

Simulation - enables one to evaluate the impact of various maintenance policies

Expert systems - can be used by staff to help diagnose faults in machinery and equipment