Operations management by stevenson 9th ch15s

15S Maintenance McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc All Learning Objectives  Explain the importance of maintenance in production systems  Describe the range of maintenance activities  Discuss preventative maintenance and the key issues associated with it  Discuss breakdown maintenance and the key issues associated with it  State how the Pareto phenomenon pertains to maintenance decisions 15S-2 Introduction  Maintenance  All activities that maintain facilities and equipment in good working order so that a system can perform as intended  Two basic categories  Building and grounds  Equipment maintenance 15S-3 Goal of Maintenance  To keep production systems in good working order at minimal cost  Reasons for maintenance     To avoid production or service disruptions To not add production or service costs To maintain high quality To avoid missed delivery dates 15S-4 Breakdown Consequences     Operations capacity reduced No output, but overhead continues Quality issues – output may be damaged Safety issues – employees or customers may be injured 15S-5 Reactive vs Proactive Reactive Maintenance:  Breakdown maintenance  Reactive approach; dealing with breakdowns or problems when they occur Proactive Maintenance:  Preventive maintenance  Proactive approach; reducing breakdowns through a program of lubrication, adjustment, cleaning, inspection, and replacement of worn parts 15S-6 Maintenance Reasons  Reasons for keeping equipment running     Avoid production disruptions Not add to production costs Maintain high quality Avoid missed delivery dates 15S-7 Breakdown Consequences  Production capacity is reduced  Orders are delayed  No production  Overhead continues  Cost per unit increases  Quality issues  Product may be damaged  Safety issues  Injury to employees  Injury to customers 15S-8 Total Maintenance Cost Table 14S.1 Cost Total Cost Preventive maintenance cost Breakdown and repair cost Optimum Amount of preventive maintenance 15S-9 Preventive Maintenance  Preventive maintenance: goal is to reduce the incidence of breakdowns or failures in the plant or equipment to avoid the associated costs  Preventive maintenance is periodic  Result of planned inspections  According to calendar  After predetermined number of hours 15S-10 Example S-1 Frequency of breakdown Number of breakdowns Frequency of occurrence 20 30 40 10 If the average cost of a breakdown is $1,000, and the cost of preventative maintenance is $1,250 per month, should we use preventive maintenance? 15S-11 Example S-1 Solution Number of Breakdowns Frequency of Occurrence 20 30 40 10 1.00 Expected number of Breakdowns 30 80 30 1.40 Expected cost to repair = 1.4 breakdowns per month X $1000 = $1400 Preventive maintenance = $1250 PM results in savings of $150 per month 15S-12 Predictive Maintenance  Predictive maintenance  An attempt to determine when best to perform preventive maintenance activities  Total productive maintenance  JIT approach where workers perform preventive maintenance on the machines they operate 15S-13 Breakdown Programs  Standby or backup equipment that can be quickly pressed into service  Inventories of spare parts that can be installed as needed  Operators who are able to perform minor repairs  Repair people who are well trained and readily available to diagnose and correct problems with equipment 15S-14 Replacement  Trade-off decisions  Cost of replacement vs cost of continued maintenance  New equipment with new features vs maintenance  Installation of new equipment may cause disruptions  Training costs of employees on new equipment  Forecasts for demand on equipment may require new equipment capacity  When is it time for replacement? 15S-15 ... costs To maintain high quality To avoid missed delivery dates 15S-4 Breakdown Consequences     Operations capacity reduced No output, but overhead continues Quality issues – output may be damaged... workers perform preventive maintenance on the machines they operate 15S-13 Breakdown Programs  Standby or backup equipment that can be quickly pressed into service  Inventories of spare parts that