运筹学课程课件

Chapter 6
Managing Capacity
Chapter Objectives
Be able to:
▪Explain what capacity is, how firms measure capacity, and the difference between theoretical and rated capacity. ▪Describe the pros and cons associated with three different capacity strategies: lead, lag, and match. ▪Apply a wide variety of analytical tools for choosing between capacity alternatives, including expected value and break-even analysis, decision trees, and learning curves. ▪Apply the Theory of Constraints, waiting line theory, and Little’s Law to analyze and understand capacity issues in a business process environment.
Copyright © 2016 Pearson Education, Inc.
6-3
Capacity
▪ Measures of Capacity
▪ Theoretical capacity – The maximum output capability, allowing for no adjustments for preventive maintenance, unplanned downtime, or the like.
Copyright © 2016 Pearson Education, Inc.
6-6
Three Common Capacity Strategies
▪ Lead capacity strategy – A capacity strategy in which capacity is added in anticipation of demand.
6-14
Methods of Evaluating Capacity Alternatives
▪ Other Considerations:
▪ The strategic importance of an activity to a firm.
▪ The desired degree of managerial control.
▪ For every doubling of cumulative output, there is a set percentage reduction in the amount of inputs required.
Copyright © 2016 Pearson Education, Inc.
▪ Variable costs – Expenses directly tied to the level of business activity.
TC = FC + VC * X
TC = Total Cost FC = Fixed Cost VC = Variable cost per unit of business activity X = amount of business activity
6-8
Methods of Evaluating Capacity Alternatives
▪ Cost ▪ Demand Considerations ▪ Expected Value ▪ Decision Trees ▪ Break-Even Analysis ▪ Learning Curves
• Number of lines used • Number of shifts operating • Number of temporary workers used • Number of public storage facilities used • Product variations on line • Conformance quality • Quality improvement
▪ Lag capacity strategy – A capacity strategy in which capacity is added only after demand has materialized.
▪ Match capacity strategy – A capacity strategy that strikes a balance between the lead and lag capacity strategies by avoiding periods of high under or overutilization.
Copyright © 2016 Pearson Education, Inc.
6-10
Methods of Evaluating Capacity Alternatives
▪ Expected value – A calculation that summarizes the expected costs, revenues, or profits of a capacity alternative, based on several demand levels, each of which has a different probability.
Copyright © 2016 Pearson Education, Inc.
6-13
Methods of Evaluating Capacity Alternatives
▪ Learning curve theory – A body of theory based on applied statistics which suggests that productivity levels can improve at a predictable rate as people and even systems “learn” to do tasks more efficiently.
▪ Capacity decisions that managers face:
© 2013 APICS Dictionary
▪ How capacity is measured?
▪ Which factors affect capacity?
▪ The impact of the supply chain on the organization’s effective capacity.
▪ Rated capacity – The long-term, expected output capability of a resource or
system.
© 2013 APICS Dictionary
Copyright © 2016 Pearson Education, Inc.
6-4
▪ The need for flexibility.
Copyright © 2016 Pearson Education, Inc.
6-15
Understanding and Analyzing Process Capacity
▪ Theory of Constraints – An approach to visualizing and managing capacity which recognizes that nearly all products and services are created through a series of linked processes, and in every case, there is at least one process step that limits throughput for the entire chain.
Copyright © 2016 Pearson Education, Inc.
6-11
Methods of Evaluating Capacity Alternatives
▪ Decision tree – A visual tool that decision makers use to evaluate capacity decisions and to enable users to see the interrelationships between decisions and possible outcomes.
6-12
Methods of Evaluating Capacity Alternatives
▪ Break-even analysis
▪ Break-even point – The volume level for a business at which total revenues cover total costs.
Capacity
Examples of Capacity in Different Organizations
Table 6.1
Copyright © 2016 Pearson Education, Inc.
6-5
Capacity
▪ Factors that Affect Capacity
▪ Many factors affect capacity and many assumptions must be made:
Copyright © 2016 Pearson Education, Inc.