tailieunhanh - Lecture Operations management (11/e): Chapter 7S - William J. Stevenson

Supplement to Chapter 7 entitled 'Learning curves' deals with concepts of learning curves highlighting relationship between illustrate the basic relationship between increasing repetitions and decreasing time per repetition. This relationship is also referred to as an experience curve, a progress function, or an improvement function. | Learning Curves McGraw-Hill/Irwin Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved. You should be able to: Explain the concept of a learning curve Make time estimates based on learning curves List and briefly describe some of the main applications of learning curves Outline some of the cautions and criticisms of learning curves Estimate learning rates from data on job times 7S- Student Slides Learning curve The time required to perform a task decreases with increasing repetitions The degree of improvement is a function of the task being done Short, routine tasks will show modest improvement relatively quickly Longer, more complex tasks will show improvement over a longer interval 7S- Student Slides The learning effect is attributed to a variety of factors: Worker learning Preproduction factors Tooling and equipment selection Product design Methods analysis Effort expended prior to the start of work Changes made after production has begun Changes in . | Learning Curves McGraw-Hill/Irwin Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved. You should be able to: Explain the concept of a learning curve Make time estimates based on learning curves List and briefly describe some of the main applications of learning curves Outline some of the cautions and criticisms of learning curves Estimate learning rates from data on job times 7S- Student Slides Learning curve The time required to perform a task decreases with increasing repetitions The degree of improvement is a function of the task being done Short, routine tasks will show modest improvement relatively quickly Longer, more complex tasks will show improvement over a longer interval 7S- Student Slides The learning effect is attributed to a variety of factors: Worker learning Preproduction factors Tooling and equipment selection Product design Methods analysis Effort expended prior to the start of work Changes made after production has begun Changes in work methods Changes in tooling and equipment Managerial factors Improvements in planning, scheduling, motivation, and control 7S- Student Slides The learning effect is predictable The learning percentage is constant Every doubling of repetitions results in a constant percentage decrease in the time per repetition Typical decreases range from 10 to 20 percent 7S- Student Slides Each time cumulative output doubles, the time per unit for that amount should be approximately equal to the previous time multiplied by the learning percentage. If the first unit of a process took 100 hours and the learning rate is 90%: Unit Unit Time (hours) 1 = 100 2 .90(100) = 90 4 .90(90) = 81 8 .90(81) = 16 .90() = 32 .90() = 7S- Student Slides 7S- Student Slides If the learning rate is 90, and the first unit took 100 hours to complete, how long would it take to complete the 25th unit? 7S- Student Slides The learning factor approach uses a table that shows two .