PRODUCTION SYSTEMS AND OPERATIONS MANAGEMENT

©1998 Joseph Martinich. All rights reserved. None of these materials can be stored, transmitted or reproduced by any means (electronic, mechanical, photocopying or otherwise) without the written permission of Joseph Martinich. These materials may be used by students in classes taught by Professor Martinich at University of Missouri - St. Louis.


Process Selection



Classification of Production Process Structures

1. Flow Processes

2. Job-Shop Processes

3. Cellular Processes

4. Project Processes


Flow Processes





Continuous Flow Repetitive Flow Batch Flow
Few Products Few Products Moderate # Products
Large Volume Large Volume Moderate Volume
Little/no Flexibility Little/no Flexibility Moderate Flexibility


Advantages/Benefits

1. Specialization of Equipment

2. Specialization of Labor

3. Simple Product Flow and Material Handling

4. Work-in-Process Inventories are Small


5. Space Utilization is Efficient

6. Easier to Achieve Quality Conformance

7. Production Scheduling and Coordinating is Easier

8. Easier to Monitor Costs


Disadvantages

1. Little Production Flexibility

2. Large Initial Cost

3. Worker Dissatisfaction


4. System Vulnerability


Job-Shop Processes


Advantages/Benefits

1. Flexibility

2. Low initial cost

3. Work is more diverse and interesting

4. Less vulnerable


Disadvantages

1. General purpose equipment is less efficient

2. Greater employee skill needed

3. Less efficient (but more flexible) material handling

4. Large in-process inventories

5. Large space requirements

6. Quality conformance is difficult

7. Difficult to schedule

8. Difficult to assign costs to products accurately


Hybrid or Cellular Processes


Advantages Relative to Job-Shop Process

Reported benefits from 32 companies implementing Cellular Manufacturing

Benefit Mean Percentage Improvement

Reduction in material handling 39.3

Reduction in set-up time 32.0

Reduction in throughput time 45.6

Reduction in work-in-process inventories 41.4

Reduction in finished inventories 29.2

Reduction in space needs 31.0

Increase in equipment utilization 23.3

Reduction in number of fixtures 33.1

Reduction in pieces of equipment

required to manufacture cell 19.5

parts

Reduction in labor cost 26.2

Improvement in labor satisfaction 34.4

Improvement in part quality 29.6

From "Cellular Manufacturing in the U.S. Industry:A Survey of Users," by Urban Wemmerlov and Nancy L. Hyer, International Journal of Production Research, 27, 1989, pp. 1511-1530.


Disadvantages


Project Processes


Modern Production Technologies

1. Group Technology

2. Process Automation

3. Information Systems


Selecting and Evaluating Production Processes and Technology

1. Product/Process Matrix

2. Cross-Over Analysis

3. Present-Value Analysis

4. Multi-dimensional Scoring (Decision Analysis)


Product/Process Matrix




Cross-Over Analysis


$5 x = $7,500,000 => x = 1,500,000

$4 x = $12,000,000 => x = 3,000,000


Present Value (Time Value of Money)


Multi-dimensional Utility (Scoring)


URL: http://www.umsl.edu/~jmartini/pomnotes/webprocessstruct.htm
Page Owner: Joseph Martinich (Joseph.Martinich@umsl.edu)
Last Modified: September 25, 1998