1. McGraw-Hill/Irwin Copyright © 2009 by The McGraw-Hill Companies, Inc. All Rights Reserved. Chapter 6 Process Selection and Facilities Layout

2. 6- 2 Process Selection Process selection –Refers to the deciding on the way production of goods or services will be organized –It has major implications for Capacity planning Layout of facilities Equipment Design of work systems

3. 6- 3 Process Selection and System Design

4. 6- 4 Process Selection 1.Variety –How much? 2.Equipment flexibility –To what degree? 3.Volume –Expected output? Job ShopRepetitive Batch Continuous

5. 6- 5 Types of Processing

6. 6- 6 Product-Process Matrix

7. 6- 7 Facilities Layout Layout –the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system –Facilities layout decisions arise when: Designing new facilities Re-designing existing facilities

8. 6- 8 The Need for Layout Planning Inefficient operations –High cost –Bottlenecks Accidents or safety hazards Changes in product or service design Introduction of new products or services

9. 6- 9 The Need for Layout Planning Changes in output volume or product mix Changes in methods or equipment Changes in environmental or other legal requirements Morale problems

10. 6- 10 Layout Design Objectives Basic Objective –Facilitate a smooth flow of work, material, and information through the system Supporting objectives –Facilitate product or service quality –Use workers and space efficiently –Avoid bottlenecks –Minimize material handling costs –Eliminate unnecessary movement of workers or material –Minimize production time or customer service time –Design for safety

11. 6- 11 Basic Layout Types Product layouts Process layouts Fixed-Position layout Combination layouts

12. 6- 12 Repetitive Processing: Product Layouts Product layout – Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow Raw materials or customer Finished item Station 2 Station 2 Station 3 Station 3 Station 4 Station 4 Material and/or labor Station 1 Material and/or labor Material and/or labor Material and/or labor Used for Repetitive Processing Repetitive or Continuous

13. 6- 13 Product Layout: Advantages High rate of output Low unit cost Labor specialization Low material handling cost per unit High utilization of labor and equipment Established routing and scheduling

14. 6- 14 Product Layout: Disadvantages Creates dull, repetitive jobs Fairly inflexible to changes in volume or product or process design Highly susceptible to shutdowns Preventive maintenance, capacity for quick repair and spare-parts inventories are necessary expenses Individual incentive plans are impractical

15. 6- 15 Non-repetitive Processing: Process Layouts Process layouts –Layouts that can handle varied processing requirements Used for Intermittent processing Job Shop or Batch Dept. A Dept. BDept. D Dept. C Dept. F Dept. E

16. 6- 16 Surgery Radiology ER triage room ER BedsPharmacy Emergency room admissions Billing/exit Laboratories Process-Oriented Layout in a Hospital Patient A - broken leg Patient B -erratic heart pacemaker (Source: Heizer & Render(2008),Operations Management 8 th ed, Prentice Hall)

17. 6- 17 Process Layout: Advantages Can handle a variety of processing requirements Not particularly vulnerable to equipment failures General-purpose equipment is often less costly than the specialized equipment used in product layouts It is possible to use individual incentive plans

18. 6- 18 Process Layout: Disadvantages Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Special attention for each product or customer

19. 6- 19 Fixed Position Layouts Fixed Position layout – Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed

20. 6- 20 Combination Layouts Some operational environments use a combination of the three basic layout types: –Hospitals –Supermarket –Shipyards

21. 6- 21 Service Layout Service layouts can be categorized as: product, process, or fixed position Service layout requirements are somewhat different due to such factors as: –Degree of customer contact –Degree of customization Common service layouts: –Warehouse and storage layouts –Retail layouts –Office layouts

22. 6- 22 Line Balancing (for assembly line) Line balancing –The process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements –to minimize the imbalance between machines or personnel while meeting required output –Why is line balancing important? 1.It allows us to use labor and equipment more efficiently. 2.To avoid fairness issues that arise when one workstation must work harder than another.

23. 6- 23 Cycle Time Cycle time –The maximum time allowed at each workstation to complete its set of tasks on a unit –Cycle time also establishes the output rate of a line

24. 6- 24 Cycle Time and Output Rate

25. 6- 25 How Many Workstations are Needed? The required number of workstations is a function of –Desired output rate –Our ability to combine tasks into a workstation Theoretical minimum number of stations

26. 6- 26 Precedence Diagram Precedence diagram –A diagram that shows elemental tasks and their precedence requirements

27. 6- 27 Measuring Effectiveness Balance delay (percentage of idle time) –Percentage of idle time of a line Efficiency –Percentage of busy time of a line

28. 6- 28 Assigning Tasks to Workstations Break ties by - Assign the task with longest task time - Assign the task with the greatest no. of followers Some Heuristic (Intuitive) Rules: –Assign tasks in order of most following tasks Count the number of tasks that follow –Assign tasks in order of greatest positional weight. Positional weight is the sum of each task’s time and the times of all following tasks.

29. 6- 29 Example This means that tasks B and E cannot be done until task A has been completed PerformanceTask Must Follow TimeTask Listed Task(minutes)Below A10— B11A C5B D4B E12A F3C, D G7F H11E I3G, H Total time 66 480 mins available per day 40 units of product required

30. 6- 30 Example PerformanceTask Must Follow TimeTask Listed Task(minutes)Below A10— B11A C5B D4B E12A F3C, D G7F H11E I3G, H Total time 66 I G F C D H B E A 10 1112 5 4 3 7113 Figure 9.13

31. 6- 31 I G F C D H B E A 10 1112 5 4 3 7113 Figure 9.13 PerformanceTask Must Follow TimeTask Listed Task(minutes)Below A10— B11A C5B D4B E12A F3C, D G7F H11E I3G, H Total time 66 Example 480available mins per day 40units required Cycle time = Production time available per day Units required per day = 480 / 40 = 12 minutes per unit Theoretical Minimum number of workstations = ∑ Time for task i Cycle time n i = 1 = 66 / 12 = 5.5 or 6 stations

32. 6- 32 480available mins per day 40units required Cycle time = 12 mins Minimum workstations = 5.5 or 6 PerformanceTask Must Follow TimeTask Listed Task(minutes)Below A10— B11A C5B D4B E12A F3C, D G7F H11E I3G, H Total time 66 Example I GF H C D B E A 1011 12 5 4 37 11 3 Station 1 Station 2 Station 3 Station 5 Station 4 Station 6 Figure 9.14

33. 6- 33 PerformanceTask Must Follow TimeTask Listed Task(minutes)Below A10— B11A C5B D4B E12A F3C, D G7F H11E I3G, H Total time 66 Example 480available mins per day 40units required Cycle time = 12 mins Minimum workstations = 5.5 or 6 Efficiency = ∑ Task times (actual number of workstations) x (largest cycle time) = 66 minutes / (6 stations) x (12 minutes) = 91.7%