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- 1. 6-1 Process Selection and Facility Layout William J. Stevenson Operations Management 8th edition
- 2. 6-2 Process Selection and Facility Layout CHAPTER 6 Process Selection and Facility Layout McGraw-Hill/Irwin Operations Management, Eighth Edition, by William J. Stevenson Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.
- 3. 6-3 Process Selection and Facility Layout Process selection Deciding on the way production of goods or services will be organized Major implications Capacity planning Layout of facilities Equipment Design of work systems Introduction
- 4. 6-4 Process Selection and Facility Layout Forecasting Product and Service Design Technological Change Capacity Planning Process Selection Facilities and Equipment Layout Work Design Figure 6.1 Process Selection and System Design
- 5. 6-5 Process Selection and Facility Layout • Key aspects of process strategy – Capital intensive – equipment/labor – Process flexibility – Adjust to changes – Design – Volume – technology Process Strategy
- 6. 6-6 Process Selection and Facility Layout Variety How much Flexibility What degree Volume Expected output Job Shop Batch Repetitive Continuous Process Selection
- 7. 6-7 Process Selection and Facility Layout Job shop Small scale Batch Moderate volume Repetitive/assembly line High volumes of standardized goods or services Continuous Very high volumes of non-discrete goods Process Types
- 8. 6-8 Process Selection and Facility Layout Process Type Job Shop Appliance repair Emergency room Not feasible Batch Commercial bakery Classroom Lecture Repetitive Automotive assembly Automatic carwash Continuous (flow) Not feasible Oil refinery Water purification Figure 6.2 Product – Process Matrix
- 9. 6-9 Process Selection and Facility Layout Dimension Job variety Very High Moderate Low Very low Process flexibility Very High Moderate Low Very low Unit cost Very High Moderate Low Very low Volume of output Very High Low High Very low Figure 6.2 (cont’d) Product – Process Matrix
- 10. 6-10 Process Selection and Facility Layout Automation: Machinery that has sensing and control devices that enables it to operate Fixed automation Programmable automation Automation
- 11. 6-11 Process Selection and Facility Layout • Computer-aided design and manufacturing systems (CAD/CAM) • Numerically controlled (NC) machines • Robot • Manufacturing cell • Flexible manufacturing systems(FMS) • Computer-integrated manufacturing (CIM) Automation
- 12. 6-12 Process Selection and Facility 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
- 13. 6-13 Process Selection and Facility Layout Requires substantial investments of money and effort Involves long-term commitments Has significant impact on cost and efficiency of short-term operations Importance of Layout Decisions
- 14. 6-14 Process Selection and Facility Layout Inefficient operations For Example: High Cost Bottlenecks Changes in the design of products or services The introduction of new products or services Accidents Safety hazards The Need for Layout Decisions
- 15. 6-15 Process Selection and Facility Layout Changes in environmental or other legal requirements Changes in volume of output or mix of products Changes in methods and equipment Morale problems The Need for Layout Design (Cont’d)
- 16. 6-16 Process Selection and Facility Layout Product layouts Process layouts Fixed-Position layout Combination layouts Basic Layout Types
- 17. 6-17 Process Selection and Facility Layout Product layout Layout that uses standardized processing operations to achieve smooth, rapid, high- volume flow Process layout Layout that can handle varied processing requirements Fixed Position layout Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed Basic Layout Types
- 18. 6-18 Process Selection and Facility Layout Raw materials or customer Finished item Station 2 Station 3 Station 4 Material and/or labor Station 1 Material and/or labor Material and/or labor Material and/or labor Used for Repetitive or Continuous Processing Figure 6.4 Product Layout
- 19. 6-19 Process Selection and Facility Layout High rate of output Low unit cost Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling Routing accounting and purchasing Advantages of Product Layout
- 20. 6-20 Process Selection and Facility Layout Creates dull, repetitive jobs Poorly skilled workers may not maintain equipment or quality of output Fairly inflexible to changes in volume Highly susceptible to shutdowns Needs preventive maintenance Individual incentive plans are impractical Disadvantages of Product Layout
- 21. 6-21 Process Selection and Facility Layout 1 2 3 4 5 6 7 8 9 10 In Out Workers Figure 6.6 A U-Shaped Production Line
- 22. 6-22 Process Selection and Facility Layout Dept. A Dept. B Dept. D Dept. C Dept. F Dept. E Used for Intermittent processing Job Shop or Batch Process Layout (functional) Figure 6.7 Process Layout
- 23. 6-23 Process Selection and Facility Layout Work Station 1 Work Station 2 Work Station 3 Figure 6.7 (cont’d) Product Layout (sequential) Used for Repetitive Processing Repetitive or Continuous Product Layout
- 24. 6-24 Process Selection and Facility Layout Can handle a variety of processing requirements Not particularly vulnerable to equipment failures Equipment used is less costly Possible to use individual incentive plans Advantages of Process Layouts
- 25. 6-25 Process Selection and Facility Layout In-process inventory costs can be high Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Complexities often reduce span of supervision Special attention for each product or customer Accounting and purchasing are more involved Disadvantages of Process Layouts
- 26. 6-26 Process Selection and Facility Layout Cellular Production Layout in which machines are grouped into a cell that can process items that have similar processing requirements Group Technology The grouping into part families of items with similar design or manufacturing characteristics Cellular Layouts
- 27. 6-27 Process Selection and Facility Layout Dimension Functional Cellular Number of moves between departments many few Travel distances longer shorter Travel paths variable fixed Job waiting times greater shorter Throughput time higher lower Amount of work in process higher lower Supervision difficulty higher lower Scheduling complexity higher lower Equipment utilization lower higher Table 6.3 Functional vs. Cellular Layouts
- 28. 6-28 Process Selection and Facility Layout Warehouse and storage layouts Retail layouts Office layouts Other Service Layouts
- 29. 6-29 Process Selection and Facility Layout Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements. Design Product Layouts: Line Balancing
- 30. 6-30 Process Selection and Facility Layout Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit. Cycle Time
- 31. 6-31 Process Selection and Facility Layout Output capacity = OT CT OT operating time per day D = Desired output rate CT = cycle time = OT D Determine Maximum Output
- 32. 6-32 Process Selection and Facility Layout N = (D)( t) OT t = sum of task times Determine the Minimum Number of Workstations Required
- 33. 6-33 Process Selection and Facility Layout Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements A Simple Precedence Diagram a b c d e 0.1 min. 0.7 min. 1.0 min. 0.5 min. 0.2 min. Figure 6.10 Precedence Diagram
- 34. 6-34 Process Selection and Facility Layout Arrange tasks shown in Figure 6.10 into three workstations. Use a cycle time of 1.0 minute Assign tasks in order of the most number of followers Example 1: Assembly Line Balancing
- 35. 6-35 Process Selection and Facility Layout Workstation Time Remaining Eligible Assign Task Revised Time Remaining Station Idle Time 1 1.0 0.9 0.2 a, c c none a c - 0.9 0.2 0.2 2 1.0 b b 0.0 0.0 3 1.0 0.5 0.3 d e - d e - 0.5 0.3 0.3 0.5 Example 1 Solution
- 36. 6-36 Process Selection and Facility Layout Percent idle time = Idle time per cycle (N)(CT) Efficiency = 1 – Percent idle time Calculate Percent Idle Time
- 37. 6-37 Process Selection and Facility Layout 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. Some Heuristic (intuitive) Rules: Line Balancing Rules
- 38. 6-38 Process Selection and Facility Layout c d a b e f g h 0.2 0.2 0.3 0.8 0.6 1.0 0.4 0.3 Example 2
- 39. 6-39 Process Selection and Facility Layout Station 1 Station 2 Station 3 Station 4 a b e f d g h c Solution to Example 2
- 40. 6-40 Process Selection and Facility Layout 1 min. 2 min. 1 min. 1 min. 30/hr. 30/hr. 30/hr. 30/hr. 1 min. 1 min. 1 min. 1 min. 60/hr. 30/hr. 30/hr. 60/hr. 1 min. 30/hr. 30/hr. Bottleneck Parallel Workstations Parallel Workstations
- 41. 6-41 Process Selection and Facility Layout Information Requirements: 1. List of departments 2. Projection of work flows 3. Distance between locations 4. Amount of money to be invested 5. List of special considerations 6. Location of key utilities Designing Process Layouts
- 42. 6-42 Process Selection and Facility Layout 1 3 2 30 170 10 0 A B C Figure 6.12 Example 3: Interdepartmental Work Flows for Assigned Departments
- 43. 6-43 Process Selection and Facility Layout Author’s note: The following three slides are not in the 8e, but I like to use them for alternate examples.
- 44. 6-44 Process Selection and Facility Layout Process Layout - work travels to dedicated process centers Milling Assembly & Test Grinding Drilling Plating Process Layout
- 45. 6-45 Process Selection and Facility Layout Gear cutting Mill Drill Lathes Grind Heat treat Assembly 111 333 222 444 222 111 444 111 333 1111 2222 222 3333 111 444 111 Functional Layout
- 46. 6-46 Process Selection and Facility Layout -1111 -1111 222222222 - 2222 Assembly 3333333333 - 3333 44444444444444 - 4444 Lathe Lathe Mill Mill Mill Mill Drill Drill Drill Heat treat Heat treat Heat treat Gear cut Gear cut Grind Grind Cellular Manufacturing Layout