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Chapter 6

Chapter 6. Process Selection and Facility Layout. Learning Objectives. You should be able to: Explain the strategic importance of process selection Describe the influence that process selection has on the organization Compare the basic processing types

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Chapter 6

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  1. Chapter 6 Process Selection and Facility Layout

  2. Learning Objectives • You should be able to: • Explain the strategic importance of process selection • Describe the influence that process selection has on the organization • Compare the basic processing types • Describe the basic layout types, and the main advantages and disadvantages of each • Solve simple line-balancing problems • Develop simple process layouts Instructor Slides

  3. Process Selection

  4. Process Selection • Process selection • Deciding on the way production of goods or services will be organized • Occurs when: • Planning of new products or services • Technological changes in product or equipment • Competitive pressure 6-4

  5. Process Selection Process choice is demand driven: • Variety • How much? • Equipment flexibility • To what degree? • Volume • Expected output? 6-5

  6. Process Selection • Goal: • Have process capabilities match product/service requirements. • Major implications: • Capacity planning • Layout of facilities • Equipment • Design of work systems 6-6

  7. Facilities andEquipment CapacityPlanning Forecasting Layout Product andService Design ProcessSelection WorkDesign TechnologicalChange Process Selection and System Design 6-7

  8. Process Types • Job shop • Small scale, intermittent • e.g., doctor, tailor, veterinarian • Batch • Moderate volume • e.g., bakery, cinema, airline • Repetitive/assembly line • High volumes of standardized goods or services • e.g., automobiles • Continuous • Very high volumes of non-discrete goods • e.g., petroleum products, steel, sugar, salt, electricity, Internet • Project (leave it to later chapter) • Non-routine, with a unique set of objectives to be accomplished in a limited time frame • e.g., consulting, launching a new product, publishing a book, building a bridge

  9. Types of Processing • Goal: • Have process capabilities match product/service requirements. 6-9

  10. Product-Process Matrix Variety Volume • The diagonal represents the “ideal” match • Hybrid process are possible (e.g., job-shop & batch) • Process choice may change as products goes through its life-cycles 6-10

  11. Process Choice Effects 6-11

  12. Product and Service Profiling • Product or service profiling • Linking key product or service requirements to process capabilities • Key dimensions relate to • Range of products or services that will be processed • Expected order sizes • Pricing strategies • Expected frequency of schedule changes • Order-winning requirements 6-12

  13. Product and Service Profiling

  14. Facilities Layout

  15. 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 6-15

  16. 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 • Changes in output volume or product mix • Changes in methods or equipment • Changes in environmental or other legal requirements • Morale problems 6-16

  17. 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 • Safety 6-17

  18. Importance of Layout Decisions • Requires substantial investments of money and effort • Involves long-term commitments • Has significant impact on cost and efficiency of short-term operations

  19. Basic Layout Types • 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 • Combination layouts

  20. Repetitive Processing: Product Layout (repetitive and continuous processes)

  21. Product Layouts • Product layout • Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow • http://www.youtube.com/watch?v=uVoQJrz0sH8 Raw materials or customer Station 2 Station 3 Station 4 Finished item Station 1 Material and/or labor Material and/or labor Material and/or labor Material and/or labor Used for Repetitive Processing Repetitive or Continuous 6-21

  22. 1 2 3 4 In 5 Workers 6 Out 10 9 8 7 A U-Shaped Production Line

  23. Bottleneck Operation An operation in a sequence of operations whose capacity is lower than that of the other operations Bottleneck 10/hr (6 min/unit) Operation 120/hr (3 min/unit) Operation 210/hr (6 min/unit) Operation 315/hr (4 min/unit) Maximum output ratelimited by bottleneck 5-23

  24. Line Balancing • Line balancing • The process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements • Goal: • Obtain task grouping that represent approximately equal time requirements: • minimizes idle time along the line • results in a high utilization of equipment and labor • Input • Tasks sequencing (precedence diagram) • Tasks time • Operating time 6-24

  25. Real-World Case Instructor Slides

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

  27. Cycle Time • Cycle time • The maximum time allowed at each workstation to complete its set of tasks on a unit • Minimum Cycle Time = longest task time = 1.0 min • Maximum Cycle Time = Σt = sum of task time = 2.5 min 6-27

  28. Desired Output Rate • Establishing the desired output rate of a line: 6-28

  29. How Many Workstations are Needed? • The required number of workstations is a function of: • Desired output rate • The ability to combine tasks into a workstation • (theoretical) Minimum number of stations 6-29

  30. Assigning Tasks to Workstations • 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. 6-30

  31. Example 1: Assembly Line Balancing • Arrange tasks shown the figure into workstations. - Assign tasks in order of the most number of followers

  32. Determine the Minimum Number of Workstations Required Assume: OT (Operations Time per Day)=8 hours=8*60=480 minutes D (Desired output rate)=480 units CT (Cycle Time)=OT/D=480/480=1.0 minutes per unit

  33. Example 1 Solution Assign tasks in order of the most number of followers

  34. Example 1 Solution Assign tasks in order of the most number of followers

  35. Example 1 Solution

  36. Example 1 Solution

  37. Example 1 Solution

  38. Example 1 Solution

  39. Example 1 Solution

  40. Example 1 Solution

  41. Example 1 Solution

  42. Example 1 Solution

  43. Example 1 Solution Idle time per cycle=0.5

  44. Example - Layout a & c (0.1+0.7) b (1.0) d & e (0.5+0.2)

  45. Measuring Effectiveness • Balance delay (percentage of idle time) • Percentage of idle time of a line • Efficiency • Percentage of busy time of a line 6-45

  46. Example - Measuring Effectiveness Efficiency = (1– 0.167)x100=83.3% 6-46

  47. Product Layouts 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 • Routine accounting, purchasing, and inventory control Disadvantages • Creates dull, repetitive jobs • Poorly skilled workers may not maintain equipment or quality of output • 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 6-47

  48. Non-repetitive Processing: Process Layout (Job Shop and Batch Processes)

  49. Process Layouts • Process layouts (Non-repetitive Processing) • Layouts that can handle varied processing requirements Dept. A Dept. C Dept. E Dept. B Dept. D Dept. F Used for Intermittent processing Job Shop or Batch 6-49

  50. Information Requirements • In designing process layouts, the following information is required: • A list of departments to be arranged and their dimensions • A projection of future work flows between the pairs of work centers • The distance between locations and the cost per unit of distance to move loads between them • The amount of money to be invested in the layout • A list of any special considerations • The location of key utilities, access and exit points, etc. 6-50

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