6 Process Selection and Facility Layout McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved. Learning Objectives Explain the strategic importance of process selection. Explain the influence that process selection has on an organization. Describe the basic processing types. Discuss automated approaches to processing. Explain the need for management of technology. 6-2 Learning Objectives List some reasons for redesign of layouts. Describe the basic layout types. List the main advantages and disadvantages of product layouts and process layouts. Solve simple line-balancing problems. Develop simple process layouts. 6-3 Introduction 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 6-4 Figure 6.1 Process Selection and System Design Forecasting Capacity Planning Product and Service Design Technological Change Facilities and Equipment Layout Process Selection Work Design 6-5 Process Strategy • Key aspects of process strategy – Capital intensive – equipment/labor – Process flexibility – Technology – Adjust to changes – Design – Volume – technology 6-6 Technology Technology: The application of scientific discoveries to the development and improvement of products and services and operations processes. Technology innovation: The discovery and development of new or improved products, services, or processes for producing or providing them. 6-7 Kinds of Technology Operations management is primarily concerned with three kinds of technology: Product and service technology Process technology Information technology All three have a major impact on: Costs Productivity Competitiveness 6-8 Technology Competitive Advantage Innovations in Products and services Cell phones PDAs Wireless computing Processing technology Increasing productivity Increasing quality Lowering costs 6-9 Technology Acquisition Technology can have benefits but … Technology risks include: What technology will and will not do Technical issues Economic issues Initial costs, space, cash flow, maintenance Consultants and/or skilled employees Integration cost, time resources Training, safety, job loss 6-10 Process Selection Variety Batch How much Flexibility What degree Job Shop Repetitive Volume Expected output Continuous 6-11 Process Types 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 6-12 Figure 6.2 Product and Service Processes Process Type Job Shop Appliance repair Emergency room Ineffective Commercial baking Batch Classroom Lecture Automotive assembly Repetitive Automatic carwash Continuous (flow) Ineffective Steel Production Water purification 6-13 Product – Process Matrix Figure 6.2 (cont’d) 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 6-14 Product and Process Profiling Process selection can involve substantial investment in Equipment Layout of facilities Product profiling: Linking key product or service requirements to process capabilities Key dimensions Range of products or services Expected order sizes Pricing strategies Expected schedule changes Order winning requirements 6-15 Automation Automation: Machinery that has sensing and control devices that enables it to operate Fixed automation Programmable automation 6-16 Automation • Computer-aided design and manufacturing systems (CAD/CAM) • Numerically controlled (NC) machines • Robot • Manufacturing cell • Flexible manufacturing systems(FMS) • Computer-integrated manufacturing (CIM) 6-17 Facilities Layout Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system Product layouts Process layouts Fixed-Position layout Combination layouts 6-18 Objective of Layout Design 1. Facilitate attainment of product or service quality 2. Use workers and space efficiently 3. Avoid bottlenecks 4. Minimize unnecessary material handling costs 5. Eliminate unnecessary movement of workers or materials 6. Minimize production time or customer service time 7. Design for safety 6-19 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 6-20 The Need for Layout Decisions Inefficient operations For Example: High Cost Bottlenecks Changes in the design of products or services Accidents The introduction of new products or services Safety hazards 6-21 The Need for Layout Design (Cont’d) Changes in environmental or other legal requirements Changes in volume of output or mix of products Morale problems Changes in methods and equipment 6-22 Basic Layout Types Product layouts Process layouts Fixed-Position layout Combination layouts 6-23 Basic Layout Types Product layout Layout that uses standardized processing operations to achieve smooth, rapid, highvolume 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 6-24 Product Layout Figure 6.4 Raw materials or customer Material and/or labor Station 1 Material and/or labor Station 2 Material and/or labor Station 3 Station 4 Finished item Material and/or labor Used for Repetitive or Continuous Processing 6-25 Advantages of Product 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 6-26 Disadvantages of Product 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 6-27 A U-Shaped Production Line Figure 6.6 In 1 2 3 4 5 Workers 6 Out 10 9 8 7 6-28 Process Layout Figure 6.7 Process Layout (functional) Dept. A Dept. C Dept. E Dept. B Dept. D Dept. F Used for Intermittent processing Job Shop or Batch Processes 6-29 Product Layout Figure 6.7 (cont’d) Product Layout (sequential) Work Station 1 Work Station 2 Work Station 3 Used for Repetitive Processing Repetitive or Continuous Processes 6-30 Advantages of Process Layouts Can handle a variety of processing requirements Not particularly vulnerable to equipment failures Equipment used is less costly Possible to use individual incentive plans 6-31 Disadvantages of Process Layouts 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 6-32 Fixed Position Layouts Fixed Position Layout: Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed. Nature of the product dictates this type of layout Weight Size Bulk Large construction projects 6-33 Cellular Layouts 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 6-34 Functional vs. Cellular Layouts Table 6.3 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 6-35 Service Layouts Warehouse and storage layouts Retail layouts Office layouts Service layouts must be aesthetically pleasing as well as functional 6-36 Design Product Layouts: Line Balancing Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements. 6-37 Cycle Time Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit. 6-38 Determine Maximum Output OT Output rate = CT OT operating time per day D = Desired output rate OT CT = cycle time = D 6-39 Determine the Minimum Number of Workstations Required N= ( t) CT t = sum of task time 6-40 Precedence Diagram Figure 6.11 Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements 0.1 min. 1.0 min. a b c 0.7 min. d 0.5 min. A Simple Precedence Diagram e 0.2 min. 6-41 Example 1: Assembly Line Balancing 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 6-42 Example 1 Solution Eligible Revised Assign Time Task Remaining 1.0 0.9 0.2 a, c c none a c - 0.9 0.2 2 1.0 b b 0.0 3 1.0 0.5 0.3 d e - d e - 0.5 0.3 Time Workstation Remaining 1 Station Idle Time 0.2 0.0 0.3 0.5 6-43 Calculate Percent Idle Time Idle time per cycle Percent idle time = (N)(CT) Efficiency = 1 – Percent idle time 6-44 Line Balancing Rules 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. 6-45 Example 2 0.2 0.2 0.3 a b e 0.8 0.6 c d f g h 1.0 0.4 0.3 6-46 Solution to Example 2 Station 1 a b Station 2 Station 3 e f c Station 4 g h d 6-47 Bottleneck Workstation 1 min. 30/hr. 1 min. 30/hr. 2 min. 30/hr. 1 min. 30/hr. Bottleneck 6-48 Parallel Workstations 30/hr. 1 min. 60/hr. 2 min. 30/hr. 1 min. 1 min. 60/hr. 30/hr. 2 min. 30/hr. Parallel Workstations 6-49 Designing Process Layouts 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 6-50 Example 3: Interdepartmental Work Flows Figure 6.13 for Assigned Departments 30 1 A 170 B 3 10 0 2 C 6-51 PowerPoint Author’s note: The following three slides are not in the 9e text, but I like to use them for alternate examples. 6-52 Process Layout Milling Assembly & Test Grinding Drilling Plating Process Layout - work travels to dedicated process centers 6-53 Functional Layout 222 444 Mill 111 333 111 333 Lathes 222 111 444 222 Drill Grind 3333 1111 2222 Heat treat Assembly 111 Gear cutting 111 444 6-54 -1111 Lathe Mill Drill 222222222 Mill 3333333333 Lathe Mill 44444444444444 Drill Mill Heat treat Gear -1111 cut Heat treat Grind - 2222 Heat treat Grind - 3333 Drill Gear - 4444 cut Assembly Cellular Manufacturing Layout 6-55 Video: Process Design 6-56 Video: Process Implementation 6-57 Video: Process Mapping 6-58