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Chapter 10 – Facility Layout
Operations Management by R. Dan Reid & Nada R. Sanders 4th Edition © Wiley 2010 © Wiley 2010
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Learning Objectives Define layout planning and explain its importance
Identify and describe different types of layouts Compare process layouts & product layouts Describe the steps involved in designing a process layout Describe the steps involved in designing a product layout Explain the advantages of hybrid layouts Define the meaning of group technology (cell) layouts © Wiley 2010
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Layout Planning Layout planning is deciding the best physical arrangement of all resources that consumes space within a facility Facility resource arrangement can significantly affect productivity and quality of products/services Two broad categories of operations: Intermittent processing systems – low volume of many different products Continuous processing systems – high volume of a few standardized products © Wiley 2010
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Types of Layouts Four basic layout types consisting of:
Fixed-Position layouts - Product is too large to move; e.g. a building Process layouts - Group similar resources together Product layouts - arrange activities according to sequence of operations for a particular product/service Hybrid layouts - Combine aspects of both process and product layouts © Wiley 2010
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Underlying Process Relationship Between Volume and Standardization Continuum
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Fixed-Position Layout
Used when product is large Product is difficult or impossible to move, i.e. very large or fixed All resources must be brought to the site Scheduling of crews and resources is a challenge © Wiley 2010
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Process Layout in Services
Women’s lingerie Women’s dresses Women’s sportswear Shoes Cosmetics and jewelry Entry and display area Housewares Children’s department Men’s department © Wiley 2010
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Manufacturing Process Layout
D G A Receiving and Shipping Assembly Painting Department Lathe Department Milling Department Drilling Department Grinding P © Wiley 2010
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A Product Layout In Out © Wiley 2010
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Process vs. Product Layouts
Here are the characteristic differences between a process and product layout. © Wiley 2010
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Hybrid Layouts Combine elements of both product & process layouts
Maintain some of the efficiencies of product layouts Maintain some of the flexibility of process layouts Examples: Group technology & manufacturing cells Grocery stores © Wiley 2010
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Original Process Layout
B Raw materials Assembly 1 2 3 4 5 6 7 8 9 10 11 12 © Wiley 2010
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Revised Cellular Layout
3 6 9 Assembly 1 2 4 8 10 5 7 11 12 A C B Raw materials Cell 1 Cell 2 Cell 3 © Wiley 2010
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Designing Process Layouts
Step 1: Gather information: Space needed, space available, identify closeness measures Step 2: Develop alternative block plans: Using trial-and-error or decision support tools Step 3: Develop a detailed layout: Consider exact sizes/shapes of departments and work centers including aisles and stairways Tools like drawings, 3-D models, and CAD software are available to facilitate this process © Wiley 2010
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Computerized layout Solutions
CRAFT Computerized Relative Allocation of Facilities Technique CORELAP Computerized Relationship Layout Planning PROMODEL and EXTEND visual feedback allow user to quickly test a variety of scenarios Three-D modeling and CAD integrated layout analysis available in VisFactory and similar software © Wiley 2010
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Designing Service Layouts
Must be both attractive and functional Types Free flow layouts encourage browsing, increase impulse purchasing, are flexible and visually appealing Grid layouts encourage customer familiarity, are low cost, easy to clean and secure, and good for repeat customers Loop and Spine layouts both increase customer sightlines and exposure to products, while encouraging customer to circulate through the entire store © Wiley 2010
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Types of Store Layouts © Wiley 2010
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Designing Product Layouts
Designing product layouts requires consideration of sequence of tasks to be performed by each workstation in a logical order Goal: Maximize production capacity, i.e., the line must be as balanced as possible © Wiley 2010
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Cycle time = max (4, 4, 4) = 4 minutes
Flow Time vs Cycle Time Cycle time = max time spent at any station Flow time = time to complete all stations 1 2 3 4 minutes Flow time = = 12 minutes Cycle time = max (4, 4, 4) = 4 minutes © Wiley 2010
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Designing Product Layouts – con’t
Step 1: Identify tasks & immediate predecessors Step 2: Determine output rate Step 3: Determine cycle time Step 4: Compute the Theoretical Minimum number of Stations Step 5: Assign tasks to workstations (balance the line) Step 6: Compute efficiency, idle time & balance delay © Wiley 2010
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Step 1: Identify Tasks & Immediate Predecessors
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Layout Calculations Step 2: Determine output rate
Vicki needs to produce 60 pizzas per hour Step 3: Determine cycle time The amount of time each workstation is allowed to complete its tasks Limited by the bottleneck task (the longest task in a process): © Wiley 2010
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Layout Calculations (continued)
Step 4: Compute the theoretical minimum number of stations TM = number of stations needed to achieve 100% efficiency (every second is used) Always round up (no partial workstations) Serves as a lower bound for our analysis © Wiley 2010
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Layout Calculations (continued)
Step 5: Assign tasks to workstations Start at the first station & choose the longest eligible task following precedence relationships Continue adding the longest eligible task that fits without going over the desired cycle time When no additional tasks can be added within the desired cycle time, begin assigning tasks to the next workstation until finished © Wiley 2010
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Layout Calculations (Continued)
Step 6: Compute efficiency and balance delay Efficiency (%) is the ratio of total productive time divided by total time Balance delay (%) is the amount by which the line falls short of 100% © Wiley 2010
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Other Product Layout Considerations
Shape of the line (S, U, O, L): Share resources, enhance communication & visibility, impact location of loading & unloading Paced versus unpaced lines Paced lines use an automatically enforced cycle time Number of Product Models produced Single Mixed-model lines © Wiley 2010
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Group Technology (CELL) Layouts
One of the most popular hybrid layouts uses Group Technology (GT) and a cellular layout GT has the advantage of bringing the efficiencies of a product layout to a process layout environment © Wiley 2010
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Process Flows before the Use of GT Cells
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Process Flows after the Use of GT Cells
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Chapter 10 Highlights Layout planning is deciding on the best physical arrangement of all resources within a facility. There are four basic types of layouts: process, product, hybrid, and fixed position. Process layouts provide more flexibility while product layouts provide greater efficiency. The steps for designing process layouts are (1) gather information about space needs, space availability, and closeness requirements of departments; (2) developing a block plan or schematic of the layout; and (3) developing a detailed layout. The steps for designing an product layout are (1) identify tasks that need to be performed and their immediate predecessors; (2) determine output rate; (3) determine cycle time; (4) computing the theoretical minimum number of work stations, (5) assigning tasks to workstations; and (6) computing efficiency and balance delay. Hybrids layouts (e.g., group technology or cell layouts) combine elements of both process and product layouts to increase efficiency. Group technology first groups products based on similar processing requirements. Cells are created for each grouping of products, resulting in a more orderly flow of products through the facility. © Wiley 2010
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