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Facility Layout

Dr. Richard Jerz

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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. • Understand line-balancing problems.

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Layout

• Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system

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Strategic Importance of Layout

Proper layout enables:• Higher utilization of space, equipment, and

people• Improved flow of information, materials, or

people• Improved employee morale and safer

working conditions• Improved customer/client interaction• Flexibility• Cost, time, utilization

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Layout Strategy Concerns

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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

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Basic Layout Types

• Process Layout• Layout that can handle varied processing

requirements• Product Layout

• Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow

• Fixed Position Layout• Layout in which the product or project remains

stationary, and workers, materials, and equipment are moved as needed

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Process, or Functional Layout

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Designing Process Layouts

• Requirements:• List of departments• Projection of work flows• Distance between locations• Amount of money to be invested• List of special considerations

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Developing a Process Layout

1. Construct a “from-to matrix”2. Determine space requirements for each

department3. Develop an initial schematic diagram4. Determine the cost of this layout5. By trial-and-error (or more sophisticated

means), try to improve the initial layout6. Prepare a detailed plan that evaluates

factors in addition to transportation cost

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To-From Diagram

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100

50 30

10

50

100

1 2 3

4 5 6

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Product Layout

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A Flow Line for Production or Service

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Work Cells

• Reorganizes people and machines into groups to focus on single products or product groups

• Group technology identifies products that have similar characteristics for particular cells

• Volume must justify cells• Cells can be reconfigured as designs or

volume changes

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Group Technology: Workcells

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Cellular Manufacturing Layout

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Part A

Part B

Asse

mbl

y

Part C

Part D

Lathe

Lathe

Mill

Mill

Mill

Mill

Drill

Drill

Drill

Heat treat

Heat treat

Heat treat

Gearcut

Gearcut

Grind

Grind

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1 2 3 4

5

6

78910

In

Out

Workers

A U-Shaped Production Line

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Advantages of Work Cells

• Reduced work-in-process inventory• Less floor space required• Reduced raw material and finished goods

inventory• Reduced direct labor• Heightened sense of employee participation• Increased use of equipment and machinery• Reduced investment in machinery and

equipment

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Fixed-Position Layout

• Example: Airplanes• Design is for stationary project • Workers and equipment come to site• Complicating factors

• Limited space at site• Changing material needs

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Layout Variables to Evaluate

• Equipment utilization• People utilization• Inventory• Inspection• Transportation• Cycle time

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Computer Programs for Layout

• CRAFT• SPACECRAFT• CRAFT 3-D• MULTIPLE• CORELAP• ALDEP• COFAD• FADES - expert system

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Computerized Layout

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Computerized Layout

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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.

• Objectives• Maximize efficiency• Minimize number of

work stations

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Precedence Diagram

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Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements

a b

c d e

0.1 min.

0.7 min.

1.0 min.

0.5 min. 0.2 min.

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Assembly Line Balancing Equations

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Cycle time = Production time available

Demand per day

Minimum number of work stations

Σ Task times

Cycle time

Efficiency =

=

Σ Task times

* (Cycle time)(Actual number of work stations)

Cycle time = Production time available

Demand per day

Minimum number of work stations

Σ Task times

Cycle time

Efficiency =

=

Σ Task times

* (Cycle time)(Actual number of work stations)

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Line Balancing Rules

• Assign largest tasks first• Assign tasks in order of most following

tasks.• 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.

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Some Heuristic (intuitive) Rules:

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Improving Line Balance

• Smaller time elements• Better methods analysis• Better tools• Buffers• Parallel workstations

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