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Facility Layout

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General Observations• Facility Planning includes planning for: (1) the number of facilities and

general facility type, (2) facility capacity, (3) facility locations, and (4) facility layout (process choice).

• Facility layout refers to resource positioning and ultimately the material and people flows as well as the space necessary for the operation and support of operations.

• Regardless of whether it’s a manufacturing or a service facility, the design process is dependent upon the objective(s): (1) low cost per unit, (2) short order response time, and (3) flexibility.

• The central focus of many facility layouts producing standardized (make-to-stock) goods or services is to minimize the cost per unit and throughput time.

• The central focus of many facility layouts producing customized (make-to-order) goods or services is to maximize the range of offerings that can be accommodated.

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Strategic Importance

1. Capital investment and dollar investment in process design

2. Long-term commitment (cost of making alterations)3. Process choice constrains the short-term rate of

output 4. Relationship between design and productivity

(operating efficiency)5. Effects competitiveness (e.g., delivery speed, barrier

to market entry)

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Types of Processes

• Two broad categories: (1) intermittent (batch) and (2) repetitive (continuous)

• Most significant differences: (1) volume (batch size), (2) variety, (3) degree of customization or standardization

• Continuum of choice: Project Process Jumbled Process Line Process Continuous Process

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Key Contrasting Differences Between Jumbled and Line Processes

Jumbled Process Line ProcessFunctional layout Task layoutVariable path work flow Unidirectional (fixed) path work flowCustomized orders Standardized OrdersLow volume High volumeHigh variety Low varietyHigh flexibility Low flexibilityLow fixed costs/high variable High fixed costs/low variableLabor intensive Capital intensiveGeneral purpose equipment Special purpose equipmentHigh skill labor requirements Low skill labor requirementsEasy capacity changes Difficult capacity changesChaotic planning environment Stable planning environment

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Product Life Cycle

Volume

Introduction Growth Maturation Plateau time

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Product and Process Matrix: Matching the Product and Production Process Life Cycles

Life Cycle Stage Introduction Growth Maturation Plateau

Jumbled Flow Economically Infeasible

dangerCellular

Assembly Line danger

Continuous Economically Infeasible

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Jumbled Layouts for both Manufacturing and Service Facilities

• Typically: early life cycle items, generally low demand, nonstandard 1. Common Design Objectives

a. Flexibility (process, product, and volume)b. Minimize load/distance traveled

2. Strategies to Achieve Objectives a. Place resources that have high workload exchanges in close proximity

b. Easy redesign capabilities (e.g., partitions, machines on wheels)3. Process-focused layout design information requirements a. Space requirements: list of departments, work centers, or items to be arranged, their approximate

dimensions, and the dimensions of the building that will house the items. b. Projection of work flows between various work centers, item throughput volumes, or closeness

preference (REL) ratings c. The distance between locations and the cost per unit of distance to move loads (items) between

various locations. d. The budget for the layout design.

e. A list of special considerations (e.g., location of loading docks, windows, aisle widths)4. Example Solution Techniques a. Linear programming methods b. Heuristic Methods

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Evaluating Jumbled Process Solution Quality

1. Sum of load distance products2. Sum of relationship (REL) scores

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Line Process for both Manufacturing and Service Facilities

• Typically: mature life cycle items, high demand, standardized

1. Common Design Objectives a. Low cost per unit

b. Rapid order response time

2. Strategies to Achieve Objectives a. High resource utilization rates (equalized workloads)

b. High throughput volume and worker productivity (successive production stages in close proximity)c. Reduced material movements (many material entry points)

3. Layout Design Process: assembly line balancing = equal performance times a. Identify elemental tasks, precedence requirements, and time standards

b. Determine desired (required) output ratec. Design Parameters: (1) Maximum possible output = Time available per day/bottleneck task time (2) Minimum possible output = Time available per day/sum of all task times (3) Target cycle time (must be > to largest task time) = Time available per day/ Desired (required) output (4) Theoretical minimum number of work stations = Sum of all the task times/ Cycle Time

d. Allocate tasks to work stations: Heuristics

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Evaluating Line Process Solution Quality

1. Actual number of workstations

• Good basis for predetermining solution quality is the theoretical minimum number of workstations

2. Efficiency = Sum of all the task times /(Number of stations * Cycle time)

3. Workload balance

4. Psychological factors (enrichment, specialization, etc.)

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Additional Managerial Considerations

1. Control variance2. Cross-training workers3. Parallel workstations4. Incompatible tasks and zoning constraints

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Cellular (Hybrid) Layouts

1. Determine part families using group technology

2. Arrange equipment into manufacturing cells, each containing the equipment used to process a particular family of component parts, typically U-shaped or C- shaped

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Common Performance Metrics1. Throughput time: the average amount of time a product takes to move through the system. 2. Process Velocity similar to throughput times but it also takes into account the waste of time spent

waiting ; determined as the ratio of:

Throughput time/Value-added Time 3. Productivity: measures how well a company uses its resources, and is generally determined as:

Output/Input 4. Utilization: measures the proportion of time a resource is actually used, and is determined as:

Time a resource is used/Time a resource is available 5. Efficiency: measures performance relative to a standard, and is determined as:

Actual output/Standard output