Ch11 Facility Layout

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Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.

2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Facility Layout Planning and Design

Sections:

1. Types of Production Plant Layouts

2. Other Types of Layouts

3. Systematic Layout Planning

Chapter 11


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Facility Layout

Refers to the size and shape of a facility as well asthe relative locations and shapes of the

functional areas (e.g., departments), equipment,

workstations, storage spaces, aisles, and

common areas (e.g., restrooms) Concerned with problems of

Laying out a new facility

Making changes in an existing facility

Also called plant layout

Usually associated with production plants


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Objectives in Layout Planning

Efficient movement of materials and people

Logical work flow and minimum travel distances

Efficient utilization of space

Safety and satisfaction of those who use the

facility

Flexibility to meet changing future requirements

Advancing the operational mission of the facility


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Types of Production Plant Layouts

1. Process layout

2. Product layout

3. Fixed-position layout

Also: Hybrids of the three basic types


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Important Factors in Plant Layout

Q= production quantity - number of units of agiven part or product that the facility produces

Low production - 1 to 100 units

Medium production - 100 to 10,000 units

High production - 10,000 to millions of units

P= product variety - number of different

product designs or types made in the plant


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P - Q Relationship in Plant Layout


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Process Layout

Layout in which equipment is arranged according tofunction

Suited to low and medium production quantities

and medium to high product variety

Different parts or products are processedthrough different operations in batches

Each batch follows its own routing

No common work flow followed by all work

units

Material handling activity is significant


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Process Layout


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Product Layout

Layout in which workstations and equipment arelocated along the line of flow of the work units

Suited to high production quantities and low

product variety

Work units typically moved by poweredconveyor

At each workstation, a small amount of the total

work content is accomplished on each work unit

Each station specializes in its task, thusachieving high efficiency


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Product Layout for Assembled Product


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Comparisons

Feature Process Layout Product LayoutAnnual Q Low or medium High

Product variety Medium to high Low

Production rate Low High

Efficiency Low HighLabor skill Skilled Unskilled

Work-in-process High WIP Lower WIP

Equipment General purpose Special purpose

Advantages Versatility to deal High production rate

with product variety High efficiency

Disadvantages Low production rate Risk of obsolescence

Batch production Limited variety


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Fixed-Position Layout

Layout in which product remains in one locationduring fabrication, and workers and equipment

are brought to the product

Suited to low production quantities and high

product variety Reason for keeping product in one location:

Product is big and heavy

Typical plants: assembly and fabrication

Much manual labor

Equipment is portable or mobile


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Fixed-Position Layout


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Hybrid Layouts

Cellular - attempts to combine the best featuresof process and product layouts

Combinations of fixed position and either

Process layout or

Product layout


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Cellular Layout

Layout in which work units flow between stations,as in a production line, but each station can cope

with a variety of part styles without the need for

time-consuming changeovers

Combination of product and process layouts Tries to combine efficiency of product layout

with versatility of process layout

Neither objective is achieved perfectly, but

it is more efficient than a process layoutand more versatile than a product layout

Based on principles of group technology


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Cellular Layout


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Other Combination Layouts

Fixed-position and process layout

Shipyard - ships made in modules

Parts fabricated in process layout

Modules built in fixed-position layout

Fixed-position and product layout

Commercial airplanes (e.g., Boeing 747)

Fabrication begins with fuselage and

proceeds through 7 or so stations wherespecialized workers assemble parts and

modules to airplane


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Layout Types for P-Q Combinations


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Other Types of Layouts

Warehouses

Projects

Service facilities

Offices


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Space Requirements

4. If workload for station i consists of multipleparts or products,

WLi= QijTcij

where Qij= quantity of part typej, Tcij=

cycle time of part typej

5. Determine total area required for each

workstation type

TAi= niAi


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Space Requirements

6. Determine total are in each department bysumming areas for all station types in that

department

DAk= TAi

where DAk= area of department kand

summation is carried out over all

workstation types in department k


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Step 6. Space Relationship Diagram

Extension of activity relationship diagram in whichnodes representing departments are now

assigned areas that are proportional to areas

calculated in previous step

Shapes of nodes may be changed to fit thenodes into the diagram (e.g., use rectangular

blocks rather than round nodes)

But relative positions of blocks remain as in

the last iteration of the activity relationshipdiagram


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Space Relationship Diagram

Same diagram as

before but block

sizes areproportional to

areas

Ch11 Facility Layout

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