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Chapter 10

Facility Layout

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OUTLINE

What Is Layout Planning? Types of Layouts Designing Process Layouts Special Cases of Process Layouts Designing Product Layouts Designing Hybrid Layouts

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What Is Layout Planning?

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What Is Layout Planning

Layout planning is determining the best physical arrangement of resources within a facility

Facility resource arrangement can significantly affect productivity

Two broad categories of operations: Intermittent processing systems – low volume of

many different products Continuous processing systems – high volume of a

few standardized products

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Types of Layouts

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Types of Layouts

Four basic layout types consisting of; Process layouts - Group similar resources

together Product layouts - Designed to produce a

specific product efficiently Hybrid layouts - Combine aspects of both

process and product layouts Fixed-Position layouts - Product is too large

to move; e.g. a building

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Process Layouts Process layout unique characteristics

include;

General purpose & flexible resources

Facilities are more labor intensive

Lower capital intensity & automation

Higher labor intensity

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Process Layouts - continued Processing rates are slower

Material handling costs are higher

Scheduling resources & work flow is more complex

Space requirements are higher

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Product Layouts

Product layout unique characteristics Produce small number of products

efficiently Resources are specialized High capital intensity Low flexibility relative to the market

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Product Layouts - continued

Processing rates are faster

Material handling costs are lower

Lower space requirements

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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

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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

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Designing Process Layouts

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Designing Process Layouts Step 1: Gather information:

Space needed, space available, importance of proximity between various units

Step 2: Develop alternative block plans: Using trial-and-error or decision support tools

Step 3: Develop a detailed layout Consider exact sizes and 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

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Process Layout Steps Step 1: Gather information like space needed, from-to

matrix, and REL Chart for Recovery First Sports Medicine Clinic (total space 3750 sq. ft.)

ARadiology

400 sq. ft.

BLaboratory

300 sq. ft.

CLobby & Waiting

300 sq. ft.

DExamining

Rooms800 sq. ft.

ESurgery & Recovery900 sq. ft.

FPhysical Therapy

1050 sq. ft.

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Step 1: Gather Information

(continued)

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Step 2: Develop a New Block Layout Use trial and error with from-to or REL Charts as a guide Use computer software like ALDEP or CRAFT

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Decision Support Tools Trial and error method good for simple

problems Layout problems are combinatorial,

3x2 office layout has 6! Options (6*5*4*3*2*1 = 720 options)

Computer programs are available decision support tools ALDEP based on REL and CRAFT based on

form-to matrix

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Special Cases of Process Layouts

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Special Cases of Process Layouts

There are a number of unique process layouts which include

Warehouse layouts

Office Layouts

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Warehouse Layouts

Warehouse Layout Considerations: Primary decision is where to locate each

department relative to the dock Departments can be organized to minimize “ld”

totals Departments of unequal size require

modification of the typical ld calculations to include a calculation of the “ratio of trips to area needed”

The usage of “Crossdocking” modifies the traditional warehouse layouts; more docks, less storage space, and less order picking

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Office Layouts Office Layout Considerations:

Almost half of US workforce works in an office environment

Human interaction and communication are the primary factors in designing office layouts

Layouts need to account for physical environment and psychological needs of the organization

One key layout trade-off is between proximity and privacy

Open concept offices promote understanding & trust

Flexible layouts incorporating “office landscaping” help to solve the privacy issue in open office environments

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Designing Product Layouts

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Designing Product Layouts Product layouts are different than process

layouts Product layouts provide for sequential product

movement that enhances efficiency Designing product layouts requires

consideration of Sequence of tasks to be performed by each

workstation Logical order Speed considerations – line balancing

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Designing Product Layouts - continued

Step 1: Identify tasks & immediate predecessors Step 2: Determine the desired output rate Step 3: Calculate the cycle time Step 4: Compute the theoretical minimum number of workstations Step 5: Assign tasks to workstations (balance the line) Step 6: Compute efficiency, idle time & balance delay

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Step 1: Identify Tasks & Immediate PredecessorsExample 10.4 Vicki's Pizzeria and the Precedence Diagram

Immediate Task TimeWork Element Task Description Predecessor (seconds

A Roll dough None 50B Place on cardboard backing A 5C Sprinkle cheese B 25D Spread Sauce C 15E Add pepperoni D 12F Add sausage D 10G Add mushrooms D 15H Shrinkwrap pizza E,F,G 18I Pack in box H 15

Total task time 165

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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):

sec./unit 60

units/hr 60

sec/min 60x min/hr 60

units/hroutput desired

sec./day time available)(sec./unit time Cycle

hourper pizzasor units/hr, 72sec./unit 50

sec./hr. 3600

time task bottleneck

time availableoutput Maximum

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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

stations 3or 2.75,

nsec/statio 60

seconds 165

time cycle

times taskTM

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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 finishedWorkstation Eligible task Task Selected Task time Idle time

A A 50 10

B B 5 5

C C 25 35

D D 15 20

E, F, G G 15 5

E, F E 12 48

F F 10 38

H H 18 20

I I 15 5

1

2

3

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Last Layout Calculation 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%

91.7%100sec. 60x stations 3

sec. 165

NC

t (%) Efficiency

8.3%91.7%100%delay Balance

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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 un-paced lines Paced lines use an automatically enforced cycle

time

Number of products produced Single-model line Mixed-model line

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Designing Hybrid Layouts

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Designing Hybrid 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

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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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Facility Layout Across the Organization

Layout planning is organizationally important for an efficient operations Marketing is affected by layout especially

when clients come to the site Human resources is affected as layout

impacts people Finance is involved as layout changes can

be costly endeavors

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The End