Layout10

Chapter 10 – Facility Layout

Operations Management

Learning Objectives Define layout planning and its importance Identify and describe different types of

layouts Compare process layouts & product layouts Describe the steps involved in designing

both process and product layouts Explain the advantages of hybrid layouts Define the meaning of group technology &

its importance to cellular layouts

What Is Layout Planning

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

Two broad categories of operations: Intermittent processing systems Continuous processing systems

Types of Layouts 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 two large to move; e.g. a building

Process Layouts General purpose & flexible resources Lower capital intensity & automation Higher labor intensity Resources have greater flexibility Processing rates are slower Material handling costs are higher Scheduling resources & work flow is

more complex Space requirements are higher

Product Layouts

Specialized equipment High capital intensity & wide use of

automation Processing rates are faster Material handling costs are lower Less space required for inventories Less volume or design flexibility

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

Comparison of Product vs. Product Layouts

Process Layouts Product LayoutsProducts: large #, different small # efficiently

Resources: general purpose specialized

Facilities: more labor intensive more capital intensive

Flexibility: greater relative to market lower relative to market

Processing slower fasterRates:

Handling costs: high low

Space requirements: higher lower

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

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.

Step 1: Gather Information

(continued)

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

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” (see Ch.4) modifies the traditional warehouse layouts; more docks, less storage space, and less order picking

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

Designing Product Layouts 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

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

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

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

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

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

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 Single or mixed-model lines

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

Process Flows before the Use of GT Cells

Process Flows after the Use of GT Cells

Chapter 10 Highlights Layout planning is deciding on the best

physical arrangement of resources. There are four basic types of layouts: process,

product, hybrid, and fixed position. Process layouts provide flexibility to make a

variety of different products. Product layouts provide greater efficiency for one product.

The steps for designing process layouts are: gather space and closeness information, develop a block plan, and develop a detailed layout.

Chapter 10 Highlights (continued)

The steps for designing an product layout are: identify tasks and predecessors, determine output rate, determine cycle time, computing the theoretical minimum number of work stations, assigning tasks to workstations, and computing efficiency and balance delay.

Hybrids layouts combine elements from both types of layouts to increase efficiency.

Hybrid layouts combine GT analysis with cellular layout concepts .

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