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Chapter 10 - Facility Layout

Operations Management

6th Edition

R. Dan Reid & Nada R. Sanders

Learning Objectives

Define layout planning and explain its importance.
Identify and describe different types of layouts.
Describe the steps involved in designing a process layout.
Describe the two special cases of process layout.
Describe the steps involved in designing a product layout.
Explain the meaning of group technology (cell) layouts.

What Is Layout Planning?

Deciding the best physical arrangement of all resources that consume space within a facility

Facility resource arrangement can significantly affect productivity
Two broad categories of operations:
Intermittent processing systems – low volume of many different products
Repetitive processing systems – high volume of a few standardized products

Types of Layouts

Four basic layout types:
Process layouts - Group similar resources together based on similar processes/functions
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

Unique characteristics include:
Resources used are general purpose
Facilities are less capital intensive
Facilities are more labor intensive
Resources have greater flexibility
Processing rates are slower
Material handling costs are higher
Scheduling resources & work flow is more complex
Space requirements are higher

Examples:

Hospital

University

Metalworking shop

Department store

Tool & Die Manuf.

Wal-Mart

Product Layouts

Unique characteristics are:
Resources are specialized
Facilities are capital intensive
Processing rates are faster
Material handling costs are lower
Space requirements for inventory storage are lower
Flexibility is low relative to the market

Examples:

Assembly lines

See’s Candies

Cafeterias

Car Wash

Toyota

Process vs. Product Layouts

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
Group technology or cell layouts
Identification of parts of the process layout operation that can be standardized and produce them in a product layout format

Examples:

Winnebago

Retail stores

Grocery stores

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

Examples:

Construction

Dam

Bridge

Shipbuilding

Aircraft Manuf.

Designing Process Layouts

Step 1: Gather information:

Space needed, space available, identify closeness measures (From-to Matrix, REL, SLP)

Step 2: Develop alternative block plans:

Using trial-and-error or decision support tools (load-distance model, ALDEP, CRAFT)

Step 3: Develop a detailed layout:

Consider exact sizes/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

Special Cases of Process Layouts - Warehouse Layouts

Warehouse Layout Considerations:
Primary decision is where to locate each department relative to the dock
Storage areas of equal sizes
Assign departments to locations in order to minimize the number of trips to the dock.
Storage areas of unequal sizes
STEP 1: Take the ratio of the number of trips relative to the storage area required.
STEP 2: Use the ratios from Step 1 to make assignments. Assign the department with the highest ratio closest to the dock. Next, assign the department with the second-highest ratio second closest to the dock. Continue in this manner until all departments have been assigned.

Special Cases of Process Layouts - 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
Key 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

Designing product layouts requires consideration of:
Sequence of tasks to be performed by each workstation
Logical order
Speed considerations – line balancing

Designing Product Layouts – cont'd

Step 1: Identify tasks & immediate predecessors

Step 2: Determine output rate

Step 3: Determine cycle time

Step 4: Compute the Theoretical Minimum number

of Stations

Step 5: Assign tasks to workstations

(balance the line)

Step 6: Compute efficiency, idle time &

balance delay

Step 1: Identify Tasks & Immediate Predecessors

Step 2: Determine Output Rate

Output Rate is the number of units to be produced over a specific period of time
Vicki needs to produce 600 pizzas per hour

Vicki will need to divide the work among a number of people simultaneously at workstations
The goal is to design a product layout that can produce the desired number of units with the least amount of work centers and a balance of workload

Step 3: Determine Cycle Time

Determine cycle time calculations
The amount of time each workstation is allowed to complete its tasks

Limited by the bottleneck task (the longest task):

Minimum cycle time = bottleneck
Maximum cycle time = sum of the task times

Step 4: Theoretical Minimum Number of Stations

Computing the theoretical minimum (TM) 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

Step 5: Assign Tasks to Workstations

Assigning tasks to workstations (Balance the Line)
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 finished

Step 6: Efficiency and Balance Delay

Computing 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%

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
Un-paced has more autonomy; product may be removed off assembly line

Number of Product Models produced
Single-model lines – one version of a product
Mixed-model lines – many versions of a product

Group Technology (CELL) 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 and After The Use of GT Cells

Facility Layout Within OM: How It All Fits Together

Layout decisions are directly related to issues of product design and process selection (Ch 3).
Job design, as process layouts tend to require greater worker skills than do product layouts (Ch 11).
Degree of automation, as product layouts tend to be more capital intensive and use more automation compared to process layouts (Ch 3).
Layout decisions are also affected by implementation of just-in-time (JIT) systems, which dictate a line flow and the use of group technology (GT) cells (Ch 7).
As layout decisions specify the flow of goods through the facility, they impact all other aspects of operations management.

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

Chapter 10 Highlights

Layout planning is deciding on the best physical arrangement of all resources that consumes space within a facility. Proper layout planning is highly important for the efficient running of a business. Otherwise, there can be much wasted time and energy, as well as confusion.

There are four basic types of layouts: process, product, hybrid, and fixed position. Process layouts group resources based on similar processes. Product layouts arrange resources in straight-line fashion. Hybrid layouts combine elements of both process and product layouts. Fixed-position layouts occur when the product is larger and cannot be moved.

Chapter 10 Highlights – cont'd

Process layouts provide much flexibility and allow for the production of many products with differing characteristics.

Product layouts, on the other hand, provide greater efficiency when producing one type of product.

The 3 steps for designing process layouts are (1) gather information about space needs, space availability, and closeness requirements of departments; (2) developing a block plan or schematic of the layout; and (3) developing a detailed layout.

Chapter 10 Highlights – cont'd

The 6 steps for designing an product layout are (1) identify tasks that need to be performed and their immediate predecessors; (2) determine output rate; (3) determine cycle time; (4) computing the theoretical minimum number of work stations, (5) assigning tasks to workstations; and (6) computing efficiency and balance delay.

Hybrids layouts have advantages over other layout types because they combine elements of both process and product layouts to increase efficiency.

Chapter 10 Highlights – cont'd

An example of hybrid layouts is group technology or cell layouts. Group technology is the process of crating groupings of products based on similar processing requirements. Cells are created for each grouping of products, resulting in a more orderly flow of products through the facility.

Example 10.4 Vicki's Pizzeria and the Precedence Diagram

ImmediateTask Time

Work ElementTask DescriptionPredecessor(seconds

ARoll doughNone50

BPlace on cardboard backingA5

CSprinkle cheeseB25

DSpread SauceC15

EAdd pepperoniD12

FAdd sausageD10

GAdd mushroomsD15

HShrinkwrap pizzaE,F,G18

IPack in boxH15

Total task time

165

hour

per

pizzas

sec./unit

165

sec./hr.

3600

output

Maximum

hourper pizzas 8.12

sec./unit 165

sec./hr. 3600

output Maximum 

(

)

(

)

sec./unit

units/hr

sec/min

min/hr

units/hr

output

desired

sec./day

time

available

)

(sec./unit

time

Cycle

hour

per

pizzas

sec./unit

165

sec./hr.

3600

output

Maximum

(

)

stations

2.75,

sec/statio

seconds

165

time

cycle

times

task

(

)

91.7%

100

sec.

stations

sec.

165

(%)

Efficiency

8.3%

91.7%

100%

delay

Balance