OPERATION MANAGEMENT

Technical Note 5

Facility Layout

Innovations at McDonald’s

Indoor seating (1950s)Indoor seating (1950s) Drive-through windowDrive-through window (1970s) (1970s) Adding breakfast to the menu Adding breakfast to the menu

(1980s)(1980s) Adding play areas (1990s)Adding play areas (1990s)

Three out of the four are Three out of the four are layout decisions!layout decisions!

Facility Layout

Facility layout can be defined as the process by which the placement of departments, workgroups within departments, workstations, machines, and stock-holding points within a facility are determined.

Characteristics of a Good Layout

Layout Design Considerations

Higher Higher utilization of spaceutilization of space, equipment, , equipment, and peopleand people

Improved Improved flow of informationflow of information, materials, , materials, or peopleor people

Improved Improved employee moraleemployee morale and safer and safer working conditionsworking conditions

Improved Improved customer/client interactioncustomer/client interaction

FlexibilityFlexibility

Basic Layout Formats

Process Layout

Product Layout

Group Technology (Cellular) Layout

Fixed-Position Layout

Process-Oriented Layout

Design places departments with large flows of material or people together

Dept. areas have similar processes, eg all lathes in one area & all stamping machines in another

Used with process-focused processes

© 1995 Corel Corp.

Layout Types

FoundryMilling

machines

LathesGrinding

Painting Drills

Office

Welding

Forging

(a) Process Layout(a) Process Layout

Can handle a variety of processing requirements

Not particularly vulnerable to equipment failures

Equipment used is less costly Possible to use individual incentive

plans

Advantages of Process Layouts

In-process inventory costs can be high Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Complexities often reduce span of

supervision

Disadvantages of Process Layouts

Product-Oriented Layout

Equipment is arranged according to the steps by which the product is made.

Used when batch size is large Types: Fabrication line; assembly line Examples

© 1984-1994 T/Maker Co.

Layout Types

(b) Layout of a production line(b) Layout of a production line

Station 1 Station 2 Station 3 Station 4

1 2 3 4

5

6

78910

In

Out

Workers

Figure 6.6A U-Shaped Production Line

High rate of output Low unit cost Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling Fairly routine accounting and

purchasing

Advantages of Product Layout

Creates dull, repetitive jobs Poorly skilled workers may not

maintain equipment or quality of output Fairly inflexible to changes in volume Highly susceptible to shutdowns Needs preventive maintenance Individual incentive plans are

impractical

Disadvantages of Product Layout

Cellular Layout - Group Technology (Work Cells)

Groups dissimilar machines into work centers (or cells) to work on similar products.

Group Technology

Machine 1

Machine 2

Machine 3

Machine 4Machine

5

Materials in

Finished goods out

One Worker, Multiple MachinesOne Worker, Multiple Machines

Group TechnologyDrilling

D D

D D

Grinding

G G

G G

G G

Milling

M M

M M

M M

Assembly

A A

A A

Lathing

Receiving and shipping

L

L L

L L

L L

L

(a) Jumbled flows in a job shop without GT cells(a) Jumbled flows in a job shop without GT cells

Group Technology

(b) Line flows in a job shop with three GT cells (b) Line flows in a job shop with three GT cells

Cell 3

L M G G

Cell 1 Cell 2

Assembly area

A A

L M DL

L MShipping

D

Receiving

G

Fixed-Position Layout

Design is for stationary project Workers & equipment come to site Complicating factors

– Limited space at site

Examples

© 1995 Corel Corp.

© 1995 Corel Corp.

© 1995 Corel Corp.

Fixed Position Layout

Question: What are our primary considerations for a fixed position layout?

Answer: Arranging materials and equipment concentrically around the production point in their order of use.

Process Layout: Interdepartmental Flow Given

– The flow (number of moves) to and from all departments

– The cost of moving from one department to another

– The existing or planned physical layout of the plant

Determine– The “best” locations for each department, where

best means interdepartmental transportation, or flow, costs

Process Layout Example

1.1. Construct a “from-to matrix”Construct a “from-to matrix”

2.2. Determine the space requirementsDetermine the space requirements

3.3. Develop an initial schematic diagramDevelop an initial schematic diagram

4.4. Determine the cost of this layout Determine the cost of this layout

5.5. Try to improve the layoutTry to improve the layout

6.6. Prepare a detailed plan Prepare a detailed plan

Arrange six departments in a factory to Arrange six departments in a factory to minimize the material handling costs. minimize the material handling costs. Each department is 20 x 20 feet and the Each department is 20 x 20 feet and the building is 60 feet long and 40 feet wide.building is 60 feet long and 40 feet wide.

DepartmentDepartment AssemblyAssembly PaintingPainting MachineMachine ReceivingReceiving ShippingShipping TestingTesting(1)(1) (2)(2) Shop (3)Shop (3) (4)(4) (5)(5) (6)(6)

Assembly (1)Assembly (1)

Painting (2)Painting (2)

Machine Shop (3)Machine Shop (3)

Receiving (4)Receiving (4)

Shipping (5)Shipping (5)

Testing (6)Testing (6)

Number of loads per weekNumber of loads per week

50 100 0 0 20

30 50 10 0

20 0 100

50 0

0


Figure 9.4Figure 9.4

Room 1Room 1 Room 2Room 2 Room 3Room 3

Room 4Room 4 Room 5Room 5 Room 6Room 660’60’

40’40’


Receiving Shipping TestingDepartment Department Department

(4) (5) (6)


Assembly Painting Machine ShopDepartment Department Department

(1) (2) (3)

100100

5050

2020

5050

5050

20201010

100100

3030


Interdepartmental Flow GraphInterdepartmental Flow Graph

1 2 3

4 5 6



Cost Cost == $50$50 ++ $200$200 ++ $40$40(1 and 2)(1 and 2) (1 and 3)(1 and 3) (1 and 6)(1 and 6)

++ $30$30 ++ $50$50 ++ $10$10(2 and 3)(2 and 3) (2 and 4)(2 and 4) (2 and 5)(2 and 5)


= $570= $570

Cost = Cost = ∑ ∑∑ ∑ X Xijij C Cijij

nn

i i = 1= 1

nn

j j = 1= 1

Room 1Room 1 Room 2Room 2 Room 3Room 3

Room 4Room 4 Room 5Room 5 Room 6Room 660’60’

40’40’


Receiving Shipping TestingDepartment Department Department

(4) (5) (6)


Painting Assembly Machine ShopDepartment Department Department

(2) (1) (3)


3030

5050

1010

5050

50502020

5050 100100

100100

Interdepartmental Flow GraphInterdepartmental Flow Graph

2 1 3

4 5 6



Cost Cost == $50$50 ++ $100$100 ++ $20$20(1 and 2)(1 and 2) (1 and 3)(1 and 3) (1 and 6)(1 and 6)



= $480= $480

Cost = Cost = ∑ ∑∑ ∑ X Xijij C Cijij

nn

i i = 1= 1

nn

j j = 1= 1

Other considerations in Process Layout

For an 8 department problem, there are 8! (or 40,320) possible arrangements.

Factors other than material handling cost are important.

Shipping & Receiving dept cannot be in the center

Sewing cannot be adjacent to Painting

Computer Software

Graphical approach only works for Graphical approach only works for small problemssmall problems

Computer programs are available to Computer programs are available to solve bigger problemssolve bigger problems CRAFT (Computerized Relative CRAFT (Computerized Relative

Allocation of Facilities Technique)Allocation of Facilities Technique)

Process Layout: Systematic Layout Planning Numerical flow of items between departments

– Can be impractical to obtain– Does not account for the qualitative factors that

may be crucial to the placement decision Systematic Layout Planning

– Accounts for the importance of having each department located next to every other department

– Is also guided by trial and error» Switching departments then checking the results of

the “closeness” score

Systematic Layout Planning

10

Systematic Layout Planning--Example: Reasons for Closeness

Code

1

2

3

4

5

6

Reason

Type of customer

Ease of supervision

Common personnel

Contact necessary

Share same price

Psychology




Product LayoutInput Data and Activities

1. Flow of Materials 2. Activity Relationships

3. Relationship Diagram

4. Space Requirements 5. Space Available

6. Space Relationship Diagram

7. Modifying Considerations 8. Practical Limitations

9. Develop Layout Alternatives

10. Evaluation

An

alys

isS

earc

hS

elec

tio

n

Product-Oriented Layout

Equipment is dedicated to a particular product line

Assembly lines are special case of product layout

© 1984-1994 T/Maker Co.

Product Layout

Assembly Lines– A progressive paced assembly linked by some

sort of material handling device. Assembly Line Type Differences

– Material handling devices– Line configuration– Pacing (machine or human)– Product mix– Workstation characteristic– Length of line

Product Layout: Key Terms

Product Interval Time– The time between products being completed (processed

through) at a single station (process step). Also cycle time or takt time.

Product Duration (Throughput) Time.– The overall time required to entirely complete an

individual product.

Assembly Line Balancing– Assignment of tasks to workstations within a given cycle

time and with minimum idle worker time.

Assembly Line Balancing Steps

1. Specify the sequential relationships among tasks using a precedence diagram.

2. Determine the required takt (T) time.

3. Determine the theoretical minimum number of workstations (Nt) required to satisfy the takt time constraint.

4. Select a primary rule by which tasks are to be assigned to workstations and a secondary rule to break ties.

Assembly Line Balancing Steps (cont’d)

5. Assign tasks, one at a time, to the first workstation until the sum of the task times is equal to the takt time. Continue assigning tasks to other workstations until all tasks are assigned.

6. Evaluate the efficiency of the resulting assembly line.

7. If efficiency is unsatisfactory, rebalance the line using a different decision rule in step 4.

Takt Time and Throughput Time on an Assembly Line

Matching task time to takt time:1. Split the task2. Duplicate the station3. Share the task4. Use a more skilled worker5. Work overtime6. Redesign the product

Exhibit 8.9Exhibit 8.9

Assembly Line Balancing Formulas

units)(in day per Output

dayper timeProduction Takt time (T)

Takt time (T)

Sum of task times (S) Number of workstations

Takt time (T)workstations (Na)ofnumber Actual

Sum of task times (S)Efficiency

Assembly Steps and Times for Model J Wagon


Precedence Graph for Model J Wagon


A Balance Made According to Largest Number of Following Tasks Rule

Exhibit 8.12aExhibit 8.12a

Precedence Graph for Model J Wagon

Exhibit 8.12BExhibit 8.12B

Efficiency Calculation

Exhibit 8.12CExhibit 8.12C

%77,77.04.505

195orEfficiency

NT

SEfficiency

Flexible Line Layouts

Exhibit 8.13Exhibit 8.13Source: Robert W. Hall, Attaining Manufacturing Excellence (Homewood, IL: Dow Jones-Irwin, 1987), p. 125.

FIGURE 15–4

Improving Layouts by Moving to the Cellular Manufacturing Concept

Source: Source: Barry Render and Jay Heizer, Principles of Operations Management, 2nd ed., © 1997. Reprinted by permission of Prentice Hall, Inc., Upper Saddle River, NJ. G.Dessler, 2003

Group Technology (Cellular) Layout

Benefits– Better human relations in small work teams.– Improved operator expertise from the limited

number of parts and quick production cycle.– Less work-in-process inventory and material

handling due to reduced number of production stages.

– Faster production setup from faster tooling changes.

Group Technology (GT) Layout

Developing a GT Layout– Grouping parts into families that follow a

common sequence of steps.– Identifying dominant flow patterns of parts-

families for location of processes.– Physically grouping machines and processes

into cells.

Facilities Layout for Services

Goals of Service Facility Layouts– Minimize travel time for workers and customers– Maximize revenues from customers

Types of Service Layouts– Process layout—emergency rooms– Product layout—cafeteria line– Fixed-position layout—automobile repair shop

Facilities Layout for Services

Servicescape– The aspects of the physical surroundings in a

service operation that can affect a customer’s perception of the service received.

– Ambient conditions» Noise, lighting, and temperature

– Spatial layout and functionality» Minimizing employee travel time and maximizing

revenue opportunities from customers

– Signs, symbols, and artifacts» Objects that create positive images of the firm

Documents

OPERATION MANAGEMENT