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### Chapter 9

Facility Layout

Objectives of Facility Layout

Minimize material handling costs

Utilize space efficiently

Utilize labor efficiently

Eliminate bottlenecks

Facilitate communication and interaction between workers, between workers and their supervisors, or between workers and customers

Reduce manufacturing cycle time or customer service time

Objectives of Facility Layout

Eliminate waste or redundant movement

Facilitate the entry, exit, and placement of material, products, or people

Incorporate safety and security measures

Promote product and service quality

Encourage proper maintenance activities

Provide a visual control of operations or activities

Provide flexibility to adapt to changing conditions

Increase capacity

Basic Types of Layouts

Process Layout

Machines grouped by process they perform

Product Layout

Linear arrangement of workstations to produce a specific product

Fixed Position Layout

Used in projects where the product cannot be moved

Department

Lathe Department

Drilling Department

M

M

D

D

D

D

L

L

M

M

D

D

D

D

L

L

G

G

G

P

L

L

G

G

G

P

L

L

Painting Department

Grinding

Department

L

L

A

A

A

Receiving and

Shipping

Assembly

Manufacturing Process LayoutComparison Of Product And Process Layouts

1. Description Sequential arrangement Functional grouping

of machines of machines

2. Type of Process Continuous, mass Intermittent, job shop

production, mainly batch production,

assembly mainly fabrication

3. Product Standardized Varied,

made to stock made to order

4. Demand Stable Fluctuating

5. Volume High Low

6. Equipment Special purpose General purpose

7. Workers Limited skills Varied skills

Comparison Of Product And Process Layouts

8. Inventory Low in-process, High in-process,

high finished goods low finished goods

9. Storage space Small Large

10. Material Fixed path Variable path

handling (conveyor) (forklift)

11. Aisles Narrow Wide

12. Scheduling Part of balancing Dynamic

13. Layout decision Line balancing Machine location

14. Goal Equalize work at Minimize material

each station handling cost

15. Advantage Efficiency Flexibility

Fixed-Position Layouts

Typical of projects

Equipment, workers, materials, other resources brought to the site

Highly skilled labor

Often low fixed costs

Typically high variable costs

Line Balancing

- Precedence diagram
- Network showing order of tasks and restrictions on their performance
- Cycle time
- Maximum time product spends at any one workstation

desired units of output

Cd =

(8 hours x 60 minutes / hour)

(120 units)

Cd =

480

120

Cd= = 4 minutes

Line BalancingCycle time example

- Precedence diagram
- Network showing order of tasks and restrictions on their performance
- Cycle time
- Maximum time product spends at any one workstation

Flow Time vs Cycle Time

Cycle time = max time spent at any station

Flow time = time to complete all stations

2

3

4 minutes

3 minutes

4 minutes

Flow Time vs Cycle TimeCycle time = max time spent at any station

Flow time = time to complete all stations

Flow time = 4 + 4 + 4 = 12 minutes

Cycle time = max (4, 3, 4) = 4 minutes

WORK ELEMENT PRECEDENCE TIME (MIN)

A Press out sheet of fruit — 0.1

B Cut into strips A 0.2

C Outline fun shapes A 0.4

D Roll up and package B, C 0.3

Line BalancingWORK ELEMENT PRECEDENCE TIME (MIN)

A Press out sheet of fruit — 0.1

B Cut into strips A 0.2

C Outline fun shapes A 0.4

D Roll up and package B, C 0.3

0.2

B

A

0.3

0.1

D

C

0.4

Line BalancingExample 5.2

WORK ELEMENT PRECEDENCE TIME (MIN)

A Press out sheet of fruit — 0.1

B Cut into strips A 0.2

C Outline fun shapes A 0.4

D Roll up and package B, C 0.3

0.2

0.1 + 0.2 + 0.3 + 0.4

0.4

B

2400

6000

40 hours x 60 minutes / hour

6,000 units

Cd = = = 0.4 minute

A

0.3

0.1

D

1.0

0.4

N = = = 2.5 workstations

C

0.4

Line BalancingExample 5.2

WORK ELEMENT PRECEDENCE TIME (MIN)

A Press out sheet of fruit — 0.1

B Cut into strips A 0.2

C Outline fun shapes A 0.4

D Roll up and package B, C 0.3

0.2

0.1 + 0.2 + 0.3 + 0.4

0.4

B

2400

6000

40 hours x 60 minutes / hour

6,000 units

Cd = = = 0.4 minute

A

0.3

0.1

D

1.0

0.4

N = = = 2.5 workstations

C

0.4

Line Balancing3 workstations

Example 5.2

WORK ELEMENT PRECEDENCE TIME (MIN)

A Press out sheet of fruit — 0.1

B Cut into strips A 0.2

C Outline fun shapes A 0.4

D Roll up and package B, C 0.3

0.2

B

A

0.3

0.1

D

C

0.4

Line BalancingCd = 0.4

N = 2.5

Work station 2

Work station 3

0.3 minute

0.4 minute

0.3 minute

0.2

B

A, B

A

0.3

0.1

D

D

C

C

0.4

Line BalancingCd = 0.4

N = 2.5

Minimum number of workstations

Efficiency

i

i= 1

i

i= 1

ti

ti

N =

E =

nCa

Cd

Efficiency of Linewhere

ti = completion time for element i

j = number of work elements

n = actual number of workstations

Ca = actual cycle time

Cd = desired cycle time

Work station 2

Work station 3

0.3 minute

0.4 minute

0.3 minute

0.2

0.1 + 0.2 + 0.3 + 0.4

3(0.4)

B

A, B

1.0

1.2

A

0.3

0.1

D

E = = = 0.833 = 83.3%

D

C

C

0.4

Line BalancingCd = 0.4

N = 2.5

Line Balancing Process

1. Draw and label a precedence diagram.

2. Calculate the desired cycle time required for the line.

3. Calculate the theoretical minimum number of workstations.

4. Group elements into workstations, recognizing cycle time and precedence constraints.

5. Calculate the efficiency of the line.

6. Stop if theoretical minimum number of workstations or an acceptable efficiency level reached. If not, go back to step 4.

Process Layout Example

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

Construct a “from-to matrix”

Determine the space requirements

Develop an initial schematic diagram

Determine the cost of this layout

Try to improve the layout

Prepare a detailed plan

Department Assembly Painting Machine Receiving Shipping Testing

(1) (2) Shop (3) (4) (5) (6)

Assembly (1)

Painting (2)

Machine Shop (3)

Receiving (4)

Shipping (5)

Testing (6)

Process Layout Example50 100 0 0 20

30 50 10 0

20 0 100

50 0

0

Figure 9.4

Room 4 Room 5 Room 6

40’

60’

Process Layout ExampleAssembly Painting Machine Shop

Department Department Department

(1) (2) (3)

Receiving Shipping Testing

Department Department Department

(4) (5) (6)

Figure 9.5

i = 1

n

j = 1

Cost = ∑ ∑ Xij Cij

Process Layout ExampleCost = $50 + $200 + $40

(1 and 2) (1 and 3) (1 and 6)

+ $30 + $50 + $10

(2 and 3) (2 and 4) (2 and 5)

+ $40 + $100 + $50

(3 and 4) (3 and 6) (4 and 5)

= $570

i = 1

n

j = 1

Cost = ∑ ∑ Xij Cij

Process Layout ExampleCost = $50 + $100 + $20

(1 and 2) (1 and 3) (1 and 6)

+ $60 + $50 + $10

(2 and 3) (2 and 4) (2 and 5)

+ $40 + $100 + $50

(3 and 4) (3 and 6) (4 and 5)

= $480

Room 4 Room 5 Room 6

40’

60’

Process Layout ExamplePainting Assembly Machine Shop

Department Department Department

(2) (1) (3)

Receiving Shipping Testing

Department Department Department

(4) (5) (6)

Figure 9.8

Using Excel OM

- Use Operations Layout Macro
- # of departments should be # of rooms
- Input flows as given
- Make sure distance table is symmetric
- To model adjacency, put a distance of 1 for non-adjacent departments, 0 for adjacent departments
- Or use regular distance

Relationship Diagramming

Used when quantitative data is not available

Muther’s grid displays preferences

Denote location preferences with weighted lines

O

A

Offices

U

I

E

O

Stockroom

A

A

X

Shipping and receiving

U

U

U

O

O

Locker room

O

Toolroom

Relationship Diagramming ExampleA Absolutely necessary

E Especially important

I Important

O Okay

U Unimportant

X Undesirable

Locker room

Shipping and receiving

Key: A

E

I

O

U

X

Stockroom

Toolroom

Production

Relationship Diagrams(a) Relationship diagram of original layout

Figure 5.6

Offices

Shipping and receiving

Key: A

E

I

O

U

X

Toolroom

Production

Locker room

Relationship Diagrams(b) Relationship diagram of revised layout

Figure 5.6

Using Excel OM

- Operations Layout Macro can be used for Relationship Diagrams too
- Make distance table like before
- For flows table, use dummy flows:
- A = 100,000 O = 100
- E = 10,000 U = 10
- I = 1,000 X = 0

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