Facility Layout Facility Layout

Technical Note 6

Facility Layout DefinedFacility 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.

This process requires the following inputs:

Specification of objectives of the system in terms of output and flexibility.

Estimation of product or service demand on the system.

Processing requirements in terms of number of operations and amount of flow between departments and work centers.

Space requirements for the elements in the layout.

Space availability within the facility itself.

Basic Production Layouts

Product Layout Layout that uses standardized processing operations to

achieve smooth, rapid, high volume flow.

Process Layout Layout that can handle varied processing requirements.

Fixed-Position Layout Layout in which the product or project remains

stationary, and workers, materials, and equipment are moved as needed.

Basic Production Layouts

Cellular Manufacturing (Layout) Layout in which machines are grouped into a cell that can

process items that have similar processing requirements

Group Technology The grouping into part families of items with similar design

or manufacturing characteristics

Job shop

Batch

Assembly line

Continuous flow

Layout Structures

Process Layout (Job Shop)

FED

A B CProduct 1

Product 2

Product 3

Product 1

Product 2

Product 3

Process Layout – Position of equipment is dominant consideration

Process-Focused Strategy

Facilities are organized by process Similar processes are together

Example: All drill presses are together

Low volume, high variety products ‘Jumbled’ flow Other names

Intermittent process Job shop

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 Focused Strategy - Pros & Cons

Advantages greater process flexibility more general purpose equipment lower initial capital investment

Disadvantages more “specialist” trained personnel

required more difficult production planning and

control

Product Layout (Flow Shop)

FED

A B C

Product 2

Product 3

Product 1

FED

Product 2

Product 3

Product 1

Product Layout – Flow of product is dominantconsideration

Product-Focused Strategy

Facilities are organized by product High volume, low variety products Where found

Discrete unit manufacturing Continuous process manufacturing

Other names Line flow production (flow shop) Continuous production

Product-Focused StrategyPros & Cons

Advantages lower labor skills easier production planning and control higher equipment utilization

Disadvantages lower product flexibilitymore specialized equipmentusually higher capital investment

Group Technology:Transition from Process Layout

1. Grouping parts into families that follow a common sequence of steps.

2. Identifying dominant flow patterns of parts families as a basis for location or relocation of processes.

3. Physically grouping machines and processes into cells.

Departmental (Batch Process) Specialization

Saw Saw

Lathe PressPress

Grinder

LatheLathe

Saw

Press

Heat Treat

Grinder

Batch/Lot Thinking

Corrected

Press

Lathe

Grinder

Grinder

A

2

BSaw

Heat Treat

LatheSaw Lathe

PressLathe

1

Group Technology Cells

Single-Piece Flow Thinking

Assembly Line Cells

Group Technology

Benefits of Group Technology Changeover setup time reduced for tooling and

equipment Automation may be possible Operator may be specially trained with improved

expertise Quality of output improved In-process inventory reduced Productivity improved Lead time reduced Improved human relations

Fixed Position LayoutQuestion: 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.

Volume and Variety of Products

Poor Strategy(Fixed costs and cost changing to other products

are high)

Volume andVariety ofProducts

Low Volume HighVariety Process

(Intermittent)

RepetitiveProcess

(Modular)

High VolumeLow Variety

Process(Continuous)

One or very fewunits per lot

Projects

Very small runs, highvariety

Job Shops

Modest runs, modestvariety

DisconnectedRepetitive

Long runs, modestvariations

ConnectedRepetitive

Very long runs,Changes inattributes

Continuous

Poor Strategy(High variable

costs)

Aluminum part

Cell Assembly

Motor Assembly

Part Molding

Station 1

Minutes per Unit 6

Station 2

7

Station 3

3

Assembly Lines Balancing Concepts

Question: Suppose you load work into the three work stations below such that each will take the corresponding number of minutes as shown. What is the cycle time of this line?

Answer: The cycle time of the line is always determined by the work station taking the longest time. In this problem, the cycle time of the line is 7 minutes. There is also going to be idle time at the other two work stations.

Main Points of Line BalancingAn analysis of production linesNearly equally divides work between

workstations while meeting required output

Has objectives to Maximize efficiency Minimize number of

work stations

Example of Line Balancing You’ve just been assigned the job a setting

up an electric fan assembly line with the following tasks:

Task Time (Mins) Description PredecessorsA 2 Assemble frame NoneB 1 Mount switch AC 3.25 Assemble motor housing NoneD 1.2 Mount motor housing in frame A, CE 0.5 Attach blade DF 1 Assemble and attach safety grill EG 1 Attach cord BH 1.4 Test F, G

Example of Line Balancing: Structuring the Precedence Diagram

Task PredecessorsA None

A

B A

B

C None

C

D A, C

D

Task PredecessorsE D

E

F E

F

G B

G

H F, G

H

Example of Line Balancing: Precedence Diagram

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Question: Which process step defines the maximum rate of production?

Answer: Task C is the cycle time of the line and therefore, the maximum rate of production.

Example of Line Balancing: The Bottleneck

Task Time (Mins) Description PredecessorsA 2 Assemble frame NoneB 1 Mount switch AC 3.25 Assemble motor housing NoneD 1.2 Mount motor housing in frame A, CE 0.5 Attach blade DF 1 Assemble and attach safety grill EG 1 Attach cord BH 1.4 Test E, G

Max Production = Production time per day

Bottleneck time=

420 mins

3.25 mins / unit= 129 units

Total 11.35 Minutes

Example of Line Balancing: Determine Cycle Time

Required Cycle Time, C = Production time per period

Required output per period

C = 420 mins / day

100 units / day= 4.2 mins / unit

Question: Suppose we want to assemble100 fans per day. What would our cycletime have to be?

Answer:

Question: What else can the 4.2 min time be called other than cycle time?

Example of Line Balancing: Determine Theoretical Minimum Number of Workstations

Question: What is the theoretical minimum number of workstations for this problem?

Answer: Theoretical Min. Number of Workstations, N

N = Sum of task times (T)

Cycle time (C)

t

t

N = 11.35 mins / unit

4.2 mins / unit= 2.702, or 3t

Example of Line Balancing: Rules To Follow for Loading Workstations

Primary: Assign tasks in order of the largest number of following tasks.

Secondary (tie-breaking): Assign tasks in order of the longest operating time

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Station 1 Station 2 Station 3

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Station 1 Station 2 Station 3

A (4.2-2=2.2)

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

A (4.2-2=2.2)B (2.2-1=1.2)

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

Station 1 Station 2 Station 3

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

Station 1 Station 2 Station 3

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

C (4.2-3.25)=.95

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

C (4.2-3.25)=.95

Idle = .95

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

C (4.2-3.25)=.95

Idle = .95

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

D (4.2-1.2)=3

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3E (3-.5)=2.5

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3E (3-.5)=2.5F (2.5-1)=1.5

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

Which station is the bottleneck? What is the effective cycle time?

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3E (3-.5)=2.5F (2.5-1)=1.5H (1.5-1.4)=.1Idle = .1

Task Followers Time (Mins)A 6 2C 4 3.25D 3 1.2B 2 1E 2 0.5F 1 1G 1 1H 0 1.4

A (4.2-2=2.2)B (2.2-1=1.2)G (1.2-1= .2)

Idle= .2

Station 1 Station 2 Station 3

Example of Line Balancing: Determine the Efficiency of the Assembly Line

Efficiency =Sum of task times (T)

Actual number of workstations (Na) x Cycle time (C)

Efficiency =11.35 mins / unit

(3)(4.2mins / unit)=.901

Assembly Line Balancing Steps1. Determine tasks (operations)2. Determine sequence3. Draw precedence diagram4. Estimate task times5. Calculate cycle time 6. Calculate number of work stations7. Assign tasks (load workstations) 8. Calculate efficiency

Mixed-Model ProcessingShort cycle-interval (time) Production of a variety of types,

sizes, or models of a product family on the same line or within the same cell.

Example – The Fresh Bakery: Cakes

Daily sales for: 24 Product L (Lemon Pound)

12 Product M (Chocolate

Mud)

3 Product N (Nine Layer

Carrot)

What is the best schedule for these products?

What are we assuming for this schedule to work?

ExampleDaily sales for: 24 Product L

12 Product M

3 Product NStep 1 - find minimum ratio

8 L -- 4 M – 1 NStep 2- determine number of cycles

39/13 = 3

Example In order to meet daily demand, this

cycle will have to repeat 3 timesStep 3 - find the mix of the units that

is most repetitive.

LLM LLM N LLM LLMWhat are we assuming for this

schedule to work?Demand is uniform and our objective is to avoid inventory.

Summary - Comparison

Process Focus Product Focus

1. Product: Smallquantity, largevariety

1. Product: Largequantities, smallvariety

2. Equipment:General purpose

2. Equipment:Special-purpose

3. Operators broadlyskilled

3. Operators lessbroadly skilled

4. Many jobinstructions

4. Few work orders and job instructions;standardization

Bank

Process/Product Continuum

Process Focused(intermittent process)

Product Focused (continuous process)

Continuum

High variety, low volumeLow utilization

General-purpose equipment

Low variety, high volumeHigh utilization

Specialized equipment

Group Technology