15.2 Single - Factor (One - Way) Analysis of Variance

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Transcript 15.2 Single - Factor (One - Way) Analysis of Variance

Facilities Layout

Facility Layout

Facility Layout

• the arrangement of everything within and around

buildings;

• the configuration of departments, work centers and

equipment, with particular emphasis on the movement of work (customers or materials) through the system.

Facility Layout decisions arise when:

• Designing new facilities • Redesigning existing facilities

Importance of Layout Decisions



Requires substantial investments of money and effort



Involves long-term commitments



Has significant impact on cost and efficiency of short-term operations

The Need for Layout Planning

• Inefficient operations – High cost – Bottlenecks • Accidents or safety hazards • Changes in product or service design • Introduction of new products or services

The Need for Layout Planning

• Changes in output volume or product mix • Changes in methods or equipment • Changes in environmental or other legal

requirements

• Morale problems

Layout Strategy aims to..

Develop an economical layout which will meet the requirements of:



product design and volume (product strategy)



process equipment and capacity (process strategy)



quality of work life (human resource strategy)



building and site constraints (location strategy)

Layout Design Objectives

• Basic Objective – Facilitate a smooth flow of work, material, and information

through the system

• Supporting objectives – Facilitate product or service quality – Use workers and space efficiently – Avoid bottlenecks – Minimize material handling costs – Eliminate unnecessary movement of workers or material – Minimize production time or customer service time – Design for safety and security

Layout Design Objectives

•

Supporting objectives

– Facilitate communication and interaction between workers,

between workers and their supervisors, or between workers and customers

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

people

– Encourage proper maintenance activities – Provide a visual control of operations or activities – Provide flexibility to adapt to changing conditions – Maximize customer satisfaction – Improve employee morale – Improve customer/client interaction

Basic Types of Layouts



Process Layout (Functional Layout)



Product Layout



Fixed Position Layout



Combination Layouts

Process (Functional) Layout



Used with process-focused (non repetitive) processes



Layout that can handle varied processing requirements



Machines are grouped according to the process they perform. E.g. All x-ray machines in the same area



Used for intermittent processing (job shop or batch shop)



Low raw material and finished goods inventory, high WIP inventory

Process Layouts

Used for Intermittent processing (low volume, high variety) Job Shop or Batch Dept. A Dept. B Dept. C Dept. D Dept. E Dept. F

Process Layout in Services

Women’s lingerie Women’s dresses Women’s sportswear Shoes Cosmetics and jewelry Entry and display area Housewares Children’s department Men’s department

Emergency Room Layout

E.R.Triage room

Patient A broken leg Patient B - erratic pacemaker Hallway

E.R. beds

Pharmacy Billing/exit

Manufacturing Process Layout

Lathe Department L L Milling Department M M D Drilling Department D D D M M D D D D L L G G G P L L L L G G Grinding Department G P Painting Department L L Receiving and Shipping A A Assembly A

Manufacturing Process Layout

Lathe Department L L Milling Department M M D Drilling Department D D D M M D D D D L L G G G P L L L L G G Grinding Department G P Painting Department L L Receiving and Shipping A A Assembly A

Manufacturing Process Layout

Lathe Department L L Milling Department M M D Drilling Department D D D M M D D D D L L G G G P L L L L G G Grinding Department G P Painting Department L L Receiving and Shipping A A Assembly A

Process Layout

Design places departments with large flows of material or people close to each other

Process Layout: Advantages



Can handle a variety of processing requirements



Not particularly vulnerable to equipment failures



General-purpose equipment is often less costly than the specialized equipment used in product layouts



It is possible to use individual incentive plans

Process Layout: Disadvantages



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



Special attention for each product or customer



Accounting and purchasing are more involved

Product Layout



Linear arrangement of workstations to produce a specific product



Layout that uses standardized processing operations to achieve smooth, rapid, high volume flow



Requires standardized product, high production volume, stable production quantities



High equipment utilization, high investment in justified equipment, large raw material and finished goods inventories

Raw materials or customer Station 1

Product Layout

sequential Station 2 Station 3 Station 4 Finished item Material and/or labor Material and/or labor Material and/or labor Material and/or labor Used for Repetitive or Continuous Processing

Product Layout:A U-Shaped Production Line

In 1 2 3 4 5 Workers 6 Out 10 9 8 7

Mixed Model Assembly Lines



Produce multiple models in any order on one assembly line

Product Layout: Advantages

• High rate of output • Low unit cost • Labor specialization • Low material handling cost per unit • High utilization of labor and equipment • Established routing and scheduling • Routine accounting, purchasing, and inventory

control

Product Layout: Disadvantages

• Creates dull, repetitive jobs • Poorly skilled workers may not maintain equipment or

quality of output

• Fairly inflexible to changes in volume or product or

process design

• Highly susceptible to shutdowns • Preventive maintenance, capacity for quick repair and

spare-parts inventories are necessary expenses

Product Layout



Design minimizes line inbalance and delay between work stations.

Comparison Of Product And Process Layouts (1 of 2)

Description 2. Type of Process 3. Product 4. Demand 5. Volume 6. Equipment 7. Workers PRODUCT LAYOUT Sequential arrangement of machines Continuous, mass production, mainly assembly Standardized made to stock Stable High Special purpose Limited skills PROCESS LAYOUT Functional grouping of machines Intermittent, job shop batch production, mainly fabrication Varied, made to order Fluctuating Low General purpose Varied skills

Comparison Of Product And Process Layouts (2 of 2)

Inventory 9. Storage space 10. Material handling 11. Aisles 12. Scheduling 13. Layout decision 14. Goal 15. Advantage PRODUCT LAYOUT Low in-process, high finished goods Small Fixed path (conveyor) Narrow Part of balancing Line balancing Equalize work at each station Efficiency PROCESS LAYOUT High in-process, low finished goods Large Variable path (forklift) Wide Dynamic Machine location Minimize material handling cost Flexibility

Fixed Position Layouts

– – – –

Layout in which the product or project remains stationary (cannot be moved), and workers, materials, and equipment are moved as needed Generally highly skilled labor is needed Often low fixed costs Typically high variable costs

Combination Layouts



Some operational environments use a combination of the three basic layout types:



Hospitals



Supermarket



Shipyards



Some organizations are moving away from process layouts in an effort to capture the benefits of product layouts



Cellular manufacturing



Flexible manufacturing systems

Cellular Layout

Layout in which machines are gruped into a cell that can process items that have similar processing requirements.

Cellular Layout - Work Cells

• Special case of product-oriented layout - in what is

ordinarily a process-oriented facility

• Consists of different machines brought together to

make a product family

• Example: An assembly line set up to produce 3000

identical parts in a job shop

Group Technology Schemes Enable Grouping of Parts

Parts Families

A family of similar parts A family of related grocery items

Original Process Layout

Assembly 4 1 A 6 7 5 2 10 3 B C Raw materials 8 11 9 12

Revised Cellular Layout

8 4 Cell 1 2 Assembly 10 9 12 Cell 2 6 1 3 A B C Raw materials 5 Cell 3 11 7

Automated Manufacturing Cell

A Comparison of Functional and Cellular Layouts

Flexible Manufacturing System (FMS)

A group of machines designed to handle intermittent processing requirements and produce a variety of similar products (automated machining and material handling systems)

• Includes supervisory computer control,

automatic material handling, and robots or other automated processing equipment

• It is a more automated version of cellular

manufacturing

Flexible Manufacturing Systems

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Automated machining operations



Automated material handling



Automated tool changers



Computer controlled system



Designed around size of parts processed & average processing time for parts



Can process wide variety of items quickly

Flexible Manufacturing System

CNC Machine

Finished goods

Computer control room Terminal Automatic tool changer CNC Machine Pallet Parts

FMS Layouts

Service Layout

Service Layouts

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Service layouts can be categorized as: product, process, or fixed position



Service layout requirements are somewhat different due to such factors as:



Degree of customer contact

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Degree of customization

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Common service layouts:



Warehouse and storage layouts

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Retail layouts

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Office layouts

Service Layouts

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Usually process layouts due to customers needs

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Minimize flow of customers or paperwork

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Retailing tries to maximize customer exposure to products

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Computer programs consider shelf space, demand, profitability



Layouts must be aesthetically pleasing

Retail Service Layout

• Goal--maximize net profit per square foot of floor

space

Office Layout

• Design positions people, equipment, & offices

for maximum information flow

Warehouse Layout

• Design balances space (cube)

utilization & handling cost

• Similar to process layout – Items moved between dock

& various storage areas

• Optimum layout depends on • Variety of items

stored

A Good Service Layout (Servicescape) Considers

• Ambient conditions -

background characteristics such as lighting, sound, smell, and temperature.

• Spatial layout and functionality

- which involve customer circulation path planning

• Signs, Symbols, and Artifacts

- characteristics of building design that carry social significance

Layout Methodology

Process Layout Methodology Product Layout Methodology

Process Layout Methodology

Designing Process Layouts

• The main issue in designing process layouts

concerns the relative placement of the departments

• Measuring effectiveness – A major objective in designing process layouts is

to minimize transportation cost, distance, or time

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 maximizing flow, minimizing costs (materials handling costs)

Information Requirements

In designing process layouts, the following information is required:

– A list of departments to be arranged and their dimensions – A projection of future workflows between the pairs of work

centers

– The distance between locations and the cost per unit of

distance to move loads between them

– The amount of money to be invested in the layout – A list of any special considerations – The location of key utilities, access and exit points, etc. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved.

Steps in Developing a Process Layout

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Construct a “from-to matrix”

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Determine space requirements for each department

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Develop an initial schematic diagram



Determine the cost of this layout



By trial-and-error (or more sophisticated means), try to improve the initial layout



Prepare a detailed plan that evaluates factors in addition to transportation cost

Designing Process Layouts

Methods of Designing Process Layouts



Block Diagramming

 

Minimize nonadjacent loads Use when quantitative data is available



Relationship Diagramming



Based on location preference between areas



Use when quantitative data is not available

Block Diagramming (1 of 7)

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Create load summary chart

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Calculate composite (two way) movements



Develop trial layouts minimizing number of nonadjacent loads

Block Diagramming (2 of 7)

Load Summary Chart FROM/TO DEPARTMENT

Department 1 2 3 4 Composite



3 2



4 3 2 5 1 2 3 4 5 — 60

Movements

200 loads 150 loads 110 loads 100 loads 60 loads 100 — 50 200 — 100 50

Composite



5 2



5 4 4 5 50 40 —

50 60 —

Movements

50 loads 50 loads 40 loads 0 loads 0 loads

Block Diagramming (3 of 7) Load Summary Chart FROM/TO

Department 1

DEPARTMENT 1

2 3 4

Composite



3 2



4 3 2 5 1 2 3 4 5 — 60

Movements

200 loads 150 loads 110 loads 100 loads 60 loads 100 — 50 — 100 50

Composite



5 2



5 4 4 5 50 40 — 5 50 60 —

Movements

50 loads 50 loads 40 loads 0 loads 0 loads

Block Diagramming (4 of 7) Composite



3 2



4 3 2 5 110 Load Summary Chart FROM/TO Department 1 2 3 4 5

Movements

200 loads 150 loads 110 loads 100 loads 60 loads 1 — 60 2 100 — 200 1 2 3 150 4 50 4 50 200 — 60 50 40 — — 5 5 50 50 60 40 3 50

Composite



5 2



5 4 4 5

Movements

50 loads 50 loads 40 loads 0 loads 0 loads

Block Diagramming (5 of 7) Composite



3 2



4 3 2 5 Load Summary Chart FROM/TO Department 1 2 3 4 5 1 — 60 150 1 2 2 3 4 200 100 — 100 50 Grid 2 50 200 — 110 50 40 — — 3 50 60 50 40 4 5 60

Movements

200 loads 150 loads 110 loads 100 loads 60 loads

Composite



5 2



5 4 4 5

Movements

50 loads 50 loads 40 loads 0 loads 0 loads

Block Diagramming (6 of 7)

(a) Initial block diagram 1 2 3 4 5

Block Diagramming (7 of 7)

(a) Initial block diagram ( b) Final block diagram 1 2 3 4 5 1 3 2 4 5

Relationship Diagramming (Systematic Layout Planning) (1 of 2)



Used when quantitative data is not available



Muther’s grid displays preferences



Denote location preferences with weighted lines

Relationship Diagramming (Systematic Layout Planning) (2 of 2)

• 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

Relationship Diagramming Example

Production Offices O U A I A E I O U X Absolutely necessary Especially important Important Okay Unimportant Undesirable Stockroom O E A X A Shipping and receiving U U O U Locker room O O Toolroom

Relationship Diagrams

( a) Relationship diagram of original layout Offices Stockroom Locker room Toolroom Shipping and receiving Production Key: A E I O U X

Relationship Diagrams

( b) Relationship diagram of revised layout Stockroom Offices Toolroom Production Shipping and receiving Locker room Key: A E I O U X

Product Layout Methodology

Designing Product Layouts



Suitable for production/assembly lines



Jobs are divided into work elements



Precedence diagram of tasks is developed



Work elements are assigned to workstations by trying to balance the amount work of each workstation

Product Layout: Line Balancing

Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements. X Why is line balancing important?

• To allow us to use labor and equipment more

efficiently.

• To avoid fairness issues that arise when one

workstation must work harder than another.

Product Layout

Work 1 Work Station Station 3 2 Belt Conveyor 4 Work Station 5 Office Note: 5 tasks or operations; 3 work stations

Line Balancing Concepts (1 of 2)



Precedence diagram



Network showing order of tasks and restrictions on their performance



Cycle time



Maximum time allowed at each workstation to complete its set of tasks on a unit

Line Balancing Concepts (2 of 2)

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?

Station 1 Station 2 Station 3

Minutes per Unit

6 7 3

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.

Line Balancing

Cycle time example

C d =

production time available desired output rate

C d =

(8 hours x 60 minutes / hour) (120 units)

C d

480 = = 4 minutes 120

Flow Time vs Cycle Time



Cycle time = max time allowed at each workstation to complete its set of tasks on a unit. (establishes the output rate of a line)



Flow time = time to complete all stations 1 4 minutes 2 4 minutes 3 4 minutes Flow time = 4 + 4 + 4 = 12 minutes Cycle time = max (4, 4, 4) = 4 minutes

Line Balancing Objectives

maximize efficiency - minimize the number of work stations

How Many Workstations are Needed?

• The required number of workstations is a function of – Desired output rate – Our ability to combine tasks into a workstation • Theoretical minimum number of stations

min  

Cycle time where

 min

Efficiency

Efficiency of the Line i i



= 1

nC a t i

Minimum number of workstations

i i



= 1

t i C d

where

t i j n C a C d

= completion time for element

= number of work elements = actual number of workstations = actual cycle time = desired cycle time

Balance Delay

• Balance delay (percentage of idle time of a line) Balance Delay  Idle time per cycle

N actual

 Cycle time where

Line Balancing Process

1. Draw and label a precedence diagram.

2. Estimate task times 3. Calculate the desired cycle time required for the line.

4. Calculate the theoretical minimum number of workstations.

5. Group tasks into workstations, recognizing cycle time and precedence constraints.

6. Calculate the efficiency of the line.

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

Precedence Diagram

• Precedence diagram – A diagram that shows elemental tasks and their

precedence requirements

Assigning Tasks to Workstations

Some Heuristic (Intuitive) Rules:

– Assign tasks in order of most following tasks • Count the number of tasks that follow – Assign tasks in order of greatest positional

weight.

•

Positional weight is the sum of each task’s time and the times of all following tasks.

Line Balancing (Example 1)

A B C D WORK ELEMENT Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package PRECEDENCE — A A B, C TIME (MIN) 0.1

0.2

0.4

0.3

Line Balancing (Example 1)

A B C D WORK ELEMENT Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package PRECEDENCE — A A B, C TIME (MIN) 0.1

0.2

0.4

0.3

B 0.2

0.1

A D 0.3

C 0.4

Line Balancing (Example 1)

A B C D WORK ELEMENT Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package PRECEDENCE — A A B, C TIME (MIN) 0.1

0.2

0.4

0.3

C d

0.2

6,000 units B 2400 = = = 0.4 minute 6000

0.1

A D 0.3

0.1 + 0.2 + 0.3 + 0.4

= = = 2.5 workstations 0.4

1.0

0.4

C 0.4

3 workstations

Line Balancing (Example 1)

A B C D WORK ELEMENT Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package PRECEDENCE — A A B, C TIME (MIN) 0.1

0.2

0.4

0.3

B 0.2

0.1

A D 0.3

C d N

= 0.4

= 2.5

C 0.4

Line Balancing (Example 1)

WORKSTATION ELEMENT REMAINING TIME REMAINING ELEMENTS 0.1

A B 0.2

D 0.3

C 0.4

C d N

= 0.4

= 2.5

Line Balancing (Example 1)

WORKSTATION 1 ELEMENT A REMAINING TIME 0.3

REMAINING ELEMENTS B, C 0.1

A B 0.2

D 0.3

C d N

= 0.4

= 2.5

C 0.4

Line Balancing (Example 1)

WORKSTATION 1 ELEMENT A B REMAINING TIME 0.3

0.1

REMAINING ELEMENTS B, C C, D

C d N

= 0.4

= 2.5

0.1

A B 0.2

D 0.3

C 0.4

WORKSTATION 1 2

Line Balancing (Example 1)

ELEMENT A B C REMAINING TIME 0.3

0.1

0.0

REMAINING ELEMENTS B, C C, D D

C d N

= 0.4

= 2.5

0.1

A B 0.2

D 0.3

C 0.4

WORKSTATION 1 2 3

Line Balancing (Example 1)

ELEMENT A B C D REMAINING TIME 0.3

0.1

0.0

0.1

REMAINING ELEMENTS B, C C, D D none B 0.2

C d N

= 0.4

= 2.5

0.1

A D 0.3

C 0.4

WORKSTATION 1 2 3

Line Balancing (Example 1)

ELEMENT A station 1 B A, B C 0.3 D minute REMAINING TIME station 2 0.3

0.0

0.4 0.1

minute REMAINING ELEMENTS station 3 B, C D C, D D 0.3 none minute B 0.2

C d N

= 0.4

= 2.5

0.1

A D 0.3

C 0.4

WORKSTATION 1 2 3

Line Balancing (Example 1)

ELEMENT A station 1 B A, B C 0.3 D minute REMAINING TIME station 2 0.3

0.0

0.4 0.1

minute REMAINING ELEMENTS station 3 B, C D C, D D 0.3 none minute B 0.2

C d N

= 0.4

= 2.5

1 A 3(0.4) 1.0

C 1.2

0.4

D 0.3

Line Balancing (Example 2)

• You’ve just been assigned the job a setting up an

electric fan assembly line with the following tasks: Task

A B C D E F G H

Time (Mins) Description

2 Assemble frame 1 3.25

1.2

Mount switch Assemble motor housing Mount motor housing in frame 0.5

1 1 1.4

Attach blade Assemble and attach safety grill Attach cord Test

Predecessors

None A None A, C D E B F, G

Line Balancing (Example 2) Structuring the Precedence Diagram

Task Predecessors

A None B C D A None A, C

Task Predecessors

E D F G H E B E, G A B G H C D E F

Line Balancing (Example 2) Precedence Diagram

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

2 A 1 B 1 G 1.4

H C 3.25

D 1.2

E .5

F 1

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

Line Balancing (Example 2) Determine Cycle Time

Question: Suppose we want to assemble 100 fans per day. What would our cycle time have to be? Answer:

Production time per period

Required Cycle Time,

C = Required output per period 420 mins / day C = 100 units / day = 4.2 mins / unit

Line Balancing (Example 2) 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 t Sum of task times (T) Cycle time (C) 11.35 mins / unit = 2.702, or 3 4.2 mins / unit

2 A C 3.25

1 B D 1.2

Station 1

Line Balancing (Example 2)

1 G E .5

F 1 1.4

H Station 2

Task

A C D B E F G H

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3

2 A C 3.25

1 B 1 G D 1.2

E .5

Station 1 A (4.2-2=2.2) F 1 1.4

H Station 2

Task

A C D B E F G H

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3

2 A C 3.25

1 B 1 G D 1.2

E .5

Station 1 A (4.2-2=2.2) B (2.2-1=1.2) F 1 1.4

H Station 2

Task

A C D B E F G H

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

H Station 2

Task

A C D B E F G H

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

Task

A C D B E F G H Station 2 C (4.2-3.25)=.95

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

Task

A C D B E F G H Station 2 C (4.2-3.25)=.95

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3 Idle = .95

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

Task

A C D B E F G H Station 2 C (4.2-3.25)=.95

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 3 D (4.2-1.2)=3 Idle = .95

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

Task

A C D B E F G H Station 2 C (4.2-3.25)=.95

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

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

Idle = .95

2 A C 3.25

1 B 1 G D 1.2

E .5

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

F 1 1.4

Task

A C D B E F G H Station 2 C (4.2-3.25)=.95

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

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

F (2.5-1)=1.5

Idle = .95

2 A C 3.25

1 B D 1.2

1 G E .5

F 1 1.4

Task

A C D B E F G H

Followers

6 4 3 2 2 1 1 0

Time (Mins)

2 3.25

1.2

1 0.5

1 1 1.4

Station 1 Station 2 Station 3 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) C (4.2-3.25)=.95

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

F (2.5-1)=1.5

H (1.5-1.4)=.1

Idle= .2

Idle = .95

Idle = .1

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

Efficiency of the Assembly Line

Sum of task times (T) Efficiency = Actual number of workstations (Na) x Cycle time (C) Efficiency = 11.35 mins / unit (3)(4.2mins / unit) =.

901

Balance Delay (Percent Idle Time)

Percent idle time = Idle time per cycle (N)(CT) = (.2+.95+.1)/3(4.2) = .099

Efficiency = 1 – Percent idle time

Parallel Workstations

1 min.

30/hr.

1 min.

30/hr.

2 min.

30/hr.

Bottleneck

30/hr.

2 min.

1 min.

60/hr.

1 min.

Parallel Workstations

30/hr.

2 min.

30/hr.

1 min.

30/hr.

1 min.

60/hr.

Computerized Line Balancing

Use heuristics to assign tasks to workstations



Ranked positional weight



Longest operation time



Shortest operation time



Most number of following tasks



Least number of following tasks

Balancing U-Shaped Lines

Precedence diagram: A B C Cycle time = 12 min D E

Balancing U-Shaped Lines

Precedence diagram: A B C Cycle time = 12 min D ( a) Balanced for a straight line A,B C,D E 9 min 12 min 3 min 24 Efficiency = = = .6666 = 66.7 % 3(12) 24 36 E

Balancing U-Shaped Lines

Precedence diagram: A B C Cycle time = 12 min D E (a) Balanced for a straight line A,B C,D E 9 min 12 min 3 min 24 Efficiency = = = .6666 = 66.7 % 3(12) 24 36 (b) Balanced for a U-shaped line A,B C,D E 24 Efficiency = = = 100 % 2(12) 24 24 12 min 12 min

15.2 Single - Factor (One - Way) Analysis of Variance

Transcript 15.2 Single - Factor (One - Way) Analysis of Variance

Facilities Layout

Layout Methodology

Process Layout Methodology

Balancing U-Shaped Lines

Balancing U-Shaped Lines

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