04ME71104GT (1)

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GROUP TECHNOLOGY INMANUFACTURING SYSTEMS

Facility Layout 2

Machine shop process layout

Receiving Grinders

Mills

Raw material. Large number

of

storage Assembly low volume

products

Drills

Planers

Finished

Inspection goods

Lathes Automatics storage

Part A

Part B

WHAT ARE THE TYPICAL PROBLEMS ?

If batches of work arrive in random order at a machine

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WHAT ARE THE TYPICAL PROBLEMS ?If batches of work arrive in random order at a machine

High proportion of available time may be spent on resetting,retooling etc between the batches of dissimilar items.[shapes/Sizes]

Parts are to be carried through various functionaldepartments-complexities in management

This leads to delay in throughput and piling of stocks in eachdepartment.

ALL THESE PROBLEMS NEED TO BE OVERCOME

Non value added activities?

Facility Layout 7

Product layout

Raw material. Fabrication

Receiving storage line-part B

Fabrication Planer

line-part A

Finished Lathe

goods Drill

storage Mill

Mill

Drill

Grinder

Mill

Assembly line Automatic

Small number

ofhigh volumeproducts

ASSEMBLY LINE FOR EACH

PRODUCT CAN BE

COUNTER PRODUCTIVE

What is the better option ?

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Group Technology (GT)

GT is a manufacturing philosophy whosemain idea is to capitalize on similarrecurrent activities

Application of GT principles inmanufacturing is Cellular ManufacturingSystems ( CMS)

Applicable in other functional areas suchas design, production control and

purchasing

In GT :family of functionally and geometricallysimilar parts are processed on their requisite

machines placed together and close in acell and as far as possible in the sequentialorder of processing

Cellular Manufacturing

Cellular manufacturing is the physicaldivision of manufacturing facilitysmachinery into production cells

Each cell is designed to produce a familyof parts

A family of parts is defined as a set ofparts that require similar machinery,tooling and/ or jigs and fixtures

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THE NECESSITY OF GT Consumer tastes are changing from time to time.

Manufacturing has to resort to low volume and highvariety schedules

Small Batch production has its own problems.

Job Shop production would result in higher costs

Flow line production is economically justifiable forstable and large demand.

GT has been developed to counter this inverse

relationship between Lot size and Manufacturing costs.

GT enjoys the advantage of similarities inManufacturing and Design.

ProductLayout

CombinationLayout

ProcessLayout

Q

P

P-Q Charts indicating that different layouts are justified

M

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PART NUMBERS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

A

B

C

D

E

F

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N

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(A). PART-MACHINE DATA

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PART NUMBERS

2 11 12 19 21 25 7 9 15 1 3 5 13 14 16 18 20 23 4 6 8 10 17 22 28 24 262

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B

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A

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(B) AFTER SORTING INTO FAMILIES AND GROUPS

Group 1

Group 2

Group 3

Family 1

Family 2

Family 3

Exception

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GENERAL BENEFITS OF GT.

There are four major areas under which

the benefits can be identified.Setting time

Layout

Flow control

Human Factors

SIGNIFICANT BENEFITS OF CMS

Reduction in

Setup time

Work-in-process inventory

Material Handling Cost

Equipment and direct/indirect labor cost

Improvement in

Quality

Material flow

Machine Utilization Space utilization

Employee morale

There are various methods Empirical approach

Production Flow Analysis ( PFA)

Part Classification and coding

Single Linkage Clustering Algorithm(SLCA)

Rank Order Clustering ( ROC)

Heuristics

P-Median

Simulated Annealing

Genetic Algorithm

PRODUCTION FLOW ANALYSIS

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LOGICAL STAGES IN PRODUCTION

FLOW ANALYSIS

Company flow analysis

Factory flow analysis

Group analysis

Line analysis

Tooling analysis

Production Flow Analysis (PFA) It is a technique used for improving the workflow

in a company by finding the production cells.

It involves analysis of the planning and routecards of all components manufactured.

It is used to analyze the operation sequence andmachine routing for the parts produced.

It groups parts with similar and identical routings.

Groups thus created form cells.

It uses the basic manufacturing data.

It is principally concerned with existing methodsof manufacturing.

Does not consider other features such asmaterial form etc.

P.F.A the method

Collect information on all parts and machines.

Assign number to each part and machine.

Prepare machine- component matrix. This matrix should display the components processed on machine. Should also indicate the machines required for each component. This is basically machine component incident matrix. This matrix is also termed as production flow analysis chart (PFA Chart).

Carryout the analysis. From the pattern of information displayed on PFA CHART. Basic groups must be

discerned. Rearrange either the list of processes (M/CS) or the list of parts. This will help bringing together the graphical information, which is called PFA chart after

rationalization. Decide upon the basic groups. Examine individually those operation routes, which lie outside any group. Check whether their routing or method of manufacture be altered. Enable them to fit into a group.

Balance the load in each group

- Total the actual work content for each group by considering each operation in it.

- Further check and refine the organization of each group

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PART NUMBERS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

A

B

C

D

E

F

G

H

I

J

K

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N

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M

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PART NUMBERS

2 11 12 19 21 25 7 9 15 1 3 5 13 14 16 18 20 23 4 6 8 10 17 22 28 24 262

7

B

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N

A

C

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Group 1

Group 2

Group 3

Family 1

Family 2

Family 3

Exception

THREE CORE STAGES IN PFA


Factory flow analysis concerned with the first major division into large

group of departments and large families of part to be made in these

departments.

Group analysis

Group analysis is concerned with the division of the plant assigned to

each department into group the division of parts into associa ted

families.

The primary aim is to achieve the simplest possible material flow system inside

each department. For this three sec ondary aims are adopted.

1.As far as possible, each part should be processed in one group only.

2.Each machine type should exist in one group only.

3.Incompatible proces ses should be in different groups.

Line analysis

Line analysis is concerned with the flow of materials between the machines inside the

group and planning the best layo ut for machines, with the aim of finding the sequence ofmachines that will give the nearest approximation to line flow.

The three core stages are progressivesub-techniques of production flowanalysis.

Each should be completed in the ordermentioned.

Two more techniques can be added.

Company flow analysis precedes factoryflow analysis. This is applicable to largecompanies with several factories.

Tooling analysis follows line analysis.


To combine the processing units during processes on the same parts

into larger units called major groups.

It is done in 10 main steps1. Divide into processing units

2. Allocate parts to processing units3. Determine process route number (prn)4. Analyze by PRN5. Draw basic flow chart6. Simplify the basic flow chart and form major group7. Determine which parts are exceptions8. Eliminate exceptions9. Check loads on machine10.Specify the s tandard inter major group material flow systems

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Group analysis

Uses a matrix to divide all parts assigned to a major group in such away that each family can be completed processed by one group.

The primary aim of group analysis is to find the most efficient division ofthe major group of a required size.

The group analysis takes place in the following eight steps

1. Renumber operations on route cards2. Sort route cards into packs

3. Draw pack-machine chart or component-machine chart4. Find families and group

5. Check loads and allocate plant6. Investigate and eliminate exceptions

7. Specify groups and families

8. Draw final flow analysis

Production flow analysis

It is the tooling analysis.

It again uses a matrix and finds the division ofthe parts processed on each machines intotooling families and also to find their optimumsequence of loading.

The objective is to find the parts which use thesame tooling set up so that if they are producedin the same sequence of loading then the tool

change time can be minimized.

EXAMPLE FOR PRODUCTION FLOW ANALYSIS

INPUT MATRIX

Operation 1 2 3 4 5 6 7 8 9 10 11 12

1 x x x x x

2 x x x x

3 x x x

4 x x x x x

5 x x x x x x

6 x x x x x x x

7 x x x x x x

8 x x x x x x x x

INITIAL MATRIX

Operation

1 2 12 7 3 11 9 8 6 5 4 10

1 x x x x x

2 x x x X

3 x x X

4 x x x x x

5 x x x x x X

6 x x x x x x X

7 x x x x x X

8 x x x x x x x X

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Overview of PFA

1. Data collection.

Part numbers, machines, machine routings.

Production volume [lot size], production rate.

2.Sorting of process routings.

Part number, process sequence with machinecode

Packs groups of part with identical processroutings.

3.PFA charts.

Analysis

Final solution.

Parts classification and coding

It is concerned with identifying similarities among partsand relating to a coding system.

There are two types of part similarities

Design attributes:Material, geometric shape, size etc.

Manufacturing attributes:Machines, process, sequence of processing, tooling etc

Some of the common methods of coding Visual inspection.

Classification and coding by examination of design and

production data. Other methods such as OPITZ, MICLASS etc.

McAuley`s similarity coefficient

Single Linkage Clustering Algorithm

( SLCA)

Find the similarity coefficient S(j,k) for the machines j and k It is the ratio of the sum of the parts which visit both machines to the sum of

the parts which visit both machines and the sum of the parts which visitonly one of the two machines

The similarity between each pair of machines is examined . Group of machines are formed, such that, within each group, the objects are

similar to each other according to predefined set of rules.

The basic procedure is to first cluster together those machines related withthe highest possible similarity coefficient.

Then the level of admission is gradually reduced by steps of predeterminedequal magnitude.

The admission of a machine into cluster is done by using the criterion ofsingle linkage.

If the defined similarity level will admit a machine into a cluster, then asingle link at that level with any member of that cluster will allow admission.

A dendogram is used to graphically represent the output.

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Single Linkage Cluster Analysis (SLCA)

Machine i

YES NO

YES N (y) N (j )

Machine

j

NO N ( i.) N (N)

Similarity coefficient s( i , j ) =

N ( y ) / {N ( y ) + N ( i ) + N ( j ) }

Example: There are five parts and thr ee machines

Machines P1 P2 P3 P4 P5

1 1 1 0 1 1

2 1 1 0 0 1

3 1 0 1 1 0

s ( i, j ) Matrix

M/C

1 2 3

1 1 0.75 0.4

M/C 2 1 0.2

3 1

Similarity co efficient Dendogram:

M/C

1 2 3

1

0.8

S (i,j )

0.6

0.4 0.4

0.2 0.2

There are various methods Empirical approach

Production Flow Analysis ( PFA)

Part Classification and coding

Single Linkage Clustering Algorithm(SLCA)

Rank Order Clustering ( ROC)

Heuristics

P-Median

Simulated Annealing

Genetic Algorithm

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ROC

A popular method

Motivated a large number of algorithms

subsequently

What is the basis ?

M

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PART NUMBERS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

A

B

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D

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PART NUMBERS

2 11 12 19 21 25 7 9 15 1 3 5 13 14 16 18 20 23 4 6 8 10 17 22 28 24 262

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Group 1

Group 2

Group 3

Family 1

Family 2

Family 3

Exception

RANK ORDER CLUSTERING (ROC)

EXAMPLE

0 0 1 0 1 0

0 1 1 0 0 0

1 0 0 1 0 0

0 1 1 0 1 0

1 0 0 1 0 1

STEP 1 COMPONENTS

MA

C

H

I

N

E

S

SCORE RANK1 2 3 4 5 6

1

2

3

4

5

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STEP 2

1 0 0 1 0 1

1 0 0 1 0 0

0 1 1 0 1 0

0 1 1 0 0 0

0 0 1 0 1 0

COMPONENTS

1 2 3 4 5 6

M

A

C

H

I

N

E

S

5

3

4

2

1

SCORE

RANK

RANK ORDER CLUSTERING (ROC)

EXAMPLE

0 0 1 0 1 01X21 + 1X23

105

0 1 1 0 0 01X23 + 1X24

244

1 0 0 1 0 01X22 + 1X25

362

0 1 1 0 1 0

1X21 + 1X23 + 1X24

26 3

1 0 0 1 0 11X20 + 1X22 + 1X25

371

STEP 1 COMPONENTS

M

A

C

H

I

N

ES

SCORE RANK1 2 3 4 5 6

1

2

3

4

5

STEP 2

1 0 0 1 0 1

1 0 0 1 0 0

0 1 1 0 1 0

0 1 1 0 0 0

0 0 1 0 1 0

23 + 24 21 +2220+21+

2223+24 20+22 24

24 5 7 24 5 16

1 5 4 2 6 3

COMPONENTS

1 2 3 4 5 6

M

A

C

H

I

NE

S

5

3

4

2

1

SCORE

RANK

STEP 3 Score Rank

1 1 1 0 0 0 23+ 24+ 25 56 1 M/C 5

1 1 0 0 0 0 24+ 25 48 2 M/C 3

0 0 0 1 1 1 20+ 21+ 22 7 3 M/C 4

0 0 0 1 1 0 21 +22 6 4 M/C 2

0 0 0 1 0 1 20+ 22 5 5 M/C 1

1 4 6 3 2 5

24 24 16 7 6 5

1 2 3 4 5 6

COMPONENTS

SCORE

RANK

NOTE : Here after no more change in the rank order is possible.

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There is no change in the ranks. Stop.

The cluster obtained in Step #3 is used for forming CELLS

The suggested cells are:

CELL 1 : Components 1,4 and 6 ; Machines 5 and 3

CELL 2 : Components 3,2 and 5 ; Machines 4,2 and 1

MACHINES

1 1 1 0 0 0 M/C 5

1 1 0 0 0 0 M/C 3

0 0 0 1 1 1 M/C 4

0 0 0 1 1 0 M/C 2

0 0 0 1 0 1 M/C 1

1 2 3 4 5 6COMPONENTS

.

Evaluation of solutions

Number of cells

Number of duplicate machines

Number of exceptional elements

Number of voids in the cells

Grouping efficacy

EXAMPLE FOR SLCA & ROCPart machine matrix

Parts

Machine 1 2 3 4 5 6 7 8 9 10 11 12

1 1 1 0 0 0 0 1 0 1 0 0 1

2 0 0 0 1 1 1 0 0 0 1 0 0

3 0 0 0 1 0 1 0 0 0 1 0 0

4 0 0 1 0 1 1 0 0 1 0 1 0

5 1 0 0 0 1 0 1 1 0 1 1 0

6 0 1 0 1 0 0 1 0 1 1 1 1

7 0 0 1 0 0 1 0 1 1 1 1 0

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A SIMPLE ALGORITHM TO FORM CELLS

INPUT

MACHINE PART MATRIX

OUTPUT

CELLS

PARTS

MACHINES

1

2

3

4

5

6

1 2 3 4 5

1

1

1

1

1

1

1

1 1

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ALGORITHM

Find the Number of ones in each row andcolumn

Re-arrange the rows in the descending order ofthe number of ones

Apply the following procedure in the modifiedmatrix to rearrange the columnsa)Take row 1, take the columns having the ones to

the leftb) Take rows 2 to n and apply the same

procedure Use the revised matrix to form the cells.

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Evaluation of solutions

Number of cells

Number of duplicate machines

Number of exceptional elements

Number of voids in the cells

Grouping efficacy

Grouping efficacy

= (1- )/ (1+)

=numberof exceptionalelements

total number ofoperations

=numberof voids inthediagonalblocks

total number of operations

1 2 3 4 5 6 7

1 1 1 1 1

2 1

3 1 1 1 1 1 1

4 1 1 1

5 1 1 1 1

Input sample problem

Components

Machines

1 3 4 2 5 6 7

1 1 1 1 1

3 1 1 1 1 1 1

5 1 1 1

4 1 1 1

2 1 1

First solution for sample problem

Components

Machines

Exceptiona

l element

Void

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1 3 4 2 5 6 7

1 1 1 1 1

3 1 1 1

5 1 1 1

4 1 1 1

2

3

1

1

1

1 1

Second solution for sample problem

Components

Machines

Evaluation of cell configurations

Criteria Solution 1 Solution 2

Number of cells 2 2

Number of duplicate

machines0 1

Number of exceptional

elements

6 3

Number of voids in

solution

6 7

Grouping efficacy 0.5 0.6

CELL DESIGN

There are two issues

1) Forming Cells

2) Arranging the machines in the cells

A SIMPLE ALGORITHM FORARRANGING MACHINES

INPUT

MACHINE PART MATRIX

OUTPUT

CELLS

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A SAMPLE PROBLEM

Part Weekly quantity Machine routing

A 50 327

B 20 61

C 10 651

D 12 3274

E 60 51

F 5 324

G 100 3247

H 40 247

I 15 561

2

1 2 3 4 5 6 7 Score Rank

A 1 1 1 49 8

B 1 1 66 4

C 1 1 1 70 1

D 1 1 1 1 57 5

E 1 1 68 3

F 1 1 1 56 7

G 1 1 1 57 6

H 1 1 1 41 9

I 1 1 1 70 2

1 2 3 4 5 6 7

C 1 1 1

I 1 1 1

E 1 1

B 1 1

D 1 1 1 1

G 1 1 1 1F 1 1 1

A 1 1 1

2 H 1 1 1

Score 480 31 30 29 448 416 27

Rank 1 4 5 6 2 3 7

1 5 6 2 3 4 7

C 1 1 1

I 1 1 1

E 1 1

B 1 1 PF-

II

D PF-I

1 1 1 1

G 1 1 1 1

F 1 1 1

A 1 1 1

H 1 1 1

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AN ALGORITHM FOR ARRANGING MACHINES IN ACELL

Prepare FROM-TO Chart for the cell using theProcess plan

Identify the machine with To sum asminimum.

Place this machine at the beginning of thesequence.

Eliminate the row and column corresponding tothis machine and get the revised From-Tochart.

Repeat the step until all machines are placed.

Par ts in Ce ll 2 Wee kl y q ua nt it yMachine routing

A 50 327

D 12 3274

F 5 324

G 100 3247

H 40 247

CELL 2To 2 3 4 7 From sum

From 2 0 0 145 62 207

3 167 0 0 0 167

4 0 0 0 140 140

7 0 0 12 0 12

To

sum167 0 157 202

To 2 4 7 From sum

From 2 0 145 62 145

4 0 0 140 1407 0 12 0 12

Tosum

0 157 202

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To 4 7 From sum

From 4 0 140 140

7 12 0 12

Tosum

12 140

RESULT OF THE ALGORITHM FOR ARRANGINGMACHINES IN A CELL

To sum of machine 3 is the minimum.

Therefore machine 3 is placed at the beginning of thesequence.

Eliminate the row and column corresponding to machine3 to get the revised From-To chart.

To sum of machine 2 is the minimum

Hence machine 2 is placed next in the sequence.

Eliminating the row and column corresponding tomachine 2 yields the revised From-To chart.

To sum for machine 4 is the minimum

Hence the sequence is

3 2 47


There are some major areas under which


LayoutFlow control and inventory

Quality and Productivity

Human factors related

Reported Benefits of GT/CMS

52% reduction in part design

10% reduction in number of drawings

60% reduction in Industrial Engineering time

20% reduction in production floor space

40% reduction in raw material stocks

60% reduction in setup time

70% reduction in Production time

62% reduction in Work in process inventory

82% reduction in over due orders

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Limitations of GT/CMS Physical rearrangement of the existing facility can

require a great deal of expense and effort

The cost of disruption involved is difficult to justify

A manufacturing cell is less flexible to deal with

unexpected changes

Normally, grouping of machines leads to poor utilization

of some of the machines

More skill is required from the workers since they are

responsible for the operation of a wider variety of

machinery

A cell can be justified when the parts within a family have

very similar machine processes, similar sequence ofprocesses and sufficient volume to justify year-round

utilization of the cell.

FOR SUCCESSFUL

APPLICATION

GT requires several organizational

supports

GT IN INDIA

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HOW POPULAR IS GT IN INDIA

Applications ?

Some industry

QUESTIONNAIRE CONSTRUCTION

Part 1 General information about therespondents company

Part 2 Sharing of experiences regarding theimplementation of GT/CMS

Part 3 Future plans of the company in relationto implementation of GT/CMS

PROFILE OF RESPONDENTS

Respondents mainly from automobile andauto ancillary industry

Turnover ranging from 800 lac to 62000

lac Number of employees ranging from 200 to

3600

Number of products range from 10 to ashigh as 500

EXPERIENCES RELATED TO GT/CMS

Fifty percent of respondents wereunaware about GT/CMS

CMS was implemented as a part of BPR

Grouping of parts mainly on product basis Mostly practical wisdom as a basis for cell

formation

Assistance of consultants availed

Only use of PFA and ROC reported

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REASONS FOR SWITCHING OVER TOCMS

To improve flexibility and responsivenesstowards customers

To achieve proper utilization of resources

To have more focus on qualityimprovement

To face the increasing market competition

PROBLEMS IDENTIFIED BYRESPONDENTS

Getting the concept across the people.

Coordinating major activities related to CMSimplementation.

Time taken due to resistance from workers

Difficulty in sharing information within theorganization

Inability to foresee the benefits at all levels

Mindset among the line managers.

PROBLEMS IDENTIFIED BY THERESPONDENTS

Difficulties arising due to sharing of facilities

Shortage of space.

Difficulty in regrouping within the giventimeframe

Difficulties involved in retraining of theworkers

Need to follow procedures laid out by theGovernment for approval of layout in case ofPublic sector units, and

Difficulty in getting sanction from Governmentagencies like Electricity Board

MAJOR IMPEDIMENTS FOR CHANGINGOVER TO CMS

Investment in new facilities, especiallytowards duplicating the existing facilitiesto balance cells

The problems related to relayout andtheir consequences in terms of potentialdisturbances in normal operations thereof.

HOW TO OVERCOME THESE PROBLEMS?

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WHAT IS NEEDED?

A system which can provide

Help to conceptualize differentconfigurations

Facilities to generate different scenarios

Capability to simulate and look ahead

Power to analyze different situations

Vision to build effective CMS

Virtual cellular system

The grouping of machines is done only in

control software

The cell is not identified as fixed grouping

of machines

It provides a manufacturing environment

which is flexible, adaptive and

reconfigurable without considerable efforts

BUILDING THE VIRTUAL CELLSStep 1: Group products and machines

Step 2: Measure Demand and Establish Takt Time

Step 3: Review Work Sequence

Step 4: Combine Work to Balance Process

Step 5: Design Cell layout

Step 6: Evaluate the cell layout ? ?

Step 7: Repeat steps 1 to 6 with various layouts

Step 8: Choose the best alternative and use

Step 9: Identify situations for reconfiguration

Step10:Effect reconfiguration

THE DETAILS Group Products:

To identify the products that will be produced

in the cell.

Not all products can be run together through a

cell.

Existing products must be assessed to

determine which can be run through the same

cell.

Cells can accommodate mixed models, but

with certain conditions.

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Measure Demand and Establish Takt time

Once the products to be produced in a particular cell

have been identified, the demand on the cell must be

determined.

The new process must be designed to ensure that it

can meet current and projected customer demand.

Establish Takt Time

Takt Time translates daily demand into the minutes

and second required to produce the part to meet that

demand.

This allows us to compare demand to the time

required to produce the product.

What is takt time ? A process must be designed so that it will

produce a good finished product (Dont

count the bad ones!) by the end of each

cycle of Takt Time.

Takt Time sets the drum beat for the

process and the organization as a whole.

Ex: If the Takt Time is 10.4 seconds per unit,

then the process must produce a good

finished unit every 10.4 seconds in order for

it to meet demand.

Takt Time is calculated by taking Work Time

Available divided by the demand (typically

daily).

A reasonable estimate of Work Time

Available must be used.

Certainly, lunch, breaks, clean up periods andsuch cannot be included.

For most companies this amounts to about

420 minutes a shift.

Several levels of demand (and therefore

several Takt Times) can be calculated and

used in the design of the cell.

Suppose we are doing 20 mm rounds,

there are 1200 seconds available.

Lets assume demand is 115 units, 1200

/115 is 10.4 seconds.

So every 10.4 seconds, one unit mustcome off the line.

This also means one must get pulled to

the next operation every 10.4 seconds.

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ESTABLISH TAKT TIME

Takt Time = Demand Rate

GOAL: Produce to Demand

= 10.4 Sec/piece

1200 Seconds

115 pieces=

=Work Time Available

Number of Units Sold

Total work content time = Minimum # of People(stages)

Takt time

Review Work Sequence: the team will

observe the current process, step by step.

Combine Work to Balance Process : the

team will design a new process, that is

properly balanced between each resource.

Design Cell Layout: a physical layout must

be developed for the new process.

>The layout must be designed to accommodate

the work balancing that is envisioned.

>Further, the design must eliminate non value

added waste wherever possible.

REVIEW WORK SEQUENCE

Observe Sequence of Tasks EachWorker Performs

Break Operations into ObservableElements

Identify Value Added Versus NonValue Added Elements and MinimizeNVA

Study Machine Capacity, Lead Timesand Change Over Times

Smooth and steady wins the race in Cellular

Manufacturing.

A smooth flowing process will produce a

finished unit every cycle of Takt Time

throughout the shift or day.

Cellular Manufacturing is not about a processthat experiences frequent stops and starts,

but a continuously flowing process.

Time is one commodity that can never be

recovered.

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Break Operations into Observable Elements:

The more detail the better.

The information obtained here will be

important in the next step.

Identify Value Added Versus Non Value

Added Elements and Minimize NVA:

NVA elements can be identified during

observation of the process.

Ideas to eliminate or minimize the NVA

elements must be generated.

This step requires us to observe

Sequence of Tasks Each Worker

Performs:

It provides an opportunity to step out of

the process and examine is objectively.

COMBINE WORK TO BALANCEPROCESS

0

5

10

15

20

A B C D E

Operation

Unbalanced Line

0

12

34

56

78

910

A B C D E

Operation

Balanced Line

Takt Time = 10 seconds

We combine the work to balance the

process.

The Unbalanced chart shows a process

with five (5) operations, each taking a

different time to complete.

For example, Operation B takes 20

seconds to complete, while Operation C

takes 7 seconds.

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What will physically be observed at Operations B and

C?

There will be a build up of Work-in-Process (WIP) or

Starving since Operation C is completed in less time

than Operation B.

The person at Operation B will not be able to keep up.

At first he or she will try to keep up by rushing,

perhaps at the expense of quality.

However over time, the person will slow down to his

or her natural pace.

Often people in this position become frustrated, and

feel that they are being treated unfairly.

What about Operation E?

Only 7 seconds is required to complete this operation.

This person has some available time. What

additional responsibilities might we assign to this

person?

Perhaps this person is responsible for keeping an eye

on the other three operations.

It may be part of his or her responsibility to assist the

other operations when necessary by:

replenishing materials;

helping a particular operation that is falling behind

other activities.

The operations become roles on the team.

Team members should be cross trained in the

various roles.

Teams may chose to periodically change

roles.

In Cellular Manufacturing, short term

imbalances can be dealt with by teamwork.

For example, one or two activities should be

identified before and after each operation.

Team members can perform a step for the

next person if it helps them to keep up.

True imbalances must be resolved by

permanently reassigning responsibility for a

particular activity from one work station to

another.

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Likewise down the line.

The Balanced Chart shows a better balanced

process.

The Takt Time is 10 seconds.

Each operation is designed to require roughly

10 seconds to complete.

The operations are balanced to each other.

As a result, this process will flow more

smoothly and perform at a higher level.

PLANT LAYOUT DESIGN &CONSTRUCT

Design Goals Flexible layout,

Lot size = 1,

Point of use storage,

Visual Management by product family; Simplify Flows

Integrate process operations, materials flow one way

Minimize Materials Handling Concentrate on value-added motion

Establish material replenishment procedure

Make use of people 100 percent

Promote visibility, flexibility, ergonomics Operators stand for Flexibility

We design the layout for product mixed

models.

If there is varying demand, then the

process must be designed to provide

different outputs, with different levels of

staffing.

A process cannot be designed that onlyworks at maximum demand, if it is also

expected to produce at lower levels during

the year.

Lot Size 1: Ideally, a lot size of one and one piece

flow is preferred.

Point of Use Storage

>All materials must be stored within reach (approx. 3)

of the user.

>Visual signal and controls must be utilized in the cell.

>All P.O.U.S. locations must be clearly marked. If

applicable, Kanbans must be clearly defined and

displayed.

>Tools should be visible

Mixed Models: When necessary, the cell must be

designed to accommodate mixed models.

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Several important questions must be

answered.

How will the materials be changed over?

Will Work Station activities change with

different models?

What will be the impact on flow and balance?

The physical layout must include the materials

for all models expected to be produced in the

cell.

Process Documentation may have to bedeveloped to assist the transition of the cell

from model to model.

Include all operations required to produce

the product in a single cell.

For example, all sub-assembly operations

should be included.

It is easier to manage one flow than

several.

Minimize Material Handling:

>Operators should not have to bend, twist or

turn, and lift to perform the work at any station.

>All required tools and materials must be within

reach and in front of the operator.

>Operators must be able to work withoutinterruption.

>Materials are brought to the operator, instead

of the operator getting the materials.

>So, a procedure for periodically replenishing

materials must be established.

The responsibility for this important role must be

clearly defined, including

Who?

When?And How often?

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Make Use of People 100 Percent.

Promote Visibility and Flexibility:

>A U-Shaped cell offers increased

possibilities because barriers to teamwork

and communication can be eliminated and

materials can be replenished

without interrupting the cell.


There are three major areas under which


Layout

Flow control

Setting time reduction

Number of component type - Less

Component similarity - High

Results in significant reduction in setting time.

The following benefits are realized.

Enables small batch size production-reduces stocks and impro vesflexibility.

Increases m/c capacity ut ilization/efficiency. Hence more effective

capacity.

Minimum tool changes-reduction in tooling investment

Reduction in setting costs

Reduction in operating costs.

Layout

Results in Group layout

Some important implications for human aspects.

Flow simplification.

Results in a variety of benefits.

Reduction in thro ughput time-because of sm allqueue.

Improved response (Quicker) to market changes-Production is small scale and operations areautonomous.

Reduced stocks (and in Work In Progress)

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Layout

Better Delegation of responsibility( To cell in charge)

Reduced handling and setup costs.

Simplification of paperwork-more accurate costing.

Reduced indirect labour-Better cost analysis.

Improved human relations and communication

Reduced investment per output

Improved quality of work

Reduction in overdue orders-customer satisfaction

Simplified production control.

Simplified material handling.

Operator satisfied more-Reliability increased.

Worker flexibility increased. Reduced inspection-work is within and better

identification of faults.

Flow Control

Material flow is si mplified within cell Information flow is simpli fied.

RESULTS IN CERTAIN BENEFITSReduced direct material costs.

Reduced material obsolescence

Elimination of int erdepartmental stores.

Reduced material damage.

Other flow related b enefits listed in B.

DESIRABLE CHARACTERISTICS OF A CELL SYSTEM

Cells are not mere physical segregations of the manufacturingfacilities and parts into cells/Families.

Certain conditions are essential to achieve the objectives of GT

These factors decide pragmatic worth of the system [Thus setapart the abstractions of theoretical model].

These are the design parameters of the system which are involvedin the definition of the system.

They are: Cell characteristics Job characteristics Operational characteristics Layout

Cell characteristics

Number of cells Size of cell. Number of operator per cell. Total number of machine types.

Cell composition. Remainder cell.Job characteristics Job routings Number of operations per job. Number of different Job types. Job mix Due date.

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Operational characteristics

Functions of the cell. Programming. Ordering. Machine loading.

Actual operation.Layout characteristics The integrated use of conveyors for cell work flow control The semi integrated use of conveyors for the work in progress

storage and transportation purposes Simple cells without handling aids Work grouped on single machine and in particular using the

complex components approach

Other features:

Part family formation

The composite component The key machine concept The cell design using work piece statistics Facilities layout

Cell design for assembly work Organization for implementation

GT without plant reorganization

Overall policy Need for a policy on coding

Implementation team Strategy for people

The plan

Labour organization Methods of payment

Some of the common assumptionsRELATING TO CELL

Each cell is a modified flow shop.

Machines are laid out to simplify and minimize material movement.

Most machines have flexibility to perform multiple operations.

Cells have labor f lexibility.

Each is an autonomous entity with regard to tooling, inspection, labor, material etc.

Technological incompatible processes should not be coupled within the same cell.

RELATING TO COMPONENTS

For any job there is at least one feasible cell. In which all (or most) of its operations can

be done. For each part, correct route cards are available with pertinent information. (Processroutes, setting and processing times, no. of components Etc.)

As far as possible, operations of a job should not be split between cells. (This will robautonomy.)

The volume of work must justify the formation of a cell.

The part family composition and volume should ensure satisfactory load situation on themachines.

The key machines. (important and costly machine .) should be properly utilized.

If a part fits into a specialized cell, it will be assigned to that rather than the general cell.

RELATING TO OPERATIONS

A high order frequency (short cycle) must be used to cater to the variability of demand.

Planning horizon is generally infinite.

Shortages arent allowed. Mean demand per period is constant.

Single cycle ordering system must be used for components.

Prerequisites of GTTo implement GT successfully, certai n steps should be taken into consideratio n. These

are known as the desirable characteris tics of a group.

1) A reserved area for a group: A special area needs to be reserved for a group, which isprocessing a part or a family of similar parts.

2) A set of workers special to the group: The workers in a group need to be trained tohandle more than one operation, i.e. multi skilling is necessary.

3) The machines in the group: All machines required to manufacture the part or family ofsimilar parts should be brought into one group. Once the raw material enters thegroup, it should only leave a s a finished part.

4) A set of parts produced by the group: The group should be fo rmed on the basis of the

part or a family of similar parts to be produced.5) A common output target: Output target should be give n to groups at regular time

intervals, to achieve simplified production control. This also helps in planning thesequence of loading on the machines.

6) The number o f workers in a group must be small to increase the cohesion and mutualcoordination among them.

7) Supervision of groups should be group based, i.e. one supervisor should be assignedto one group only (not to functions).

8) Participatio n: To ensure more participation of workers responsibilities should betrickled down from the group foreman to the workers in decision processes.

9) Organisational and control characteri stics: Production planning methods need to bedesigned to ensure completion of parts within a group. Similarly the productioncontrol methods like scheduling of work on machines should be delegated togroups.

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SUMMARYGT / CMS offers several advantages

Improvement in managing physical flowand better visibility

Improvement in operational planning andcontrol system due to added simplicity

Reduction of setup / changeover time dueto similarity of parts

Improvement related to changes inorganizational culture such empowerment,

ownership, etc.

04ME71104GT (1)

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