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GROUP TECHNOLOGY

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HISTORY OF GROUP TECHNOLOGY

•In 1925, R.Flanders presented a paper at American Society of Mechanical Engineers (USA) in which he described a way of organizing manufacturing at Jones and Lamson Machine Company.•In 1937, A.Sokolovskiy (USSR) proposed that parts having similar configuration can be produced by standard sequences. •In 1949, A.Korling (Sweden) presented a paper called “Group Production”. In this paper he described how to decentralize the work into independent groups.•H.Optiz in Germany developed the well-known parts classification and coding system for machined parts that bears his name.•In the United States, the first application of group technology was at the Langston D1-vision of Harris-Intertype in New Jersey around 1969.

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PRODUCTION FLOW ANALYSIS (PFA)

Production Flow Analysis is the method of identifying part families and associated machine groupings that uses the information contained on production route sheet rather than on part drawings (Design)

Strategy:1. Parts having similar design having different manufacturing

routes.2. Parts having different design having similar manufacturing

routes.

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PROCEDURES IN PFA

DATA COLLECTION

SORTATION OF PROCESS ROUTES

PFA CHART

CLUSTER ANALYSIS

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1. Grouping of parts and machines into families.

2. Arranging the machines into group technology cell.

Grouping parts and machines by Rank Order Clustering:The rank order clustering technique is specifically applicable in production flow analysis. It is an efficient and easy-to-use algorithm for grouping machines into cells.

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1x28+0x27+0x26+1x25+0x24+0x23+0x22+1x21+0x20= 256+32+2= 290

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ARRANGING MACHINES IN A G.T CELL

After part-machine groupings have he en identified by rank

order clustering or other method. the next problem is to

organize the machines into the most logical arrangement. Two

simple yet effective methods suggested by Hollier

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FROM

TO

1 2 3 4

1 0 5 0 25

2 30 0 0 15

3 10 40 0 0

4 10 0 0 0

FROM

TO From Sum

1 2 3 4

1 0 5 0 25 30

2 30 0 0 15 45

3 10 40 0 0 50

4 10 0 0 0 10

To sum

50 45 0 40

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FROM

TO From Sum

1 2 4

1 0 5 25 30

2 30 0 15 45

4 10 0 0 10

To sum

40 05 40

FROM

TO From Sum

1 4

1 0 25 25

4 10 0 10

To sum 10 25

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Tie breaker rules:Minimum “To sum” value machine should be place at the beginning of the sequence.a) If a tie occurs between minimum "To" sums or minimum

"From" sums, then the machine with the minimum "From/To" ratio is selected.

b) If both "To" and "From" sums are equal for a selected machine, it is passed over and the machine with the next lowest sum is selected.

c) If a minimum "To" sum is equal to a minimum "From" sum, then both machines are selected and placed at the beginning and end of the sequence, respectively.

Result:3 2 1 4

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FROM

TO From Sum

From/To sum

1 2 3 4

1 0 5 0 25 30 0.60

2 30 0 0 15 45 1.0

3 10 40 0 0 50 Infinity

4 10 0 0 0 10 0.25

To sum

50 45 0 40 135

In Hollier method II, High “From/To” ratio machine should be place at the beginning.

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Performance Measures for Alternative Machine Sequence in II GT

Number of in-sequence move = 40+30+25= 95Number of backtracking move = 5+10= 15 Percentage of in-sequence move = 95/135 = 70.4%Percentage of backtracking move = 15/135 = 11.1%