week-3.1 line balancing

8/3/2019 Week-3.1 Line Balancing

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Work Analysis and Design

Line Balancing

Ayse AKBALIK-RAPINE

January 2011

End 202 - Work analysis and design Line Balancing
http://find/http://goback/


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Problem solving steps

1 Select project (Pareto, Fish diagram, Gantt, PERT,

Job/Worksite analysis guide)

2 Get and present data (charts, computations)

3 Analyze data (operation analysis)4 Develop ideal method (motion, work, equipment design)

5 Present and install method (decision making tools)

6 Develop job analysis

7 Establish time standards (time study)8 Follow up



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Line Balancing -ideal case-

See Beyond Lean page

Everyone is doing the same amount of work

Variation is smoothed

No one overburdened

No one waiting

Everyone working together in a balanced fashion



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Line Balancing

Example 1

Operation 1 = 5 min

Operation 2 = 15 min

Operation 3 = 10 min

Questions

What is the cycle time of this system?

If each operation was 15 min, what happens?If we consider Operation 2 = 10 min ?



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Line Balancing

Example 1

What is the system efficiency?

What is the idle time percentage?



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Line Balancing

Example 1

What is the system efficiency?

efficiency% = ( total actual standard minutestotal allowed standard minutes

)%

efficiency% = (

lead timenumber of machines

bottleneck time

)%



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Line Balancing

Example 2

We want 960 pieces a day (with 8h a day)

See the standard minutes for each operation below

Operation Standard minutes Number of operators

Op 1 1.2 min ?

Op 2 2.4 min ?

Op 3 1.9 min ?



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Line Balancing


Op 1 1.2 min 3Op 2 2.4 min 5

Op 3 1.9 min 4



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How to increase the efficiency of the operation 2?

1 Reassign some of the work of operation 2 to the other

operations

2 Improve the method at operation 2 to decrease the cycle

time

3 Utilize a part-time worker



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Line Balancing, Example 3


Op 1 1.25 min

Op 2 1.38 min

Op 3 2.58 minOp 4 3.84 min

Op 5 1.27 min

Op 6 1.29 min

Op 7 2.48 min

Op 8 1.28 min



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Line Balancing

Example 3

find the number of operators to assign to each operation

for a production of 700 pieces per day

minimization of the storage costs are of high importance!

no stock level is required at the end of day

which operation determines the output from the line?

find the total number of pieces produced at the end of the

day



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Assembly line improvement



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Disadvantages of element sharing

sharable parts, tasks

Increase in material handling (parts are delivered to more

than one location)

Duplication of tooling, additional costs

If any competence or experience is required from the

operators, training periods...

divisible tasks

not very economicaltwo times setup time, setup cost

decrease on the efficiency



14/20

Assembly line balancing -a precedence chart-

Operation times are given as follows:

0.46, 0.35, 0.25, 0.22, 1.10, 0.87, 0.28, 0.72, 1.32, 0.49, 0.55.



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Kilbridge and Websters Heuristic

Rank operations according to their number of

predecessors

Assign first operations with least number of predecessorsIn case of tie, choose operation with longest operation time

Total time at each work station cannot exceed the total

cycle time

Precedence relationships must be satisfied



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Helgeson and Birnie (1961) method

Compute "Positional weight = Operation time + Total time

of all operations that must follow it"

Begin by assigning the operation with highest positional

weightIf there is a tie, break it by

higher operation timelower operation number

Total time at a station cannot exceed the total cycle time

Precedence relationship must be satisfied



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Assembly line balancing -a precedence chart-



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Assembly line balancing -precedence matrix-



19/20

Assembly line balancing -positional weights-

The system cycle time = 1.5 min is given.



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Assembly line balancing -balanced assembly line-


week-3.1 line balancing

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