throughput yield

7/25/2019 Throughput Yield

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Throughput Yield (TPY)

Also called First Pass Yield

Throughput Yield (TPY) is the number of acceptable pieces at the end of the end of aprocess divided by the number of starting pieces excluding scrap and rework (meaning

they are a part of the calculation).

Rework ! a part of the TPY calculation. "se the process map as a guide for evaluatingeach individual process.

TPY is used to only to measure a single process.

!ometimes only raw material is available at the start so it may be necessary to convert

the raw material to expected pieces that it should make# or use a unit of weight at thestart and weight out at the end to calculate final yield.

The unit of measure must be the same for the numerator and denominator throughout

the calculation.

$alculation (assuming all rework only takes one time to correct)%

Process 1 TPY:

&' of the ' pieces that entered Process went through Process correctly the firsttime. Therefore Process TPY * &' + ' * ,'.'-

Process 2 TPY:


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& of the &/ pieces that entered into Process 0 went through Process 0 correctly the

first time through. Therefore Process 0 TPY * & + &/ * 1.2-

Process 3 TPY:

1 of the &/ pieces that entered Process went through Process correctly the first

time. Therefore Process TPY * 1+&/ * ,'.&-

Process 0 has the lowest throughput yield but not necessarily the most costs. f ascrapped piece in Process has significantly more cost then Process it may still be in

the team3s best interest to improve. The later the process is downstream the more costare accumulated in the piece or part.

There is more direct material# direct labor# and+or manufacturing overhead in eachprocess as the part proceeds through its value stream. Process at its initiation has all

the costs in Process 0 4 the costs of Process .

There is another method to calculate TPY for a single process. f the 5P" or defects

and units are known then%

Rework involves many of the 16wastes and contains the hidden factory opportunity# it

is relevant to understand when guiding the team7s direction.

Throughput Yield# TPY# and other yield metrics can serve as baseline scores (8easure

Phase) and final scores for !ix !igma pro9ects ($ontrol Phase).

The baseline score does not have to be a :6score and often this yield metrics are easier

for team and other company employees to relate with and understand.

Final Yield (FY)

;inal Yield represents the acceptable pieces at the end of the process divided by thepieces started. The ;Y excludes scrap.

n other words# if there are the same amount of pieces at the end as there were at the

start (without any being introduced in the middle) then there is perfect ''- finalyield.


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Rework is nota part of the ;Y calculation. "se the process map as a guide forevaluating each individual process.

;Y does notdepend on the number of processes involved. t is a high level

determination the percentage of good pieces that came out of the entire processcompared to the T?% !ometimes only raw material is available at the start so it may be necessary to

convert the raw material into expected pieces that it should make# or use a unit ofweight at the start and weight out at the end for the calculation.

Calculation from aboe e!ample:

The unit of measure must be the same for the numerator and denominator throughout

the calculation.

Process Yield% &/ passed + ' entered * 20.'-

Process 0 Yield (itself)% &/ passed + &/ passed * ''-

Yield @;T?R Process 0% &/ passed + ' entered% 20.'-

Process Yield (itself)% 1 passed + &/ entered * ,'.&-

Yield @;T?R Process (also the same as the final yield of entire process)%

3" passed # $% entered

Final Yield & "'

Process has the lowest yield and probably the most cost associated since all thematerial# labor# and overhead costs are already in the pieces from the previous

processes.

;inal Yield and other yield metrics can serve as baseline scores (8easure Phase) and

final scores for !ix !igma pro9ects ($ontrol Phase). The baseline score does not have


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to be a :6score and often this yield metrics are easier for team and other company

employees to relate with and understand.

; there is known rework and it is significant to your team and company success# thenthroughput yield and rolled6throughput yield are better metrics

olled Throughput Yield (TY)

olled Throughput Yieldis the probability of the entire process producing :ero

defects. RTY is more important as a metric to use where the process has excessiverework.

!ince this rework involves many of the 16wastesand contains the hidden factoryopportunity# it is relevant to guide the team in the right direction.

RTY is the product of each process3s throughput yield# TPY.

"sing the same process as shown in the TPY example%

Calculation from aboe e!ample:

RTY * Process TPY A Process 0 TPY A Process TPY

RTY * '.,'' A '.12 A '.,'&

RTY * '.&1 * &1.-

There is a '"*$of the entire process producing :ero defects.
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RTY and other yield metrics can serve as baseline scores (8easurePhase) and final

scores for !ix !igma pro9ects ($ontrolPhase). The baseline score does not have to bea :6score and often this yield metrics are easier for team and other company

employees to relate with and understand.

@nother method to estimate RTY if the defects per unit or defects and units are

known%

+ormali,ed Yield (+Y)

=ormali:ed yield is the average yield per process step. The probability of a unit passing

through one process step or opportunity without rework.

;ormula%

where -e


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$alculation%

"sing k *

=Y * '.&1B(+)

+Y & %*".% & ".*%

There is a 1,- chance of a unit passing through one process step without rework.

@nother relationship is shown below to obtain the normali:ed defects per unit.

The normali:ed defects per unit e

throughput yield

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