Six Sigma Simulation Data Definitions and Worksheet Descriptions

Six Sigma SimulationData Definitions

andWorksheet Descriptions

Six Sigma Data Definitions 28/6/2004

Overview The purpose of this presentation is to:

Define the purpose and data contained on each Excel SixSigma-2 worksheets

Define the inter-relationships between the worksheets

Briefly describe the simulation output for a Design of Experiments (DOE)


WorksheetsThe simulation output is contained on the following 8 worksheets:

Data - cycle time and quality (defect and defective) data for each of the three operations

Automatic Component Insertion (ACI) Manual Assembly (MA) Solder

Analysis – aggregate data and basic cost statistics Hidden Cost – various yield measurements and hidden cost information Defect – summarized data for type & frequency of defects and number

of defective units Chart1, Chart2, Chart3 – I-MR & P-charts for each operation CumData – similar information to the Data worksheet plus subgroup

totals


Six Sigma Simulation Screenshot


Defect DefinitionsAutomatic Component

Insertion

Y1: Epoxy ContaminationY2: Tuner MisalignmentY3: Missing/Wrong PartsY4: Lead LengthY5: Bad AssemblyY6: Chip Skew

Manual Assembly

Y1: Reversed PartsY2: Wrong PartsY3: Leg-OutsY4: Shortened LeadsY5: Incorrect ReworkY6: Missing Parts

Solder

Y1: Missing SolderY2: Glue ContaminationY3: Solder BridgeY4: Insufficient SolderY5: Solder CompositionY6: Others


Data Worksheet Overview This worksheet presents quality results for each

processed unit (PCB) at each of the three operations

Start and End Time Total Index – The overall quality rating for the PCB Component Measure – The number of defects for each of

the six defect types Component Index – A quality rating for each of the defect

types. The PCB design allows for a predetermined number of defects before a board is either reworked or scrapped

The data on this worksheet is volatile – i.e., it is cleared prior to the subsequent simulation run.


Data Worksheet Screenshot

The Data worksheet contains similar sections for the remaining two operations – Manual Assembly (MA) and Solder.


Material Flow Process

Parts at mfgstation

(new or rework)?Manufacture

next PCBPCB

acceptable?

Scrap part

YesSend PCB to

next operationor ship

finished product

Yes Yes

NoNo

PCBscrap?

Parts atqueue?

No

Pull materialfrom queue

Send PCB backto mfg process

for rework

Yes

No

Pull partsfrom raw material

Start


Raw Material Shipment Example• A RM kit is shipped at time = 0 to start

the process. The first unit processed requires rework (Total Index = 2).

• Since there is no material in the queue prior to the next process operation, a RM kit is pulled into the queue to await processing (shipped at t = 4.22).

• The second RM kit shipped sits in the queue until the unit being reworked is either completed or scrapped.

• The first unit completes rework and is accepted at t = 8.41.

• The RM in the queue (second RM shipped) moves into the ACI process att = 8.41.

• At t = 12.61 the second unit is completed and the third RM kit is shipped directly to the queue and into the ACI process.

Data Worksheet


Cycle Time

Cycle Time for each processed unit can be determined from the start and end times on the Data worksheet for each operation by subtracting the start time from the end time for each RM unit (there may be some rounding discrepancies).

Data Worksheet CumData Worksheet


Data Worksheet - Quality Index

1. Total Index – The “final” inspection result for the processed PCB. A good PCB is denoted by “1”, a PCB requiring rework is denoted by “2”, and a scrapped PCB is denoted by “3”.

2. Component Measure – Quantitative results for process quality broken down by defect type (Y1 – Y6). These columns, with the exception of ACI defect type Y2, contain the count for the number of defects introduced for each unit processed. (ACI defect type Y2 data is the distance the tuner is off its target).

3. Component Index – A qualitative quality measurement. The six columns provide the results for each of the defect types.

There are three main, identical sections for each operation containing information on process quality:


Data Worksheet - Interpretation

Total Index Results:

The PCB must be reworked (Index = 2).

Component Measure Results:

The Tuner Misalignment (Y2) was 8.98 mm (acceptable at ≤ 20) and there was one Missing / Wrong Part (Y3) which required the PCB to be reworked.

Component Index Results:

The quality was “Good” (index = 1) for all defect types except Y3 (index = 2).



Material Flow Example:

1. On its first pass, the highlighted board fails quality inspection due to a Y4 (length of leads) defect type and is sent back for rework.

2. On the second pass through the process, it fails a second time due to a Y4 defect, but also due to a newly introduced Y3 (missing / wrong parts) defect type.

3. On the third pass through the process, these defects are corrected, however, a Y5 (bad assembly) defect type is caught at inspection.

4. Finally, on the fourth pass through the system, the PCB passed quality inspection.



ACI

Y1 Y2 Y3 Y4 Y5 Y6Good 10 9 10 9 10 0

Rework 0 1 0 1 0 10Scrap 0 0 0 0 0 0

0 1 0 1 0 200 Y1: Epoxy Contamination Y2: Tuner Misalignment Y3: Missing/Wrong Parts Y4: Length of Leads Y5: Bad Assembly Y6: Chip Skew

Defectives

Defects

Quality

In this case the system was set up to produce (a lot of) bad parts.

• The system did not produce a single non-defective PCB (all Total Index results are “2”)

• There were a total of 200 “Y6” defect types. This total is captured in the Defect worksheet, but can be calculated from the Data worksheet as shown.

• The number of reworked PCB’s, also captured on the Defect worksheet, can be calculated from the Data worksheet as shown.

• The Tuner Misalignment (Y2) distance ranged from 14.82 to 20.11. A PCB requires rework if this distance exceeds 20. This fact is captured in the Component Index section for the 9th PCB processed.

=SUM(entire Y6 column)

=COUNTIF(entire Y6 column,2)

Data Worksheet

Defect Worksheet


Analysis WorksheetThis worksheet is divided into two sections, Input and Results

Input Collects totals from the Data worksheet for number of units processed,

plus scrap and rework Details amount and location of WIP in the system at the end of the

production run

Results Calculates yields, process costs, and cycle times for each operation Determines overall raw material, process, and scrap costs per good unit Presents the cycle time per good unit and its standard deviation


Analysis Worksheet – Input SectionRM shipped prior to completing

order (in this case 200)

Total number of PCB’s processed by ACI, including good PCB’s, and those reworked (possibly more than once), and scrapped. This is the final entry in the “Process Unit” column on the “Data” worksheet.

PCB’s requiring no rework

Input Algebra (Solder):

289 PCB’s processed

- 200 Total good PCB’s

89 # of PCB’s needing rework

- 60 Recycled PCB’s

29 PCB’s reworked more than once

The Solder operation was able to process all 200 units produced by the MA process, even while reworking 89 units, due to its shorter CT.


The cost parameters are fixed

Data pulled from simulation

Analysis Worksheet – Input Section

Time required to complete entire

order

Interpreting the Output: Why are the capacity utilizations at 100% for ACI and MA and not Solder?

• ACI: With its shorter CT (relative to the MA operation) the ACI process continues to push all of its completed units to the buffer/queue in front of the MA operation.

• MA: In this instance the MA operation is the bottleneck.

• Solder: Must wait for units from the MA operation due to MA’s greater CT


Analysis Worksheet – Results Section

54.05%

ACI MA Solder RTY

68.46% 71.94% 69.20% 34.08%

$65.73 $75.06 $59.25

6.15 11.31 7.34

Raw Materials Process Scrap* Total

$240.50 $255.58 $2.55 $498.63

11.35

6.75

* WIP's in the end are considered as Scrap.

** Std Dev of End Time Differences between Two Consecutive Good Units.

Standard Deviation**

Material Yield

By Process

Yield

CycleTime/Good Unit

ProcessCost/Good Unit

Overall

CycleTime/Good Unit

Cost/Good Unit

RESULTS

Calculations for each of the above metrics are covered on following slides


Results Calculations - Yields

%5.68539

369

ACIby processed units total

ACIby produced units good totalYield ACI

34.1% 69.2% * 71.9%* 68.5%

YieldSolder *YieldMA *Yield ACI (RTY) Yield Throughput Rolled

Similar calculations will determine MA and Solder yields

%05.54370

200

used (RM) Material Raw

produced units total Yield Material


Results Calculations - Process

73.65$369

00.45$*539

units good total

cost/unit*processed unitstot

UnitGood

Cost Process

15.6369

%100*4.2270

units good total

nutilizatio cap.*CT total

UnitGood

Time Cycle

ForACIProcess

35.11200

4.2270

goods) (fin.Solder in units Good

CT Total UnitGood / CT


Results Calculations - Overall Costs

50.240$200

00.130$*370

goods) (fin.solder in units Good

cost/unit RM * UsedRMunit goodcost / RM

58.255$200

)41$*28954$*27845$*539(

solderin units good total

proceach

1cost process * processed units

unit Cost/good Process

i

55.2$

200

3$*)00(3$*)1690(3$*)10(

solderin units good total

proceach

1cost scrap* WIP scrap. units

unit Cost/good Scrap

i

63.498$55.2$58.255$50.240$ UnitGoodCost / Total


Hidden Cost Worksheet - Yields

ACI MA Solder

100% 54% 100%

69% 38% 70%

68% 72% 69%

47% 51% 48%1st Quality 1st Time/Thruput

1st Quality 1st Time/Input

1st Quality/Thruput

1st Quality/Input

VARIOUS YIELDS

Yield Definitions:

1. 1st Quality / Input: How many good units were made by the process given the amount of raw

material or good units supplied by the prior process?

2. 1st Quality – 1st Time / Input: How many good units were processed on their first pass through the

operation?

3. 1st Quality / Throughput: Accounts for the impact of reworked units by looking at the total number of

units processed by the operation – versus the quantity of raw material or units delivered to the

process.

4. 1st Quality – 1st Time / Throughput: Of the total number of units processed by the operation, what

percentage were produced defect-free on their first pass through the operation?


Hidden Costs – Yield Calculations

370

ACI

539

Total 369

First 256

Recycled 113

170

0

1

100%

ACI

RM $130.00

Process $45.00

Scrap $3.00

2270.40

Cost/Unit

Good Units

Work In Process (WIP)

Units Recycled

Units Scrapped

Capacity Utilization

Total Cycle Time

Raw Materials (RM) Used

Production Records

Units Processed

Cost Parameters

INPUT

ACI MA Solder

100% 54% 100%

69% 38% 70%

68% 72% 69%



1st Quality/Thruput

1st Quality/Input

VARIOUS YIELDS

100%) to(rounded %73.99370

369

process)last from units (goodor used) (RM

processby made units good total

Input

quality1st

For the MA and Solder operations, the denominator

is the total good units processed from the prior step – in this case, MA would use “369” from the ACI column.

Analysis Worksheet

Hidden Cost Worksheet


%2.69370

256

process)last from units (goodor used) (RM

operationby made units goodrun 1st

Input

1st time -quality 1st


370

ACI

539

Total 369

First 256

Recycled 113

170

0

1

100%

ACI

RM $130.00

Process $45.00

Scrap $3.00

2270.40

Cost/Unit

Good Units


Units Recycled

Units Scrapped


Total Cycle Time


Production Records

Units Processed

Cost Parameters

INPUT

ACI MA Solder

100% 54% 100%

69% 38% 70%

68% 72% 69%



1st Quality/Thruput

1st Quality/Input

VARIOUS YIELDS


%4.68539

369

processed units total

operationby made units good total

Throughput

quality1st


370

ACI

539

Total 369

First 256

Recycled 113

170

0

1

100%

ACI

RM $130.00

Process $45.00

Scrap $3.00

2270.40

Cost/Unit

Good Units


Units Recycled

Units Scrapped


Total Cycle Time


Production Records

Units Processed

Cost Parameters

INPUT

ACI MA Solder

100% 54% 100%

69% 38% 70%

68% 72% 69%



1st Quality/Thruput

1st Quality/Input

VARIOUS YIELDS


%5.47539

256

processed units total

operationby made units goodrun 1st

Throughput

1st time -quality 1st


370

ACI

539

Total 369

First 256

Recycled 113

170

0

1

100%

ACI

RM $130.00

Process $45.00

Scrap $3.00

2270.40

Cost/Unit

Good Units


Units Recycled

Units Scrapped


Total Cycle Time


Production Records

Units Processed

Cost Parameters

INPUT

ACI MA Solder

100% 54% 100%

69% 38% 70%

68% 72% 69%



1st Quality/Thruput

1st Quality/Input

VARIOUS YIELDS


Hidden Costs – Factory Calculations

With defects Without defectsDifference

(Hidden factory cost)% Reduction

1.66 1 0.66 0.40

498.63 300.53 198.10 0.40

11.35 6.84 4.51 0.40

Units

In order to produce 1 unit that has no defect

Cycle time

Cost

HIDDEN FACTORY COSTS

1.6592 0.3408)-(11

RTY)-(11

ratedefect 1 units

From earlier calculations

52.300$1.66

$498.63

unitdefect no produce tounits of #

defectscost w/

defect cost w/out

84.61.66

11.35

unitdefect no produce tounits of #

defects w/ CT

defects w/out CT


Defect WorksheetThe Defect worksheet presents the final results by defect-type for the latest simulation run.

NOTE: A defective PCB may have more than one type of defect. Furthermore, a defective PCB may also have more than one occurrence of the same defect type.

In this case:

ACI

Y1 Y2 Y3 Y4 Y5 Y6Good 511 539 486 484 491 539

Rework 28 0 53 55 48 0Scrap 0 0 0 0 0 0

29 0 53 57 52 0 Y1: Epoxy Contamination Y2: Tuner Misalignment Y3: Missing/Wrong Parts Y4: Length of Leads Y5: Bad Assembly Y6: Chip Skew

MA

Y1 Y2 Y3 Y4 Y5 Y6Good 251 278 251 278 263 261

Rework 27 0 27 0 15 17Scrap 0 0 0 0 0 0

31 0 28 0 15 17 Y1: Reversed Parts Y2: Wrong Parts Y3: Leg-Outs Y4: Shortened Leads Y5: Incorrect Rework Y6: Missing Parts

Solder

Y1 Y2 Y3 Y4 Y5 Y6Good 261 275 257 289 283 262

Rework 28 14 32 0 6 27Scrap 0 0 0 0 0 0

29 14 32 0 6 29 Y1: Missing Solder Y2: Glue Contamination Y3: Solder Bridge Y4: Insufficient Solder Y5: Solder Composition Y6: Others

Defectives

Defects

Quality

Defectives

Defects

Quality

Defectives

Defects

Quality

TYPE of DEFECTS and FREQUENCIES

• The ACI operation processed 539 PCB’s. (This total will agree with the “Units Processed” field on the Analysis worksheet)

• For the ACI operation, 511 units were “good” or non-defective with respect to defect type “Y1”. The remaining 28 units had a total of 29 Y1 defects (i.e., one PCB had two Y1 defects).

• Similarly, of the 278 units processed by the MA operation, there were 27 defective PCB’s that required rework due to defect type Y1 (note there were 31 total type Y1 defects)


Chart Worksheets

The following control charts are presented for completeness in covering the Excel simulation data file.

Discussion on the use and application of control charts is beyond the scope of this presentation. There are many excellent sources of information on this subject; “Statistical Quality Control, Strategies and Tools for Continual Improvement” by Johannes Ledolter and Claude W. Burrill is recommended, as is “Statistical Quality Control” by Eugene L. Grant and Richard S. Leavenworth.

ACI Control Charts

Individual Chart: Cycle Time

4.00

4.20

4.40

4.60

4.80

5.00

5.20

0 10 20 30 40 50 60 70 80 90

Process Unit

Ho

urs


Chart Worksheets

Moving Range Chart: Cycle Time

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 10 20 30 40 50 60 70 80 90

Process Unit

Ho

urs


Chart Worksheets

Defective Rate(P)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 1 2 3 4 5 6 7 8

P


CumData Worksheet This worksheet presents the same basic information as the Data

worksheet, but with a few significant differences:

The data on this worksheet is maintained, unless otherwise intentionally cleared, during multiple simulation runs. This allows data to be captured and saved during a series of DOE simulation runs.

This worksheet contains subgroup data. The subgroup size defaults to 10 units and can be manually changed in the Extend simulation.

The cycle time for each processed unit is reported – versus the start and stop times in the Data worksheet

The data contained in the component measure(ACI-CM-Y#) and component index (ACI-CI-Y#) columns are identical to the Data worksheet.


CumData Worksheet SectionsThe data on this worksheet is presented in a similar format to that on the Data worksheet…

… A section containing the number of defects by defect type for each operation…

… A section indicating the quality index (need for rework or scrap) by each defect type…

… And a section containing the number of defective units per defined subgroup size due to each defect type .


CumData Worksheet - Subgroups An inspection of columns “B” through “O” will show

the data is identical to that on the Data worksheet. The subgroup size, which is defined in the Extend

simulation, was left at the default size of 10. The subgroup data (columns “Q” through “W”) for the

final subgroup will not be completed any time the simulation run is either:

a) Stopped prior to producing a complete subgroup or,

b) The defined number of units are some fraction of the subgroup (e.g., a run size of 78 with a subgroup size of 10)


CumData Worksheet - Subgroups

• NOD = Number of Defectives

• The sum of the number of defective units for the subgroup (column “C”) is shown in column “Q” (ACI-TQ-NOD)

• Likewise, the totals for the number of defective units per defect type are shown in columns “R” through “W”

• As on the Data worksheet, multiple defect types on a single unit may contribute to the unit being identified as defective (e.g., second unit in the subgroup, Row 13)


Design of Experiments (DOE) The CumData worksheet contains all of the

data needed to analyze the results of a DOE To conduct a DOE you will need to set the

“Number of Units to Produce” button to “1”

Do not click the “Send Command” button – this will erase all CumData worksheet information for the prior runs


DOE – ACI Output

This screenshot shows the results of ten consecutive runs. Each simulation run is set to terminate after processing one unit, regardless of whether the unit was good, required reworked, or was scrapped. Each simulation run, as in a DOE, had different factor settings.

• The “run number” is captured in column “A” – this number will correspond with the run order assigned to the DOE in Minitab.

• In performing a DOE, each simulation run processes a “new” unit. Thus, one cannot deduce how many process cycles it took to produce a good unit by examining the ACI-TQI data.

• Columns A through W should be copied into Minitab to analyze the DOE results (Similar steps will be taken to analyze the Manual Assembly and Solder processes).

Documents

Six Sigma Simulation Data Definitions and Worksheet Descriptions