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Six Sigma Simulation Data Definitions and Worksheet Descriptions

Six Sigma Simulation Data Definitions and Worksheet Descriptions. 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

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Six Sigma Simulation Data Definitions and Worksheet Descriptions

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  1. Six Sigma Simulation Data Definitions and Worksheet Descriptions

  2. 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) Six Sigma Data Definitions

  3. Worksheets The 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 Data Definitions

  4. Six Sigma Simulation Screenshot Six Sigma Data Definitions

  5. Automatic Component Insertion Y1: Epoxy Contamination Y2: Tuner Misalignment Y3: Missing/Wrong Parts Y4: Lead Length Y5: Bad Assembly Y6: Chip Skew Manual Assembly Y1: Reversed Parts Y2: Wrong Parts Y3: Leg-Outs Y4: Shortened Leads Y5: Incorrect Rework Y6: Missing Parts Defect Definitions Solder Y1: Missing Solder Y2: Glue Contamination Y3: Solder Bridge Y4: Insufficient Solder Y5: Solder Composition Y6: Others Six Sigma Data Definitions

  6. 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. Six Sigma Data Definitions

  7. Data Worksheet Screenshot The Data worksheet contains similar sections for the remaining two operations – Manual Assembly (MA) and Solder. Six Sigma Data Definitions

  8. Pull material from queue No PCB acceptable? Parts at queue? Parts at mfg station (new or rework)? Start Manufacture next PCB Send PCB to next operation or ship finished product Yes Yes Yes No No PCB scrap? Pull parts from raw material Scrap part Yes No Send PCB back to mfg process for rework Material Flow Process Six Sigma Data Definitions

  9. Data Worksheet • 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. Raw Material Shipment Example Six Sigma Data Definitions

  10. Data Worksheet CumData 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). Six Sigma Data Definitions

  11. Data Worksheet - Quality Index There are three main, identical sections for each operation containing information on process quality: • 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”. • 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). • Component Index – A qualitative quality measurement. The six columns provide the results for each of the defect types. Six Sigma Data Definitions

  12. 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). Total Index Results: The PCB must be reworked (Index = 2). Data Worksheet - Interpretation Six Sigma Data Definitions

  13. Data Worksheet - Interpretation • Material Flow Example: • 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. • 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. • On the third pass through the process, these defects are corrected, however, a Y5 (bad assembly) defect type is caught at inspection. • Finally, on the fourth pass through the system, the PCB passed quality inspection. Six Sigma Data Definitions

  14. Data Worksheet - Interpretation 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. Data Worksheet =COUNTIF(entire Y6 column,2) =SUM(entire Y6 column) Defect Worksheet Six Sigma Data Definitions

  15. Analysis Worksheet This 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 Six Sigma Data Definitions

  16. Analysis Worksheet – Input Section RM shipped prior to completing order (in this case 200) PCB’s requiring no rework 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. 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. 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 Six Sigma Data Definitions

  17. Data pulled from simulation The cost parameters are fixed Analysis Worksheet – Input Section 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 Time required to complete entire order Six Sigma Data Definitions

  18. Analysis Worksheet – Results Section Calculations for each of the above metrics are covered on following slides Six Sigma Data Definitions

  19. Results Calculations - Yields Similar calculations will determine MA and Solder yields Six Sigma Data Definitions

  20. Results Calculations - Process For ACI Process Six Sigma Data Definitions

  21. Results Calculations - Overall Costs Six Sigma Data Definitions

  22. Hidden Cost Worksheet - Yields • Yield Definitions: • 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? • 1st Quality – 1st Time / Input: How many good units were processed on their first pass through the operation? • 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. • 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? Six Sigma Data Definitions

  23. Hidden Costs – Yield Calculations 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. Hidden Cost Worksheet Analysis Worksheet Six Sigma Data Definitions

  24. Hidden Costs – Yield Calculations Six Sigma Data Definitions

  25. Hidden Costs – Yield Calculations Six Sigma Data Definitions

  26. Hidden Costs – Yield Calculations Six Sigma Data Definitions

  27. Hidden Costs – Factory Calculations From earlier calculations Six Sigma Data Definitions

  28. Defect Worksheet The 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: • 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) Six Sigma Data Definitions

  29. 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. Six Sigma Data Definitions

  30. Chart Worksheets Six Sigma Data Definitions

  31. Chart Worksheets Six Sigma Data Definitions

  32. 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. Six Sigma Data Definitions

  33. CumData Worksheet Sections The 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 . Six Sigma Data Definitions

  34. 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: • Stopped prior to producing a complete subgroup or, • The defined number of units are some fraction of the subgroup (e.g., a run size of 78 with a subgroup size of 10) Six Sigma Data Definitions

  35. 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) Six Sigma Data Definitions

  36. 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 Six Sigma Data Definitions

  37. 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). Six Sigma Data Definitions

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