Presentation on theme: "Six Sigma Simulation Data Definitions and Worksheet Descriptions."— Presentation transcript:
Six Sigma Simulation Data Definitions and Worksheet Descriptions
Six Sigma Data Definitions2 8/6/2004 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)
Six Sigma Data Definitions3 8/6/2004 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 Definitions4 8/6/2004 Six Sigma Simulation Screenshot
Six Sigma Data Definitions6 8/6/2004 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 Definitions7 8/6/2004 Data Worksheet Screenshot The Data worksheet contains similar sections for the remaining two operations – Manual Assembly (MA) and Solder.
Six Sigma Data Definitions8 8/6/2004 Material Flow Process Parts at mfg station (new or rework)? Manufacture next PCB PCB acceptable? Scrap part Yes Send PCB to next operation or ship finished product Yes No PCB scrap? Parts at queue? No Pull material from queue Send PCB back to mfg process for rework Yes No Pull parts from raw material Start
Six Sigma Data Definitions9 8/6/2004 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 at t = 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
Six Sigma Data Definitions10 8/6/2004 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 WorksheetCumData Worksheet
Six Sigma Data Definitions11 8/6/2004 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:
Six Sigma Data Definitions12 8/6/2004 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).
Six Sigma Data Definitions13 8/6/2004 Data Worksheet - Interpretation 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.
Six Sigma Data Definitions14 8/6/2004 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 9 th PCB processed. =SUM(entire Y6 column) =COUNTIF(entire Y6 column,2) Data Worksheet Defect Worksheet
Six Sigma Data Definitions15 8/6/2004 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 Definitions16 8/6/2004 Analysis Worksheet – Input Section RM 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): 289PCB’s processed - 200Total good PCB’s 89# of PCB’s needing rework - 60Recycled PCB’s 29PCB’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.
Six Sigma Data Definitions17 8/6/2004 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
Six Sigma Data Definitions18 8/6/2004 Analysis Worksheet – Results Section Calculations for each of the above metrics are covered on following slides
Six Sigma Data Definitions19 8/6/2004 Results Calculations - Yields Similar calculations will determine MA and Solder yields
Six Sigma Data Definitions20 8/6/2004 Results Calculations - Process For ACI Process
Six Sigma Data Definitions21 8/6/2004 Results Calculations - Overall Costs
Six Sigma Data Definitions22 8/6/2004 Hidden Cost Worksheet - Yields Yield Definitions: 1.1 st 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? 2.1 st Quality – 1 st Time / Input: How many good units were processed on their first pass through the operation? 3.1 st 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 – 1 st 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 Definitions23 8/6/2004 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. Analysis Worksheet Hidden Cost Worksheet
Six Sigma Data Definitions24 8/6/2004 Hidden Costs – Yield Calculations
Six Sigma Data Definitions25 8/6/2004 Hidden Costs – Yield Calculations
Six Sigma Data Definitions26 8/6/2004 Hidden Costs – Yield Calculations
Six Sigma Data Definitions27 8/6/2004 Hidden Costs – Factory Calculations From earlier calculations
Six Sigma Data Definitions28 8/6/2004 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 Definitions29 8/6/2004 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 Definitions30 8/6/2004 Chart Worksheets
Six Sigma Data Definitions31 8/6/2004 Chart Worksheets
Six Sigma Data Definitions32 8/6/2004 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 Definitions33 8/6/2004 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 Definitions34 8/6/2004 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)
Six Sigma Data Definitions35 8/6/2004 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 Definitions36 8/6/2004 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 Definitions37 8/6/2004 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).