Surface Texture Gage study in the qs-stat Measurement System Analysis Module

Transcription

1 study in the qs-stat Measurement System Analysis Module Q-DAS Library Living Documentation Last edited: 11/22/2004 Version: EB C:\Documents and Settings\Ellen Fassbeck\My Documents \My Temp Files\GMPT\TC\GMPT Surface texture MSA in qs- Stat_eb.doc

2 Table of Contents 1 PROCEDURE CALIBRATION STUDY PREPARATORY STUDY TYPE 2 STUDY REQUIRED SETUP IN QS-STAT EXAMPLE FOR A SURFACE TEXTURE STUDY IN QS-STAT CALIBRATION STUDY PREPARATORY STUDY TYPE-2 ANOVA GR&R STUDY SURFACE TEXTURE STUDY IN QS-STAT

3 Surface Texture Gage 1 Procedure 1.1 Calibration study The system must be checked for proper function and calibrated before starting the Study, using a 3 patch precision reference standard and where required an appropriate calibration fixture. Verify the system by checking 5 times on each patch and calculate the average of the readings. This average must be within 5% of the known calibrated value. Calibration to the first patch sets gain, the second patch verifies linearity and the third patch validates the stylus. Completion of these tests shall demonstrate the instruments Accuracy and Linearity. (quote from SP-Q-EMS-GLOBAL, chapter Surface texture gages) 1.2 Preparatory study A preparatory study for each to be evaluated feature is conducted. Features are for example: Ra, Rmax, Rz, Wt, etc. Surface Texture gages present a unique challenge to measurement systems analysis in that the variation in the parts may be large in comparison to the specification tolerance. Therefore, a preparatory study must be conducted to quantify the piece variation. Select a part that is a representative of the process to be analyzed by the instrument. Measure 25 traces in one position (Do not move part or instrument). From these trace results, calculate the instrument standard deviation s i. Repeat step 2 with a minor incremental movement of the stylus relative to the part, each time perpendicular to the lay. Measure 25 traces. From these trace results, calculate the total deviation s t. Calculate standard deviation within part s s (quote from SP-Q-EMS-GLOBAL, chapter Surface texture gages) The standard deviation surface Ss for each feature is calculated with: s s = s 2 2 t - s i 3

4 1.3 Type 2 study Then a type 2 study is conducted. As it is impossible to eliminate the surface variation during the study, the calculated Surface Variation SV is subtracted from the normal R&R result. The resulting Surface Variation is calculated out of the R&R value with RR=(EV 2 +AV 2 +IA 2 -SV 2 ) 0.5 With SV=5.15*Ss (SV=Surface Variation; variation range of 99%) and EV (Equipment Variation), AV (Appraiser Variation) and IA (InterAction) calculated according the ANOVA method. Reference figure for the %G&R is the tolerance of each feature Requirements are Measurement system capable: %R&R </= 20% Measurement System conditionally capable: 20% </= %R&R </= 30% 4

5 2 Required Setup in qs-stat 1. Switch to the Measurement System Analysis module 2. call up or create an evaluation strategy under OPTIONS/CONFIGURATION OF EVALUATION which includes the following three study types: SURFACES CALIBRATION, SURFACES -PREPARATORY and TYPE 2 STUDY 5

6 3. settings for SURFACES -CALIBRATION: 6

7 4. settings for SURFACES -PREPARATORY 7

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9 5. settings TYPE 2 STUDY 9

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11 The so configured evaluation strategy needs to be selected before starting a new surface texture study file. 11

12 Surface Texture Gage 3 Example for a Surface Texture Study in qs-stat 3.1 Calibration Study CALIBRATION STUDY DATA FOR Ra ONLY Trace # Calibration Patch Linearity Patch Stylus Check Patch* Average Certified Patch Value Certified Value +5% Certified Value -5% Is average within Certified Value +/- 5%?, YES YES YES *Note: If using a 5 micron radius stylus on a PDR-6 Precision, Reference Standard (from Precision Devices, Inc.) Stylus Check patch, add 0.04 micron to the certified patch value. This correction applies to only the Stylus Check patch.,,,,,,,,,, If the average of the measurements are within +/-5% of the Certified Patch Value, proceed with the preparatory study. Remark: the Calibration study results in this table were calculated in Excel. 12

13 3.2 Preparatory Study Example data for 2 features: Rz and Wt 25 traces in 1 position 25 traces with repositioning after each Trace # Rz [mm] Wt [mm] Trace # Rz [mm] Wt [mm] S i = S t =

14 3.3 TYPE-2 ANOVA GR&R STUDY for 5 parts, 2 operators and 3 trials Feature 1: Rz [mm] Operator A Operator A Operator A Operator B Operator B Operator B Piece # Trial 1 Trial 2 Trial 3 Trial 1 Trial 2 Trial Feature 2: Wt [mm] Operator A Operator A Operator A Operator B Operator B Operator B Piece # Trial 1 Trial 2 Trial 3 Trial 1 Trial 2 Trial

15 3.4 Surface Texture Study in qs-stat 1. select the menu function FILE / FILE NEW 2. Pick 1 characteristics for the Surfaces Overall and, here, 2 characteristics for each the Surfaces Preparatory and Type 2 study (Rz and Wt): 15

16 3. A blank parts and characteristics mask appear on the screen. First, the parts mask should be filled out. 4. After the parts data is entered, the parts mask can be closed. Only the characteristics mask is left on the screen and can be filled out. The active characteristic should be the first one, the Overall - : 16

17 5. If you want to perform a calibration study in addition to the preparatory and type 2 study, please open up a Parts-/ characteristics list from the Summary menu item 6. Insert a new characteristic for the calibration study in front of the preparatory study with a right mouse-click 17

18 7. Hit the Execute evaluation icon, close the Parts-/ characteristics list and go back to the Characteristics Mask. In order to get a better overview over the available characteristics, a Characteristics List can also be shown in the characteristics mask. To do so, make sure the characteristics mask is active and click on the Info - button Check the box for Characteristic list 8. The list in the can be used to navigate through the different characteristics. To fill out the information for the Calibration study, click on the second characteristi c in the list. A blank characteristic mask should come up. Double check the setting under type whether it displays Surfaces - Calibration and fille out the required information. Set the number of parts to 3 the number of reference measureme nts to 1 and the number of repetitions to 5. Confirm each entry with the Enter key. The Unit for all characteristics and values should be mm. 18

19 9. Rz Preparatory study. Double check the settings for evaluation type whether it is set to Preparatory study. Set the Number of marks and number of Repetitions to 25. Enter Characteristic number, description, Nominal and Upper and lower Specification limits and gage resolution. For a Surface Texture Study, it is very important to set the Measured Quantity to Rz. The information of the measured quantity is used to connect the preparatory study and the type 2 study characteristics. 10. Switch the characteristic and fill out the mask for the Rz Type 2 study. The information for the measured quantity needs to be set the same as it is set in the associated preparatory study. 19

20 11. Switch to the Characteristics Mask for the Wt characteristic and fill out the information for the preparatory and the Type 2 study accordingly. 12. Close the Characteristics Mask 20

21 13. Enter or Copy and paste the Measurement Values for each characteristic into the Values Mask (unit: mm) 14. Close the Values Mask. 15. Define the Characteristics Structure: The characteristics for the Overall needs to be set as an superimpos ed Characteristic. To do this, please open up a Parts- /Characteristics list. 21

22 16. Drag and drop all other characteristics under the overall evaluation characteristic: if a characteristic for the calibration study was added, this characteristic needs to b dragged and dropped under the overall evaluation characteristic as well so that all characteristics are sub-ordinate to the overall evaluation characteristic. 17. The characteristics structure should look like this: 18. Close the Part / characteristics list and Execute the with the Calculator button. 22

23 19. Bring up the Charts, for example the Form Sheet 3 for the first Overall result characteristic. It will only display a Smiley face if all studies have been passed. A question mark appears, if one or more characteristics are conditionally capable and all others are capable and a frowny face will be displayed, if one characteristic did not pass. 20. Switch to the next characteristic and bring up the Charts, for example the Value Chart Individuals, the Individual Values Chart (under Numerics ) and the Form 3 for the Calibration study The displayed results in the Form 3 refer to the maximum deviation of all three calibration patches. If one calibration patch fails, the whole calibration study is failed. 23

24 21. The Value Chart Individuals and the Form 3 for the Preparatory study: The numerical values Si, St and the Standard deviation Surface Ss have been calculated and are available on the Form 3. 24

25 22. Switch to the Type 2 studies. The Surface Variation SV has been calculated using the Ss from the associated preparatory study. The GR&R value is calculated with RR=(EV 2 +AV 2 +IA 2 -SV 2 )