Presentation is loading. Please wait.

Presentation is loading. Please wait.

MSA Example: Attribute or Categorical Data. All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 2.PPT MSA Operational Definitions.

Similar presentations


Presentation on theme: "MSA Example: Attribute or Categorical Data. All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 2.PPT MSA Operational Definitions."— Presentation transcript:

1 MSA Example: Attribute or Categorical Data

2 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 2.PPT MSA Operational Definitions Accuracy: Overall agreement of the measured value with the true value (which may be an expert value). Bias plus precision. Attribute Data: Discrete qualitative data. Attribute Measurement System: Compares parts to a specific set of criteria and accepts the item if the criteria are satisfied. Bias: A systematic difference from the true value. Revealed in the differences in averages from the true value. Precision: Variation in the measurement process. R&R: Repeatability and Reproducibility. Two elements of precision. Repeatability: The variation observed when the same operator measures the same item repeatedly with the same device. Reproducibility: The variation observed when different operators measure the same parts using the same device, sometimes it can be the same operator using different devices.

3 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 3.PPT Is the variation (spread) of the measurement system too large to study the current level of process variation? += (Observed Variability) Total Variability Product Variability Process Variability Variation in the measurement process The Fundamental MSA Question

4 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 4.PPT True Value or Standard Bias Observed Average Possible Causes of Bias Sensor not properly calibrated Improper use of sensor Unclear procedures Human limitations Bias

5 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 5.PPT Repeatability Possible Causes of Poor Repeatability Equipment Gage instrument needs maintenance The gage needs to be more rigid People Environmental conditions (lighting, noise) Physical conditions (eyesight) Repeatability

6 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 6.PPT Reproducibility Mean of the measurements of Operator B Mean of the measurements of Operator A Possible Causes of Poor Reproducibility Measurement procedure is not clear Operator is not properly trained in using and reading gage Operational Definitions not established Reproducibility

7 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 7.PPT Discrete qualitative data Go/no-go basis; or limited data categories Compares parts to specific criteria for accept/not accept or to be placed in category Must screen for effectiveness to discern good parts from bad At least two appraisers and two trials each If available, have Quality Master rate parts first Attribute Measurement Systems Study

8 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 8.PPT Attribute MSA Study Attribute MSA Example Appraiser A Appraiser B Master1212 1GGGGG 2GGGGG 3GNGGGG 4NGNGNGNGNG 5GGGGG 6GGGNGG 7NGNGNGGNG 8NGNGNGGG 9GGGGG 10GGGGG 11GGGGG 12GGGGG 13GGNGGG 14GGGGG 15NGGGGG 16GGGGG 17GGGGG 18GGGGG 19GGGGG 20NGGGGG G = Good NG = Not Good

9 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 9.PPT Challenges of Continuous Process MSA MSA study is an experiment Requires two or more trials for calculating Repeatability Needs a way to present the inspection units to the appraiser multiple times Is not possible within the continuous process

10 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 10.PPT Case Example: Visual Inspection of Glass Catwalk Glass Inspector Cutter Packers

11 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 11.PPT Case Example: Challenges to Overcome Bias to the standard could be evaluated on-line. Repeatability and Reproducibility (R & R) could not be evaluated on-line. A method had to be devised to allow the inspectors to view the same pieces of glass repeatedly. The solution was an off-line conveyor which simulated the on-line condition as closely as possible.

12 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 12.PPT 20 pieces of glass from the process that included both good and bad samples were selected. A team of people well versed in the quality standard classified each piece of glass as either pass or fail. All regular inspectors independently evaluated each piece twice (in random order). The inspectors used a log sheet to record the data. Minitab ® was used to analyze the data. Case Example: Attribute MSA Method Employed

13 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 13.PPT Excerpt of full data for 20 inspectors Case Example: Attribute MSA Study Data

14 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 14.PPT Case Example: Attribute MSA Study Results

15 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 15.PPT Case Example: Attribute MSA Study Results (continued)

16 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 16.PPT Case Example: Attribute MSA Study Results (continued)

17 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 17.PPT Case Example: Attribute MSA Study Results (continued)

18 All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 18.PPT What could have caused the poor agreement? What was done to improve consistency? Case Example: Attribute MSA Study Conclusions


Download ppt "MSA Example: Attribute or Categorical Data. All Rights Reserved, Juran Institute, Inc. MSA for Continuous Processes 2.PPT MSA Operational Definitions."

Similar presentations


Ads by Google