Measurement System Analysis
Chapter 2
Measurement System Analysis is method of finding the variation present in measurement process using mathematical techniques and experiments.Note : MSA focus only at the variation of Measurement System and not the Process.
IATF 16949 : 2016 requirements
Clause 7.1.5.1.1 Measurement System Analysis
* All business process depict variation and it is important that the measurement system deployed to collect data is capable to measuring the process variation without it adding more variation than what is true process variation.
* Observed Variation = True Process Variation + Measurement Error
* The difference between the observed variation and the true process variation should be as small as possible.
Note : Better the quality of measurement system then better will be measurements you will receive.
As a Six sigma practitioner, We must attempt :
* To identify the variation as caused by the Measurement system.
* Decide does the difference matter ?
Possible Sources of Variations
Variation shall have two sources
* The true process variation
* Variation added by Measurement system.
Observed Process Variations
1) Actual Process Variation
* Long Term Process Variation
* Short Term Process Variation
* Within Sample Variation
* Short Term Process Variation
* Within Sample Variation
2) Measurement Variation
2a. Variation due to Gage
* Accuracy ( Bias )
* Precision ( Pure error or Repeatability )
* Stability
* Linearity
2b. Variation due to Operator
* Accuracy ( Bias )
* Precision ( Pure error or Repeatability )
* Stability
* Linearity
2b. Variation due to Operator
* Reproducibility
Sources of Variations
1. Machine
2. Tooling
3. Parameter variation
4. Method Variation
5. Processing material
6. Environment
7. Measurement.
B) Process design
C) Product design ( Tolerancing )
* To be able to address the actual process variability, the variation due to the Measurement system must be identified and seperated from the process variation.
* Only once the contribution of Measurement system is known can we as practitioner conduct RCA and work at fixing the isuue if needed.
* Observed measurement must be put through Measurement system analysis to seperate True and Measurement system variation.
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