Measurement system analysis definition
MSA is defined as an experimental and mathematical method of determining the amount of variation that exists within a measurement process. Variation in the measurement process can directly contribute to our overall process variability. msa measurement system is used to certify the measurement system for use by evaluating the system’s accuracy, precision and stability.
A Measurement systems analysis (MSA) is a thorough assessment of a measurement process, and typically includes a specially designed Experiment that seeks to identify the components of variation in that measurement process.
The Purpose of Measurement System Analysis is to qualify a measurement system for use by quantifying its accuracy, precision, and stability.
Measurement Systems Analysis Fundamentals
- Determine the number of appraisers, number of sample parts, and the number of repeat readings. Larger numbers of parts and repeat readings give results with a higher confidence level, but the numbers should be balanced against the time, cost, and disruption involved.
- Use appraisers who normally perform the measurement and who are familiar with the equipment and procedures.
- Make sure there is a set, documented measurement procedure that is followed by all appraisers.
- Select the sample parts to represent the entire process spread. This is a critical point. If the process spread is not fully represented, the degree of measurement error may be overstated.
- If applicable, mark the exact measurement location on each part to minimize the impact of within-part variation (e.g. out-of-round).
- Ensure that the measurement device has adequate discrimination/resolution, as discussed in the Requirements
- Parts should be numbered, and the measurements should be taken in random order so that the appraisers do not know the number assigned to each part or any previous measurement value for that part. A third party should record the measurements, the appraiser, the trial number, and the number for each part on a table.