MSA: What is Measurement System Analysis ?

MSA is defined as an experimental and mathematical method for determining the amount of variation that exists within a measurement process. Variation in the measurement process can contribute directly to our overall process variability.

MSA is used to certify measurement systems for use by evaluating the accuracy, precision and stability of the system.

Measurement System Analysis (MSA) is the in-depth evaluation of a measurement process, and usually involves a specially designed experiment that seeks to identify the components of variation in that measurement process.

Just as the processes that manufacture a product can vary, the process for measuring and obtaining data can vary and produce erroneous results. Measurement System Analysis The entire process of obtaining measurements (typically quality analysis) and the decisions made about a product or process to ensure the integrity of the test method, measurement equipment, and data used to obtain the analysis Evaluates to understand the implications of measurement error.

The MSA is an important element of the Six Sigma methodology and other Quality Management Systems.

According to AIAG (2002), a general rule of thumb for measurement system acceptability is:

• An error under 10 percent is acceptable.
• 10 percent to 30 percent error indicates that the system is acceptable, depending on the criticality of the application, cost of the measurement equipment, cost of repair, and other factors.
• An error greater than 30 percent is considered unacceptable, and you should improve the measurement system. The AIAG also states that the number of different categories into which the measurement system is divided must be greater than or equal to 5.
• In addition to the percentage error and the number of different ranges, you should also review the graphical analysis over time to decide on the acceptability of the measurement system.

Factors affecting an MSA process

May include the following factors:

• Equipment: Measuring instruments, calibration, fixing.
• People: operators, training, education, skills, care.
• Process: Test method, specification.
• Samples: Materials, items to be tested (sometimes called "parts"), sampling plan, sample preparation.
• Environment: Temperature, humidity, conditioning, pre-conditioning. Management: training programs, metrology systems, people support, quality management system support.

Why do Measurement System Analysis (MSA) {Why Perform Measurement System Analysis (MSA)}?

An effective MSA process can help ensure that the data being collected is accurate and that the data collection method is appropriate for the process. Good reliable data can prevent wasted time, labor and scrap in a manufacturing process. A major manufacturing company began receiving calls from several of its customers to receive non-compliant materials at their facility sites. The parts were not properly snapping together to form a uniform surface or would not lock into place.

The process was audited and found to be manufacturing parts. The operator was following the inspection plan and was using the gauge assigned for the inspection. The problem was that the gang did not have sufficient resolution to locate the non-conforming parts. An ineffective measurement system can allow bad parts to be accepted and good parts to be rejected, resulting in unsatisfied customers and excessive scrap. The MSA could have prevented the problem and assured that accurate useful data was being collected.

MSA variable

Objective of Measurement System Analysis (MSA): Confirm that the measurement system used to collect the data is valid. The first goal is:

• Process variation
• Appraiser variation and
• Total measurement system variation
• Second, minimize measurement system variation and its effect on total variation so that the amount of process variation is understood as accurately as possible.

The following components of measurement capability need to be studied and quantified before establishing process capability and making decisions from the data-

• ACCURACY / BIAS
• RESOLUTION / DISCRIMINATION LINEARITY STABILITY
• REPEATABILITY and REPRODUCIBILITY

The MSA is often a very time consuming component of the project and can slow down the team's quick progress through the process. Continue to focus on the low hanging fruit that can be "sustained" and work rigorously through the MSA process. Much of this work can be done by the GB/BB outside of team meetings.