What is MSA?

 Full form of MSA is Measurement Systems Analysis. MSA is a process to validate the measurement system of an organisation. It indicates error in measurement system. 

The main aim of MSA is to assure that measurement system delivers reliable results with repeatability and reproducibility (R&R).

It is important to get the right data for the each part of the product, if there is an error gauge, then, we will not able to get correct data which in turn give wrong interpretation about the data and wrong size product will reach to the customer, so it is important to have each gauge R&R at regular frequency.

MSA is define mathematically method of determining the amount of variation that exists within a measurement process. Variation in the measurement process can directly contribute to overall measurement system. MSA is used to certify the measurement system for use by evaluating the system’s accuracy, precision and stability.

It is one of the core tool of IATF16949. Other core tool of IATF16949 are:

1. APQP: Advance Product Quality Planning
2. PPAP: Production Part Approval Planning
3. FMEA: Failure Mode and Effects Analysis
4. SPC : Statistical Process Control

You can read above topic by clicking on them.

Before we go ahead and understand more about MSA we should understand about measurement system, it consist of mainly two things one the instrument in which product is checked and second one is the operator or workman who is checking the product with the gauge or instrument. Two more things can be considered in measurement system that is SOP (Standard operating procedure) which tell us about how to check the product, and sampling plan can be define in SOP and second the environment in which product is checked, some time there is difference in the temperatures of reference master has compared to actual product to be check (this make great error in the final product). These four factors involved in system and effect the measurement system.

Four part of measurement system:

1. Gauges and standard lab
2. Operator or workman (Man power)
3. SOP (Standard operating procedure)
4. Environment.

These above mentioned factors are the contributor for variation in measurement system. To get the right measurement we will have to be very particular about these factors, In this article we mainly discuss first two factor. 

How to Perform MSA:

As we are now able to understand what is MSA, why we have to perform MSA, now it is important to understand how to perform MSA.

To perform MSA first of all we have to collect data from different samples, locations and  different time, analyse these data and evaluate the stability of the system or any variation in measurement system.

Here data is termed as the value taken during measurement of the product. For this data could be attribute data or variable data. Attribute data have specific values, where as  variable can have an infinite number of values. 

To perform MSA we have to do Gauge R&R (Gauge Repeatability and Reproducibility). 

1. Initially we have to select a gauge for which MSA have to perform.
2. Then select three or four operators who usually perform on or operate that gauge.
3. Now collect Samples from 10 different locations or time.
4. Ask all selected operators to check all  sample on same gauge and note reading on paper.
5. Repeat step 4 three times with same sample but sample should be randomly select.
6. Now calculate the average of readings differently for each operators.
7. For each sample, calculate the difference of each operator’s averages, average range and the range of measurements.
8. Repeatability is calculated to determine the variation in Gauge and reproducibility is calculated to determine variation introduce or done by operator during checking of parts on gauge.
9. Now calculate total variation in part and variation percentage.

After calculation, ir variation percentage is less than 10, then gauge is OK to use and all Operators/inspectors are also  able to use gauge efficiently, and if percentage is more than 10, then either gauge is creating problem or operators/inspectors are not familiar to use the gauge.

For gauge R&R is done for the gauge that need human intervention and if gauge is run by machine or gauge is installed in machine where human intervention is almost zero, then MSA for this gauge is done by gauge stability test or gauge reliability.

For gauge reliability test reference master reading is taken per hour for a day, i.e. 20 - 24 reading to be take and then variation is to check. Similarly gauge R&R if variation is less then 10% then there is no issue and gauge ready to use in daily process but if variation is more than 10% then gauge calibration or some correction is required.

MSA is usually done for new gauge in the system or new process add up in system. Some time is also done on the requirement of customer or there is some fault observed in reading.