Diagnosis of IATF 16949:2016 clause – 7.1.5.1.1 Measurement System Analysis (MSA)

Posted on: December 23rd, 2017  /  By:  /  Posted in: #QUALiTYViVA, IATF, IATF16949, Measurement System Analysis, MSA  /  Comment: 3

Clause – 7.1.5.1.1 Measurement System Analysis

Statistical study shall be conducted to analyse the variation present in the result of each type of inspection, measurement, and test equipment system identified in the control plan. The analytical method and acceptance criteria used shall conform to those in reference manual on measurement system analysis. Other analytical method and acceptance criteria may be used if approve by the customer. Records of customer acceptance of alternative method shall be retained along with the results from alternative measurement system analysis (see Section 9.1.1.1). NOTE: Prioritization of MSA studies should focus on critical or special product or process characteristics.                                                        ———————————————– Before going for diagnosing this clause, it is interesting to learn what IATF FAQ says on MSA Question: Are MSA studies required for each instrument or devices? Answer: No. A complete statistical study on each single piece of equipment is not required. Instrument with the same characteristic (e.g. measurement range, resolution, repeatability etc) can be grouped and a sample instrument (representative of group family) can be use for statistical studies.

 DIAGNOSIS:

(A) What is Statistical study? To me, statistical study can be define as, “Science of collection of data and study of this collected data to see the trends & variation in process or in system, which help to improve the process or system”. (B) What are different sources of variation in process? The sources of variation in process are:
  1. Common cause
  2. Special cause
This causes are define by Walter A Shewhart and W. Edward Deming.
  1. Common cause:
Which shows the natural pattern and inherent to the process and are not controllable by the process operator. The common causes are also called as Natural variation. Example:
  1. Variation in temperature where testing or process are going on.
  2. Variation in humidity where testing or process are going on.
  3. Variation in raw material, such as same type of raw material procured from different sources and mixed for further process.
  4. Variation in electrical sources, because of power fluctuation.
  5. This is also true in service industry such as input data received as wrong for making purchase order.
     2. Special causes:  Special causes are also called as assignable causes. These special causes are not predictable. These causes are sporadic in nature and show the non-random pattern. When process having special causes of variation, it is found that process is not stable over time. The special causes are unpredictable and refer to any factor causing variation that affects process output. (C) What are type of inspection, measurement, and test equipment system? The type of inspection, measurement, and test equipment system first identified with respect to process involve in system and included in control plan. Types of inspection:
  1. Online inspection of product or process.
  2. Random inspection of product lot.
  3. Inspection for particular requirement, such as for surface inspection.
Type of measurement: The examples of measurements are as below: Length, volume, mass, temperature, time, pressure etc. Test equipment system: The examples of Test equipment system are as below:
  1. Ultimate Tensile testing machine.
  2. Hardness testing machine.
  3. Impact testing machine.
(D) Types of analytical method and acceptance criteria used. The analytical method and acceptance criteria used shall conform to those in reference manual on measurement system analysis. Reference manual: The list of reference manual given in standard in “ANNEX B: Bibliography – supplemental automotive” which can be follow, any one. AIAG – measurement system analysis (MSA) ANFIA – AQ 024 MSA Measurement system analysis VDA – Volume 5 “Capability of Measuring System” Analytical method and acceptance criteria: Analytical method involve two type of measurement system,
  1. Variable measurement system
  2. Attribute measurement system.
Variable measurement system comprises of determining following:
  1. Stability
  2. Bias
  3. Linearity
  4. Repeatability & Reproducibility
Acceptance criteria (Source AIAG 2010): GRR — (1) under 10 % – Generally considered to be an acceptable measurement system. (2) 10 % to 30 % May be acceptable for some application. (3) Over 30% Considered to be unacceptable. Bias and Linearity – In general statistically zero(significantly equal to zero). Attribute measurement system: The Cohen’s Kappa method use to determine level of agreement in team. Acceptance criteria(Source AIAG 2010): Kappa > 0.75 Good to excellent agreement Kappa > 0.40 Poor agreement (E) Regarding other analytical method and acceptance criteria. If any other analytical method and acceptance criteria required, same may be approved by customer and record of customer acceptance of alternative method shall be retained along with the results from alternative measurement system analysis (see Section 9.1.1.1). PS: This is my 20th and last article of this year 2017.                    ———–Wishing all a Very Happy New Year 2018.————