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articles:auditing_7.1.5 [2023/04/19 17:51] – [7 - Fitness for Purpose #1] rrandallarticles:auditing_7.1.5 [2023/07/20 20:57] (current) – [Scenarios] rrandall
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 [[articles:auditing_7.1.5#using_a_precision_micrometer_to_calibrate_gage_blocks|Scenario #6:]] Similar to the above scenario, but at a different company, you discover that the company is using a Starrett W733.1XFL-1 Wireless Electronic Micrometer to calibrate their class AS-2 Gage Block set (stainless steel, rectangular 0.010" to 2"). While the Starrett W733.1XFL-1 Micrometer Calibration certificate contains minimal information, you notice that it has a digital display with a resolution of 0.00005". To verify that the Test Accuracy Ratio (T.A.R.) is sufficient, you see that the Gage Blocks Calibration Certificate indicates an accuracy of ±10 μin." (0.00001).  [[articles:auditing_7.1.5#using_a_precision_micrometer_to_calibrate_gage_blocks|Scenario #6:]] Similar to the above scenario, but at a different company, you discover that the company is using a Starrett W733.1XFL-1 Wireless Electronic Micrometer to calibrate their class AS-2 Gage Block set (stainless steel, rectangular 0.010" to 2"). While the Starrett W733.1XFL-1 Micrometer Calibration certificate contains minimal information, you notice that it has a digital display with a resolution of 0.00005". To verify that the Test Accuracy Ratio (T.A.R.) is sufficient, you see that the Gage Blocks Calibration Certificate indicates an accuracy of ±10 μin." (0.00001). 
  
-[[articles:auditing_7.1.5#fitness_for_purpose_1|Scenario #7:]] [[ https://www.qclabels.com/Quality-Control-Labels/Limited-Calibration-Control-Stickers.aspx|{{  :articles:lpc440.jpeg?200}}]]You observed calipers being used throughout the production process, and observed that the majority of these calipers supported the “Step” dimensional measurement. Upon interviewing multiple operators, you learned that some use the “Step” feature while others do not. You took note that NONE of these calipers with a “Step” feature had a “Limited Calibration" status label… and you were told that the calipers are calibrated in-house. Upon examining the Calibration record, you noticed that the “Step” feature was not included in the calibration results. It appears that the company has not been calibrating the "Step" feature on calipers that support this dimensional measurement.+[[articles:auditing_7.1.5#relocted_weighing_scale|Scenario #7:]] You observed a weighing scale with a calibration status label. Upon examining its associated Calibration Certificate, you notice that the certificate was issued to a different address than the location where the audit is being performed. Upon asking about this discrepancy, you're informed that the weighing scale was calibrated at a different location and shipped to the current location.
  
-[[articles:auditing_7.1.5#fitness_for_purpose_2_as9100_only|Scenario #8 (AS 9100 ONLY):]] You observed micrometers being used throughout the production process, and you were told that the micrometers are calibrated "in-house". Upon Reviewing the Calibration Method, you noticed that neither the “flatness" nor “parallelism” of the anvil with the spindle had been calibrated.+[[articles:auditing_7.1.5#fitness_for_purpose_1|Scenario #8:]] [[ https://www.qclabels.com/Quality-Control-Labels/Limited-Calibration-Control-Stickers.aspx|{{  :articles:lpc440.jpeg?200}}]]You observed calipers being used throughout the production process, and observed that the majority of these calipers supported the “Step” dimensional measurement. Upon interviewing multiple operators, you learned that some use the “Step” feature while others do not. You took note that NONE of these calipers with a “Step” feature had a “Limited Calibration" status label… and you were told that the calipers are calibrated in-house. Upon examining the Calibration record, you noticed that the “Step” feature was not included in the calibration results. It appears that the company has not been calibrating the "Step" feature on calipers that support this dimensional measurement.
  
-[[articles:auditing_7.1.5#the_incomplete_register_as9100_only|Scenario #9 (AS 9100 ONLY):]] Upon reviewing the company's "//register of the monitoring and measuring equipment//", which was maintained in an Excel spreadsheet, you discovered it did not include the:+[[articles:auditing_7.1.5#fitness_for_purpose_2_as9100_only|Scenario #9 (AS 9100 ONLY):]] You observed micrometers being used throughout the production process, and you were told that the micrometers are calibrated "in-house". Upon Reviewing the Calibration Method, you noticed that neither the “flatness" nor “parallelism” of the anvil with the spindle had been calibrated. 
 + 
 +[[articles:auditing_7.1.5#the_incomplete_register_as9100_only|Scenario #10 (AS 9100 ONLY):]] Upon reviewing the company's "//register of the monitoring and measuring equipment//", which was maintained in an Excel spreadsheet, you discovered it did not include the:
   * calibration or verification method, and    * calibration or verification method, and 
   * acceptance criteria.   * acceptance criteria.
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 === Assessing the Accuracy Ratio === === Assessing the Accuracy Ratio ===
  
-An "Accuracy Ratio" is defined in [[https://www.sae.org/standards/content/as13003/|SAE AS13003, "Measurement Systems Analysis Requirements for the Aero Engine Supply Chain"]], as:+If you're unfamiliar with "accuracy ratios", read the linked article titled "[[articles:what_are_accuracy_ratios|What are Accuracy Ratios]]".
  
-<blockquote>//AS13003, sec. 2.2, "Definitions" \\  +If the calculated "accuracy ratio" is greater than 4:1, this could be justification for identifying the nonconformity as a minor.
-ACCURACY RATIO: The ratio between the total part tolerance and the total calibration tolerance of the measurement equipment.//</blockquote> +
-  +
-Machinists typically apply what they call the “[[https://rfminc.net/resource-center/metrology-tips/ten-to-one-to-ten/|Ten to One Rule]]”. This means that the measuring instrument chosen must be accurate (not just discriminate) to at least ⅒ of the tolerance being measured. For example, if you have a dimensional feature with a tolerance of 0.010", your measuring instrument must be accurate to no less than 0.001". The calculation is: \\+
  
-<WRAP centeralign>**Dimension tolerance being measured ÷ Accuracy of measuring device used = Accuracy Ratio** </WRAP> +However, if the "accuracy ratio" is below 4:1, then this could be justification for a major nonconformity.
-<WRAP clear></WRAP> +
- +
-Using another example, let's assume that you have a micrometer with an accuracy of ±0.0001". And you're using it to measure a dimensional feature with a tolerance of ±0.005". Divide 0.005 by 0.0001 to obtain your accuracy ratio. In this scenario, you'd have an accuracy ratio of 50:1. +
- +
-Management of accuracy ratio is a “risk control”. The greater the accuracy ratio, the smaller the likelihood that an Out-of-Tolerance condition will impact the feature measured. Conversely, the lower the accuracy ratio, the greater the likelihood that an Out-of-Tolerance condition will impact the feature measured (and the part). +
- +
-Calibration Labs typically apply a minimum 4:1 "Test Accuracy Ratio" (TAR) rule using a similar concept. Generally speaking, 4:1 is the lowest accuracy ratio that should be maintained in order to achieve reasonable confidence that conforming parts are being delivered. +
- +
-Let's suppose that a measuring device is found Out-of-Tolerance. A measuring device that is found Out-of-Tolerance ≥200% over its stated accuracy is considered "//significantly//" Out-of-Tolerance (SOOT). Assume that a dimensional feature with a tolerance of ±0.001" was measured using an instrument accurate to ±0.0001". If this measuring instrument was found to be 200% Out-of-Tolerance (a SOOT condition), multiply the instrument accuracy (0.0001") by 2. Then determine your new accuracy ratio using the calculation of 0.001 ÷ 0.0002, which results in a new accuracy ratio of 5:1. Even with the measuring device "significantly" Out-of-Tolerance, the accuracy ratio (in this instance) is still above 4:1. So this would be justification for identifying the nonconformity as a minor. +
- +
-However, if the dimensional feature had a tolerance of ±0.001", and was measured using an instrument accurate to ±0.00015". Multiply that instrument accuracy (0.00015") by 2. Then determine your new accuracy ratio using the calculation of 0.001 ÷ 0.0003, which results in a new accuracy ratio of 3.3:1. Since this accuracy ratio is below 4:1, then this could be justification for a major nonconformity.+
  
 === Calibration during the audit === === Calibration during the audit ===
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 A major nonconformity is clearly justified. A major nonconformity is clearly justified.
  
-===== 7 - Fitness for Purpose #1 =====+===== 7 - Relocted Weighing Scale ===== 
 + 
 +__Situation__ A weighing scale was calibrated at a different location and then shipped to its current location. And there is no evidence that the calibration was repeated to verify that the weighing scale remained in-tolerance following the move.  
 + 
 +(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity? 
 + 
 +__Answer:__ The proper follow-up question is whether there is any documentation or record indicating that this specific model of weighing scale is immune from possible effects of \\  
 +  - the difference in local gravity acceleration, \\  
 +  - variation in environmental conditions, and/or \\  
 +  - mechanical and thermal conditions during transportation that likely altered the performance of the instrument? \\  
 + 
 +If the answer is no, and there is no other evidence to the contrary, this should be a Major nonconformance because we must assume that there is a high degree of probability that product quality (or quantity) has been affected. However, if the auditee has appropriate test weights (mass) providing an acceptable calibration accuracy ratio, and can verify that the weighing scale is in-tolerance during the audit, then this can be graded as a Minor Nonconformity (for not having a record of calibration AFTER the weighing scale was re-located). 
 + 
 +The basis for this nonconformity is found in [[https://www.euramet.org/Media/docs/Publications/calguides/I-CAL-GUI-018_Calibration_Guide_No._18_web.pdf|EURAMET Calibration Guide No. 18 (Version 4.0 (11/2015))]], page 5, which states:  
 +<blockquote>**4.1.2 Place of calibration** \\  
 +Calibration is normally performed in the location where the instrument is being used. \\  
 + \\  
 +If an instrument is moved to another location after the calibration, possible effects from \\  
 +  - difference in local gravity acceleration, \\  
 +  - variation in environmental conditions, \\  
 +  - mechanical and thermal conditions during transportation are likely to alter the performance of the instrument and may invalidate the calibration. \\  
 +Moving the instrument after calibration should therefore be avoided, unless immunity to these effects of a particular instrument, or type of instrument has been clearly demonstrated. Where this has not been demonstrated, the calibration certificate should 
 +not be accepted as evidence of traceability.</blockquote>  
 +===== 8 - Fitness for Purpose #1 =====
  
 [[ https://www.qclabels.com/Quality-Control-Labels/Limited-Calibration-Control-Stickers.aspx|{{  :articles:lpc440.jpeg?200}}]] [[ https://www.qclabels.com/Quality-Control-Labels/Limited-Calibration-Control-Stickers.aspx|{{  :articles:lpc440.jpeg?200}}]]
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-===== 8 - Fitness for Purpose #2 (AS9100 ONLY) =====+===== 9 - Fitness for Purpose #2 (AS9100 ONLY) =====
  
 __Situation:__ You observed micrometers being used throughout the production process; and you were told that the micrometers are calibrated "in-house". Upon reviewing the company's "//register of the monitoring and measuring equipment//" you discovered that they identify a calibration/verification method. Upon reviewing that calibration/verification method, you noticed that neither the “flatness" nor “parallelism” of the anvil with the spindle had been calibrated. You confirm this by examining calibration records for a sampling of the micrometers you observed in use. None of these records indicate that the “flatness" or “parallelism” of the anvil with the spindle had been calibrated. __Situation:__ You observed micrometers being used throughout the production process; and you were told that the micrometers are calibrated "in-house". Upon reviewing the company's "//register of the monitoring and measuring equipment//" you discovered that they identify a calibration/verification method. Upon reviewing that calibration/verification method, you noticed that neither the “flatness" nor “parallelism” of the anvil with the spindle had been calibrated. You confirm this by examining calibration records for a sampling of the micrometers you observed in use. None of these records indicate that the “flatness" or “parallelism” of the anvil with the spindle had been calibrated.
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  {{ youtube>NrLLmwi7-vE?large&rel=0 }}  {{ youtube>NrLLmwi7-vE?large&rel=0 }}
  
-===== 9 - The Incomplete "Register" (AS9100 ONLY) =====+===== 10 - The Incomplete "Register" (AS9100 ONLY) =====
  
 __Situation:__ Upon reviewing the company's "//register of the monitoring and measuring equipment//", which was maintained in an Excel spreadsheet, you discovered it did not include the: __Situation:__ Upon reviewing the company's "//register of the monitoring and measuring equipment//", which was maintained in an Excel spreadsheet, you discovered it did not include the: