ASTM_F_1469_-_11.pdf

Designation:F146911Standard Guide forConducting a Repeatability and Reproducibility Study onTest Equipment for Nondestructive Testing1This standard is issued under the fixed designation F1469;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide describes the steps required to conduct acomplete repeatability and reproducibility(RR)study onnondestructive test equipment.This guide is a manual(use ofcalculator)method.Other methods may utilize the applicationof computer driven software.1.2 This guide can be used to evaluate all test equipmentthat provides variable measuring data.2.Terminology2.1 Definitions:2.1.1 repeatabilityvariation in the values of measurementsobtained when one operator uses the same gage for measuringidentical characteristics of the same parts.2.1.2 reproducibilityvariation in the average of measure-ments made by different operators using the same parts.3.Significance and Use3.1 This guide is recommended for the purpose of evaluat-ing test equipment that may be utilized in statistical processcontrol,testing laboratories,and for in-process control ofmanufacturing operations.3.2 Ask the question:What effect does the operator have onthe measurement process?If possible,the operators whonormally use the test equipment should be included in thestudy.If operator calibration of the equipment is likely to be asignificant cause of variation,then the operator should recali-brate the equipment prior to each group of readings.3.3 The test equipment should provide direct readings inwhich the smallest digit is no larger than one tenth of thetolerance of the characteristic being evaluated.3.4 It is recommended that a test equipment repeatabilityand reproducibility study be a mandatory part of all testequipment purchases and that acceptance criteria be 10%forcertification and statistical process control(SPC)use.4.Equipment Certification4.1 Test equipment shall be certified through use of certifiedstandards as accurate to the manufacturers/users calibrationsystems with certified standards before a repeatability andreproducibility study is performed.4.2 Certifications must be traceable to the National InstituteofStandardsand Technology(NIST),orrecognizedequivalent,and shall be current to the test equipments cali-bration schedule.5.Procedure5.1 Although the number of operators,trials,and parts maybe varied,the following guidelines represent the optimumconditions for conducting a study using the forms in Figs.1and 2.5.2 Select three operators and identify them as Operators A,B,and C.5.3 Calibrate the test equipment with a certified standard.5.4 Select ten parts for measurements and number themfrom 1 to 10,such that the numbers,if possible,are not visibleto the operator.Place a mark on each part to indicate theprecise position at which the part shall be measured.Thiseliminates the variation within the part from the study resultsso that only the gages performance and operator variationinfluences the study outcome.5.5 Allow Operator A to inspect all ten parts in a sequentialorder by measuring each part at the designated location.Enterthe results in the 1st trial column for Operator A of theRepeatability and Reproducibility Data Sheet(Fig.1).Partidentification and associated data entry shall be performed byan observer.5.6 Repeat 5.5 with Operators B and C and enter the resultsin the corresponding 1st trial column for each operator.5.7 Repeat 5.5 and 5.6 using a random selection of the tenparts.Enter data in the 2nd trial column for each operator.Ifthree trials are needed,repeat the cycle and enter data in thecorresponding 3rd trial column for each operator.1This guide is under the jurisdiction of ASTM Committee F16 on Fasteners andis the direct responsibility of Subcommittee F16.93 on QualityAssurance Provisionsfor Fasteners.Current edition approved May 1,2011.Published May 2011.Originallyapproved in 1993.Last previous edition approved in 2010 as F1469 99(2010).DOI:10.1520/F1469-11.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.8 Steps 5.5,5.6,and 5.7 may be changed to the followingwhen large part size or simultaneous availability of parts is notpossible:5.8.1 Allow Operators A,B,and C to measure the first partand record their readings in the corresponding 1st trial columnsfor each operator.5.8.2 Allow Operators A,B,and C to remeasure the first partand record their readings in the corresponding 2nd trialcolumns for each operator.If three trials are to be used,repeatthe cycle and enter the results in the corresponding 3rd trialcolumns for each operator.5.9 If the operators are not available at the same time,thefollowing method may be used.Allow Operator A to measureall ten parts at once and ente