ASTM_F_1503_-_02_2012.pdf

Designation:F150302(Reapproved 2012)Standard Practice forMachine/Process Capability Study Procedure1This standard is issued under the fixed designation F1503;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.Scope*1.1 This practice covers provision of a proper method fordetermining process capability for new or existing machineprocesses.It is recommended that available statistical softwarebe used for the calculation of the descriptive statistics requiredfor decision making when using this practice.Where softwareis not available,Section 8 and Tables 1 and 2 are provided formanual calculations.2.Referenced Documents2.1 ASTM Standards:2F1469 Guide for Conducting a Repeatability and Reproduc-ibility Study on Test Equipment for Nondestructive Test-ing3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 bilateral specificationsspecifications that have bothupper and lower values.3.1.2 Cpan index that indicates the variability of theprocess with respect to tolerance.3.1.3 Cpkan index of process variability and centering.This is a widely-used index which considers the process mean,range,and its relation to the specification nominal.3.1.4 inspection plana set of instructions defining productcharacteristics,specifications,frequency of inspection,accep-tance criteria,and methods of inspection for product at aspecified operation.3.1.5 processparameterscombinationofpeople,equipment,materials,methods,and environment that produceoutput.3.1.6unilateral specificationsspecifications that haveonly upper or lower values.3.1.7 an estimate of the standard deviation of a processcharacteristic.4.Summary of Practice4.1 Amachine/process capability(MPC)study is conductedto provide a level of confidence in the ability of a machine/process to meet engineering specification requirements.This isaccomplished through statistical process control techniques asdefined in this practice.4.2 For new equipment purchases,the purchasers manufac-turing engineering department,or equivalent discipline,shallhave primary responsibility for ensuring that the requirementsof this practice are met.The purchasers quality assurancedepartment shall be available to assist on an as-requested basis.4.3 New machines/processes will not be accepted for use inproduction with Cpvalues less than 1.67.If a manufacturingprocessmustbeconditionallyaccepted,aprocessimprovement/product control plan shall be developed.4.3.1 The machine/process control plan shall identify spe-cific process improvement activities,which will be imple-mented to make the process more capable as well as an interiminspection plan to ensure that nonconforming product is notshipped to a customer.4.4 Product Specifications:4.4.1 Prior to any MPC study,the product specifications(nominal dimension and tolerances)must be identified,and anappropriate method of variables type inspection selected.4.4.2 This practice is limited to bilateral specificationswhose distributions can be expected to approximate a normalcurve.This practice should not be applied to unilateral speci-fications(flatness,concentricity,minimum tensile,maximumhardness,etc.).4.5 Gage Capability Analysis:4.5.1 All gaging systems used to evaluate product involvedin the study must have documentation for a gage repeatabilityand reproducibility study in accordance with Guide F1469before the machine/capability study is conducted.4.5.1.1 Gaging systems which consume 10%of the appli-cable product tolerance are considered acceptable.4.5.1.2 Gaging systems which consume over 10 to 30%ofthe applicable product tolerance are generally considered to beunacceptable.However,users of this guide may authorize their1This practice is under the jurisdiction of ASTM Committee F16 on Fastenersand is the direct responsibility of Subcommittee F16.93 on Quality AssuranceProvisions for Fasteners.Current edition approved Oct.1,2012.Published November 2012.Originallyapproved in 1994.Last previous edition approved in 2007 as F1503 02(2007).DOI:10.1520/F1503-02R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 use depending on factors such as the criticality of the specifi-cation in question,the cost of alternative gaging systems,andso forth.4.5.1.3 Gaging systems which consume more than 30%ofthe product tolerance are unacceptable and must not be used.4.5.2 All gaging systems must be certified as accurate usingstandards traceable to NIST,other recognized standa