ASME B89.7.3.3 pdf download.GUIDELINES FOR ASSESSING THE RELIABILITYOF DIMENSIONAL MEASUREMENT UNCERTAINTY STATEMENTS.
The primary purpose of this technical report is to provide guidelines for assessing the reliability of measurement uncertainty statements. Applying these guidelines can assist businesses in avoiding disagreements about measurement uncertainty statements and in resolving such disagreements should they occur. Disagreements nver uncertainty statements involving hoth single measurement systcms and multiple measurement systems (each having their own uncertainty statement) are considered. Guidance is provided for examining uncertainty budgets as the primary method of assessing their reliability. Additionally, resolution by direcl measurement of the measurand is also discussed.
1 SCOPE
1.1 Objective
This icchnical report provides guidance in asscssing the recliability of a statcment of mcasurement uncertainty in qucstion, that is, in judging whether that stated unccrtainty can be trusted to include the values that could reasonably be attributed to the measured quantity
(measurand) with which that stated uncertainty is associated.
1.2 Aplicability
This report is most applicablc to statements of unceruainty in the resuits of dimensional measurements based upon the ISO Guide 10 Expression of Uncertainty ir Measuremenl (GUM). (Also called ANSI/NCSL Z540-2.)
1.3 Purpose
This technical report helps parties to avoid potential, or resolve actual, disagreements over the magnitude of a stated measurement uncertainty, particularly when that uncertainty is part of a determination of conformity of a manufachured product to a dimensional specification.
The important point is that all infuence quantites of uhe measurement are accounled
for in some inpu quantity. In cerain cases. e.g. unceruainty evaluated by computer simulation, input quanditics are represented as paramelers that are allowed
00 vary betwcen simulation cycles.
5.3.2 Magnitudes of ncertainty Components (Standard Uncertainties of Input Quantities). After asceraining that each significant influence quantity is present in the uncertainty budgct
in some input quantity, the input quantities must be evaluated. The nagnitudes of uncerainty components are quantificd by standurd deviaions, known as standard uncrainties (GUM 4.1). Each input quanity has an associated standard uncerlainty. The value of the standard uncertainty must accounl for the range of values that could reasonably be atributed to the inpur quantity
over the time period that the measuremens ne peformed. Some ucerainty budgets pertain 10 a single measurcment that occurs in a short period of timc. Other uncertainty budgets might pertain to many subsoquent measurements, (as is ypical of production werkpiees), where the meas urement conditions, while being bounded, change from measurement to measurement.
The sime scale over which the measurements are performet must he comsidered. Am uncertainty hudget designet for a large numher nf mcasurements, e g。productiom workpiecs that are continuously protfuced and inspected over a long time scale (days. weeks. months. or years), will have greater variation in the input quanities than measurcments performed in a short time period. Consequendly. when delermining the standard uncertainties of the input quantities it is essensial 10 consider the full range of possible variations that may occur during the measurements. in addition, for uncerainty budgets that will apply to many subscquem measuremenis. the bounds on the permissible vaniation of the inpul quaniies under which the uneerainly budget is valid shwuld be cearly sulel.
Typc A slandard unceruainties are evaluated using stalisical means that are generally well dchined; however, it is erucial that the data (ully represent the input quantity to be quantifiod. For crample, if the uneetainty source associated with measurement reproducibility de
pends upon the opcerator, then scveral operators (not just one) must be included in the reprodueibility (Type A) datn. Differences in Type A standaurd uncertaintices usually result from failing to allow the input quantity to vary over the entire range of valucs permited in
the ueertainty budget.
ASME B89.7.3.3 pdf download
