ASME B1.25 pdf free download

ASME B1.25-2019 pdf free download.Measurement Uncertainty Factors in the Calibration of Screw Thread Gages.
(a) This Standard notes technical factors that can explain measurement differences between two parties calibrating the same gage. It is directed to the metrology involved, not acceptance rules or other quality considerations.
(b) While measurement uncertainty applies to the calibration of gages to any standard, this Standard focuses on gages made to ASME standards only. The calibration of gages necessitates a thorough understanding of the standards they were made to because the standards often include required conditions for and corrections to the calibration.
(c) Users of this Standard should be aware that while a number of elements for each gage type are listed. independent calibration laboratories may not include them all In their reports. Agreement should be reached with outside calibration providers as to what elements are induded in their various levels of calibration.
3 DEFINITIONS
3.1 GeneraL Definitions
,neasurernnt uncertainty: the amount that a measurement of size may differ from the true value of that feature. Every measurement contains an element ofuncertainty expressed as plus or minus from the reading of a size obtained, Uncertainty values determined by this Standard indicate the true measurement Is Included within the uncertarnty band with 95% confidence. With an expansion of the uncertainty value, the confidence of the true measurement being included could be raised to 99%.
It Is important to understand that there is no generic uncertainty fur a given process. Two laboratories having identical principal equipment will have different uncertainties due to variations In the factors noted In section 5.
Often several laboratories report the same or similar values for uncertainty due to rounding of the actual values to the nearest convenient value. For example, 12 pin. may be rounded to 15 pin, in a conservative budget.
uncertainty budget: a listing of all of the factors affecting a particular measurement and the mathematical method used to process each one to arrive at a total expanded uncertainty. Each factor is processed to show its common dimensional effect even though it may not be of dimensional origins, such as temperature or measurement force. Also called uncertainty statement.
3.2 DimensionaL CaLibration Definitions
The following terminology is commonly used in dimensional calibration: however, some terms may refer to thread gages and related devices only:
accuracy: an indication of the performance of an instrument, the dimensional state of a master, or the outcome of a process when compared to specified values. Per JCGM 2OO:2O12,accuracy Is not a quantity and is not given a numerical quantity value.
comparison: a dimensional measurement process in which the unknown size of a gage is compared to the known size of a master, such as a gage-block build-up. Some instruments, usually referred to as comparators, are designed for this type of short. range measurement only. Other devices with a long measurement range may be set up in a similar manner for improved precision. The performance of all devices used in this manner is limited by the uncertainty in the calibration of the dimensional master(s) used.ASME B1.25 pdf download.