ASME B1.25:2019 pdf free download

ASME B1.25:2019 pdf free download.Measurement Uncertainty Factors in the Calibration of Screw Thread Gages.
indicate the true measurement is included within the uncertainty 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 for 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 bud,qe: 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 200:2012, “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 or the dimensional master(s) used.
cosine error: an error that results when the feature being measured, such as a diameter, is not normal (square) to the axis of measurement. This error may be encountered when plug gages rest on a worktable that cannot be adjusted to offset it. It may also appear in the direct measurement of solid thread ring gages. In both cases, it occurs because either the face or table the gage is resting on is not square to the axis. It can also be found indevices that mount the gage on centers that are not alignedproperly.
functional size: a size, such as a diameter, that contains allelements it is comprised of such that it could be larger onan external thread or smaller on an internal thread thanindicated by discrete measurement for the dimension(e.g. diameter) alone (see ASME B1.7).