ISO 3611:2010 pdf free download – Geometrical product specifications (GPS)一Dimensional measuring equipment: Micrometers for external measurements一Design and metrological characteristics.
5 Metrological characteristics
5.1 General
The metrological characteristics specified in this International Standard apply when the zero or reference point is set at any position within the measuring range, i.e. in floating zero mode. Unless otherwise specified by the manufacturer, micrometers for external measurements shall comply with the maximum permissible error (MPE) and permissible limit (MPL) values at any orientation of the micrometer. For test methods to evaluate the performance of the micrometer, refer to Annexes C and D.
5.2 Effect of spindle clamp
If the spindle is clamped (in cases where the frame is equipped with a clamping device), the dimension which
is set shall not change and the indication should not change by more than 2 pm.
5.3 Maximum permissible error of indication (limited by MPE)
5.3.1 General
The requirements on the error of indication apply to any indication based on the zero or reference point setting
stated in 5.1. For an example of a diagram of error of indication, see Annex A.
5.3.2 Full surface contact error, J (limited by MPEJ)
Error of indication when full measuring face contact (3.2.1) is employed at any position of the measuring range. If the micrometer has a rotating measuring spindle, the measurements should be carried out in fractions of
one revolution.
5.3.3 Repeatability, R (limited by MPER)
Error of indication when full measuring face contact (3.2.1) is employed on successive measurements of the same measurand, carried out under the same conditions of measurement.
5.3.4 Partial surface contact error, E (limited by MPEE)
The error of indication MPEE applies when partial measuring face contact (3.2.2) is employed on successive measurements of the same measurand, carried out at any position of the measuring faces, under the same conditions of measurement.
If the micrometer has a rotating measuring spindle, the measurements should be carried out in fractions of one revolution.
NOTE The partial surface contact error includes the flatness of the measuring faces, the parallel deviation of the measuring faces and the perpendicularity deviation of each measuring face to, respectively, anvil’s and spindle’s axis.
5.4 Measuring forces (limited by MPL)
The measuring force shall be given as a maximum and minimum measuring force.
5.5 Instrument specification sheet
The methods should permit evaluation of the performance of the instrument within its measuring range. The global calibration of each scale point or each digital step over the measuring range will necessitate a large number of readings to be taken. When it is considered that the intended use of the instrument does not warrant global calibration, partial calibration or task-related calibration should be taken into consideration. When determining the errors of indication, it is necessary to choose a suitable number of intervals, dependent on the scale interval or digital step, the measuring range and the used measuring range. The values of maximum permissible errors can be calculated according to ISO 14978. With these values, calibration curves with a floating zero can be recorded (see ISO 14978:2006, Figure 7).
It is possible to perform a calibration by using a suitable sampling technique, but this will result in an increase in the uncertainty of measurement.