BS ISO 20852-2020 Textiles一Determination of the total heat transfer through textiles in simulated environments.
The single-stylus, multi-stylus, opposing-styli and scanning mode errors and their corresponding maximum permissible errors shall be expressed in micrometres.
For each test specified in Clause 6 the same data set shall be used to evaluate both size and form as requested. It is not permitted to take two data sets, one for size and one for form.
For articulating systems, data for at least one method of qualification, either inferred or empirical, is required.
NOTE 1 The single-stylus probing error also applies to CMMs used with fixed multiple probes, fixed multiple styli and articulating probing systems (see 6.3.1).
NOTE 2 Multi-stylus probing performance is broadly categorized into form-related (PForm.Sph.5×25:j;Tact), size-related (Psize.Spli.5×25:j:Tacj, and location-related (LDja.5×25:j:Tact and LDIa.proj.Sph.2×25:j:Tact) errors. Different combinations of these will be important for the uncertainty of the different measurement tasks. For example, the form and size results might contain information on the ability of the CMM system to use multiple stylus tip diameters in the measurement of a single geometrical feature wherej is replaced by MS, MP, Emp, or ml, as applicable. See also Annex C.
NOTE 3 An articulating probing system used at multiple angular positions, even when used with a single stylus, is deemed to be a multi-stylus probing system.
NOTE 4 The limits of the probing system configuration for the single-stylus, scanning mode test and the multi- stylus test are allowed to differ from each other.
6.2 Measuring equipment
6.2.1 Test sphere
For both single-stylus and multi-stylus tests in this document, the test sphere shall have a diameter not less than 10 mm and not greater than 51 mm.
For the scanning mode test, the test sphere shall have a diameter not less than 24,9 mm and not greater than 25,5 mm.
The test sphere shall be calibrated for size and form. For the tests in this document, the measurand for sphere size is the least-squares diameter and the measurand for sphere form is sphericity. Calibration organisations use different approaches for sphericity. Common approaches for sphericity are for example: a minimum of 3 orthogonal great circle traces; or using 25 or more points well distributed on the sphere. For size, common approaches are for example: measuring the distance between two diametrically opposite points and other approaches that fit to more than two measured points.
For MPE form specifications, this document includes the sphere form as a rated operating condition to be able to exclude the influence of the test sphere form (with its uncertainty) from the test value uncertainty. However, a manufacturer is still permitted to explicitly state that the imperfect form of the test sphere is not a rated operating condition, in which case the influence of the form of the test sphere (with its uncertainty) shall be included in the test value uncertainty (as in ISO/TS 17865).
Unless the manufacturer states that the imperfect form of the test sphere is not a rated operating condition, or different percentages (for the below conditions), or an absolute maximum value for the calibrated form (Fai) (i.e. a different rated operating condition), then the calibrated form (Faj) and calibration uncertainty (U(Fai)) of the test sphere shall meet all the following requirements for all of the associated MPEs shown below that will be tested using the test sphere:
— Fai shall not exceed 20 % of PForm.sph,1×25:ss:Tact,MPE or Prorrn.sph.5ic25:j:Tact,MPE or PForm.Sph.Scan:k:Tact,MPE where j is replaced with MS, MP, Emp or lnf as applicable and where k is replaced with PP or NPP as applicable;BS ISO 20852 pdf pdf download.