ISO 12179:2000 pdf download
ISO 12179:2000 pdf download.Geometrical Product Specifications (GPs)-Surface texture:Profile method -Calibration of contact (stylus) instruments.
If the basic equipment is used with several drive units and probes, each of these instrumental combinations (configurations) shall be calibrated separately.
4.2 Calibration of a configuration
The contact (stylus) instrument shaU be calibrated when a change is made to the basic elements of the system which intentionally or unintentionally modifies the measured profile/measuring result. Each configuration of the contact (stylus) instrument shall be calibrated separately.
EXAMPLE Wth a change of probe the contact (stylus) instrument shall be calibrated.
4.3 Place of calibration
The contact (stylus) instrument should be calibrated at the place of use with environmental conditions similar to those present when in use for measurement to take into account external influence factors.
EXAMPLE Noise, temperature, vibration, air movement, etc.
5 Measurement standards
The following measuring standards are applicable to the calibrations given in clause 6:
— optical flat;
— depth measurement standard (Figure 1): type A according to Iso 5436-1;
— spacing measurement standard (Figure 2): type C according to ISO 5436-1;
— inclined optical flat (Figure 3);
profile co-ordinate measurement standard (consisting of a sphere or prism): type E according to ISO 5436-1;
– – roughness measurement standard (Figure 4): type D according to ISO 5436-1.
NOTE it is recommended that a profile co-ordinate measurement standard be used on contact (stylus) instruments where the stylus rotates plus and minus one half of a degree when moving through its full range.
6 Contact (stylu8) instrument metrological characteristics
Only those task-related contact (stylus) instrument metrological characteristics which are relevant for the intended measurements should be selected for calibration. For example, for the measurement of spacing parameters, the vertical profile component need not be calibrated.
6.1 Residual profile calibration
The scratch-free optical flat reproduces the residual profile. For task-related calibrations use the appropriate profile and parameters (for example: the roughness profile with Ra, Rq or Ri; the waviness profile with Wq or Wi).
NOTE By using this approach the effects of external guide straightness, environmental conditions and instrument noise can be established.
6.3 Horizontal profile component calibration
The spacing measurement standard reproduces the mean width of profile element, PSm, in order to measure the error of indication of the horizontal profile component.
6.4 Profile co-ordinate system calibration
The inclined optical flat reproduces:
— the least squares best fit angle in degrees;
— the total height of the primary profile, Pr, after removal of the least squares best fit straight line;
thus establishing the error of the linked horizontal and vertical co-ordinates (i.e. variation in traverse speed, nonlinearities in scales, etc.).
The profile co-ordinate measurement standard reproduces the total height of the primary profile, Pt, after removal of the least squares best fit nominal form, thus establishing the co-ordinate system.
6.5 Calibration of the total contact (stylus) instrument
The roughness measurement standards reproduce the:
arithmetical mean deviation, Ra;
— maximum height of profile Rz;
thus establishing an overall check of the total contact (stylus) instrument.
7 Calibration
7.1 Preparation for calibration
Before calibration, the contact (stylus) instrument shall be checked to determine if it operates correctly as described in the manufacturers operating instructions. The condition of the stylus tip shall also be checked according to the manufacturer’s instructions.
For contact (stylus) instruments the following shall be complied with.
— The residual profile is to be evaluated.
— The plane of the depth measurement standard shall be aligned to the reference surface in the best possible way. All measurement standards shall be aligned properly, for example the plane of the roughness measurement standard shall be aligned to within 10% of the measuring gauge range but not more than 10 lim over the evaluation length.
— In task related calibrations, roughness measurement standards shall be used with the appropriate roughness comparable to the roughness of the surface to be measured.
— Measurements shall be taken in the middle of the vertical measuring range of the probe each time.
— A sufficient number of measurements shall be taken on each measurement standard for the required measurement uncertainty, (see clause 8). Repeated measurements are usually necessary due to the inhomogeneity of the measurement standard, the variability of the measurement procedure, and the repeatability of the contact (stylus) instrument.
