ISO 4288:1996 pdf free download.Geometrical Product Specifications (GPS) Surface texture: Profile method Rules and procedures for the assessment of surface texture.
1 Scope
ISO 4288 specifies the rules for comparison of the measured values with the tolerance limits for surface texture parameters defined in ISO 4287, Iso 12085. ISO 13565-2 and ISO 13565-3.
It also specifies the default rules for selection of cutoff wavelength. k, for measuring roughness profile parameters according to ISO 4287 by using stylus instruments according to ISO 3274.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of ISO 4288. At the time of publication, the editions indicated were valid. All standards are subiect to revision, and parties to agreements based on ISO 4288 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 1302:1992, Technical drawings — Method of mdicating surface texture.
ISO3274:1996, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Nominal characteristics of contact (stylus) instruments.
Iso 4287:1996. Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions and parameters of surface texture.
ISO 12085:1996, Geometncal Product Specifications (GPS) — Surface texture: Profile method — Motif parameters.
ISO 13565-1:1996. Geometrical Product Specifications (GPS) — Surface texture: Profile method; surfaces having stratified functional properties — Parr 1 Filtering and general measurement conditions.
ISO 13565-2:1996, Geometrical Product Specif ications (GPS) — Surface texture: Profile method; surfaces having stratified functional properties — Parr 2:
Height characterization using the linear material ratio curve.
ISO 13565-3:— 1), Geometrical Product Specifications (GPS) — Surface texture: Profile method; surfaces having stratified functional properties — Part 3: Height characterization using the material probability curve.
ISO 14253-1: — U. Geometrical Product Specifications (GPS) — Inspection by measurement of workpièces and measuring instruments — Part 1: Decision rules for proving conformance or non-conformance with specifications.
3 Definitions
For the purposes of this International Standard, the definitions given in ISO 3274, Iso 4287, ISO 12085, ISO 13565-2 and ISO 13565-3 apply.
4 Parameter estimation
4.1 Parameters defined over the sampling length
4.1.1 Parameter estimate
An estimate of the parameters value is calculated using the measured data from only one sampling length.
4.1.2. Average parameter estimate
An average parameter estimate is calculated by taking the arithmetic mean of the parameter estimates from all the individual sampling lengths.
When the standard number of five sampling lengths is used for roughness profile parameters, no suffix needs to be added to the symbol. For a parameter evaluated over a number of sampling lengths other than five, that number shall be added as a suffix to the parameter symbol (eg. Rzl, Rz3).
4.2 Parameters defined over the evaluation length
For parameters defined over the evaluation length (Pt. Ri and Wi). an estimate of a parameters value is calculated by using measurement data from an evaluation length equal to the standardized number of sampling lengths.
4.3 Curves and related parameters
For curves and related parameters, an estimate of a parameter’s value is calculated by using measurement data from one curve, which has been computed based on the evaluation length.
4.4 Default evaluation lengths
If not otherwise indicated on the drawing or in the technical product documentation, the evaluation length is as follows:
— R-parameters: the evaluation length is defined in clause 7;
— P-parameters: the evaluation length is equal to the length of the feature being measured;
— motif-parameters: the evaluation length is defined in clause 5 of ISO 12085:1996;
— parameters defined in ISO 13565-2 and ISO 13565-3: the evaluation length is defined in clause 7 of ISO 13565-1:1996.4 Parameter estimation
4.1 Parameters defined over the sampling length
4.1.1 Parameter estimate
An estimate of the parameters value is calculated using the measured data from only one sampling length.
4.1.2. Average parameter estimate
An average parameter estimate is calculated by taking the arithmetic mean of the parameter estimates from all the individual sampling lengths.
When the standard number of five sampling lengths is used for roughness profile parameters, no suffix needs to be added to the symbol. For a parameter evaluated over a number of sampling lengths other than five, that number shall be added as a suffix to the parameter symbol (eg. Rzl, Rz3).
4.2 Parameters defined over the evaluation length
For parameters defined over the evaluation length (Pt. Ri and Wi). an estimate of a parameters value is calculated by using measurement data from an evaluation length equal to the standardized number of sampling lengths.
4.3 Curves and related parameters
For curves and related parameters, an estimate of a parameter’s value is calculated by using measurement data from one curve, which has been computed based on the evaluation length.
4.4 Default evaluation lengths
If not otherwise indicated on the drawing or in the technical product documentation, the evaluation length is as follows:
— R-parameters: the evaluation length is defined in clause 7;
— P-parameters: the evaluation length is equal to the length of the feature being measured;
— motif-parameters: the evaluation length is defined in clause 5 of ISO 12085:1996;
— parameters defined in ISO 13565-2 and ISO 13565-3: the evaluation length is defined in clause 7 of ISO 13565-1:1996.
5 Rules for comparison of the measured
values with the tolerance limits
5.1 Areas on the feature to be inspected
The surface texture of the workpiece under inspection can appear homogeneous or be quite different over various areas. This can be seen by visual examination of the surface. In cases where the surface texture appears homogeneous, parameter values determined over the entire surface shall be used for comparison with the requirements specified on the drawings or in the technical product documentation.
If there are separate areas with obviously different surface texture, the parameter values which are determined on each area shall be used separately for comparison with the requirements specified on the drawings or in the technical product documentation.
For requirements specified by the upper limit of the parameter, those separate areas of the surface shall be used which appear to have the maximum parameter value.
5.2 The 16 %-rulo
For requirements specified by the upper limit (see ISO 1302:1992, 6.2.3) of a parameter, the surface is considered acceptable if not more than 16 % of all the measured values (see notes 1 and 2) of the selected parameter, based upon an evaluation length, exceed the value specified on the drawings or in the technical product documentation.
For requirements specified by the lower limit of the surface parameter, the surface is considered acceptable if not more than 16 % of all the measured values (see notes 1 and 2) of the selected parameter, based upon an evaluation length, are less than the value specified on the drawings or in the technical product documentation.
To designate the upper and the lower limits of the parameter. the symbol of the parameter shall be used without the “max.’ index,
NOTES
1 Annex A provides simplified practical guidance for comparing measured values with upper and lower limits.
2 In cases where the values of the roughness profile parameter of the surface being inspected follow a normal distribution, the determination of the upper limit as a limit which may be exceeded by 18 % of the measured values of the roughness profile parameter conforms with the limit determined by the value p + where p is the arithmetic mean value of the roughness profile parameter and a is the standard deviation of the values. The greater the value of a, the further from the specified limit (the upper value) the mean value of the roughness profile parameter needs to be. (See figure 1.)
7.2.1 Procedure for non-periodic roughness profile
For surfaces with a non-periodic roughness profile, the following procedure shall be followed.
a) Estimate the unknown roughness profile parameter Ra, Rz, RzI max. or RSm by any means preferred, for example visual inspection, roughness comparison specimens, graphical analysis of a total profile trace. etc.
b) Estimate the sampling length from table 1. 2 or 3, using the Ra, liz, Rzl max. or RSm estimated in step a).
c) With a measuring instrument, obtain a representative measurement of Ra, Rz, Rzl max. or RSm, using the sampling length estimated in step b).
d) Compare the measured value of Ra, liz. R1 max. or RSm, with the range of values of Ra. Rz, Rzl max. or RSm in table 1, 2 or 3 corresponding to the estimated sampling length. If the measured value is outside the range of values for the estimated sampling length, then adjust the instrument to the respective higher or lower sampling length setting indicated by the measured value, Then measure a representative value using this adjusted sampling length and compare again with the values in table 1. 2 or 3. At this point the combination suggested by table 1, 2 or 3 of the measured value and the sampling length should have been reached.
e) Obtain a representative value of Ra, Rz. R1 max. or RSni, for one sampling length setting shorter if this shorter sampling length setting has not previously been evaluated in step d). Check to see if the resufting combination of Ra, liz. RzImax. or RSne and sampling length is also that specified by table 1. 2 or 3.
f) If only the final setting of step d) corresponds to table 1. 2 or 3, then both the sampling length setting and the Ra, liz. Rzl max. or RSm value are correct. If step e) also produces a combination specilied by table 1. 2 or 3, then this shorter sampling length setting and corresponding Ra. Rz, Rzlmax. or RSm value are correct.
g) Obtain a representative measurement of the desired parameter(s) using the cut-off wavelength value (sampling length) estimated in the preceding steps.
7.2.2 Procedure for periodic roughness profile
For surfaces with a periodic roughness profile, the following procedure shall be used.
a) Estimate graphically the parameter RSm of the surface of unknown roughness.