In fact, according to the ISO 4287 standard, different Sampling Lengths apply to the Primary Profile, the Waviness Profile and the Roughness Profile. Put in other words, it is the distance required for being able to include enough small irregularities for a relevant evaluation while not including non-relevant long wavelength components. The Sampling Length is defined in the ISO 4287 standard as “the length in the X direction used for identifying the irregularities characterizing the profile under evaluation”. Sampling Length, Evaluation Length and Number of Cut-Offs Therefore this option has been omitted in SPIP™. λf filtering is, however, rarely used in practice and is also not well specified in the ISO standards. The Waviness Profile is simply the difference between the Primary Profile and the Roughness Profile, though according to the ISO 4287 standard the Waviness Profile is the Primary Profile filtered using a cut-off wavelength λf in order to suppress long wave components followed by suppressing short wave components using the λc cut-off wavelength. Nominal values for λs and λc given in the ISO 3274:1996 written standard. If it is necessary to deviate from the standards, this should always be properly specified. Guidelines to choice of evaluation length and λc cut-off (same as sampling length) is provided in the ISO 4288 standard. The inter relationship between the two cut-off values, the stylus (or tip) radius and the point spacing is also given in the ISO 3274 standard and is reproduced in the following table.
#Cut off wavelength series
(Note, that the end-effect correction applied when using the ISO 11562 filter in the Filter Dialog or from Quick Launch follows the “Border Mode” for the used filter setting, which differs from this method).Īccording to the ISO 3274:1996 written standard the nominal values for λs and λc should follow the series This means that in the majority of cases it is not necessary to exclude the end regions of the profile from the parameter calculations. In order to reduce distortions from the filtering process at the ends of the profile, end effect correction using the moment retainment criterion of 1st order as described in the ISO 16610-28:2008 standard is applied. Hence, the Roughness Profile contains the shorter roughness components of the profile. This filter suppresses long wave lengths using the λc cut-off wavelength specified in the user interface. The Roughness Profile is generated by applying a high pass Gaussian filter according to the ISO 11562:1996 standard, see Filters in Users Guide, and the new ISO 16610-21 standard. In order to comply with the ISO standard framework it is mandatory to subtract the nominal form of the raw profile and to suppress short wave lengths using a λs filter according to the nominal values given in the ISO 3274 standard, see table below. The Primary Profile is generated from the raw profile as described in the general section for profile roughness steps. The ISO 4287 Primary, Waviness and Roughness Profiles The standard has also been elaborated in various text books and is described on various web pages such as NPL-Softgauges. The ISO 4287 written standard is available (for purchase) from ISO (and from various national standardization bodies. However, it is strongly recommended to study the original written standards. SPIP™ helps the user to evaluate roughness of profiles according to this framework of standards, by providing relevant default choices for filter cut-offs and by providing warnings and information in the bottom of the Roughness Analysis pane. ISO 16610-21 Filtration – Linear profile filters: Gaussian filters / ISO 16610-28 Filtration - profile filters – End effects.ISO 11562 Surface texture: Profile method – Metrological characteristics of phase correct filters.ISO 4288 Surface texture: Profile method – Terms, definitions and surface texture parameters.ISO 4287 Surface texture: Rules and procedures for the assessment of surface texture.ISO 3274 Surface Texture: Profile method – Nominal characteristics of contact (stylus) instruments.The ISO 4287 written standard is part of a frame work of Geometrical Product Specifications (GPS) standards comprising: When using the ISO 4287 standard in a “nonstandard” way it is very important in any reporting to specify exactly how the analysis was set-up. The mathematics of course also works for profiles recorded by other tools and for shorter or longer profiles. The scope of this framework of ISO standards is to provide methods for general evaluation of surface texture using stylus profilometers which typically record profiles with lengths of several millimeters. You are here: Reference Guide > Roughness and Texture Parameters > The ISO 4287:1997 Standard The ISO 4287:1997 Written Standard