Today, profile parameters and areal parameters are defined in a handful of international standards that sometimes have local variations due to national or sectorial standards. Profile parameters are separated into three groups depending on the type of profile from which they are calculated: P parameters are calculated on the Primary Profile; R parameters are calculated on the roughness profile; and W parameters are calculated on the waviness profile.
In order to overcome problems arising in the early profilometers, such as noise or repeatability, some parameters are meant to be calculated on profile segments (sampling lengths) and then averaged. The sampling length is usually defined as the cut-off length (λc) of the filter used to separate roughness and waviness. For example, using a cut-off length of 0.8 mm and 5 sampling lengths, parameters will be estimated on each segments (Ra1, Ra2, ., Ra5) and the parameter value will be given as the mean of these estimated values. Other parameters are defined and calculated on the evaluation length which usually is the profile length after filtering. Details are given in [ISO 4288].
Note that the same parameters calculated according to ASME B46.1 are not averaged and are calculated on the evaluation length. Their value slightly differ from the parameters calculated according ISO.
Sampling length = 2,5 mm
This standard describes the most common profile parameters, such as Ra, Rz or RSm.
La méthode R&W de l'ISO 12085 permet de caractériser les structures périodiques sur un profil. Cette méthode née dans les années 1980 est maintenant étendue grâce à une segmentation plus robuste issue de l'analyse surfacique.
Célèbres paramètres fonctionnels, utilisés dans l'automobile, les Rk, caractérisant différentes parties de la courbe d'Abbott.
In fall 2012, the WG16 group of ISO TC 213 decided to start revising profile standards in order to align them with the ISO 25178 structure and concepts. Basically, the new structure will consist of at least three parts:
In August 2016, the project was officially registered under the reference: ISO 21920.
At this stage, there is no plan to describe instruments characteristics or calibration as this was included in ISO 25178 parts 60x and 70x, as well as parts 7x for material measures and softgauges. But current discussions may lead to new documents.
Principles have been discussed in 2013 at the Helsinki meeting and a first draft of Part 2 was established by a task force within the group. The first official New Work Item Proposal was issued to Geneva Central Secretariat in Fall 2016. The current drafts have reached DIS stage in Spring 2020. Voting comments will be discussed in September and the FDIS stage could be launch by the end of the year, with an official publication mid-2021. After the publication of this 3-parts standard, the old profile standards will probably be canceled (ISO 1302, 4287, 4288, 12085, 13565-2, 13565-3)
This standard today is more in line with ISO standards than the previous versions, except for some differences. The main difference is about sampling length and averaged parameters. In ASME, all profile parameters are defined and calculated on the evaluation length.
This standard from the German automotive industry collects parameters defined in ISO 4287 and ISO 13565 and introduces several rules that differ from ISO. The main difference concerns the use of microroughness filter λs that is prohibited here. It also reintroduces the parameter Rmax that was once part of ISO 4287 and is a good complement to Rz.
This standard defines special parameters for the evaluation of periodic surfaces, especially in the field of mating surfaces. It is usually referred to as Dominant waviness. It defines three parameters calculated after a special zero bandpass filter:
WDSm, horizontal waviness
WDc, mean height of waviness profile elements
WDt, total waviness profile height
These parameters are part of the Automotive module.
This internal standard provides methods and parameters to analyze lead-reduced dynamic sealing surfaces. It is referred to as Lead or Twist analysis. The following parameters are calculated:
DG, number of threads
Dt, lead depth
DP, period length
DF, theoretical supply cross section
DFu, DF per turn
DLu, contact length
Dγ, lead angle
DSγ, offset lead angle
This standard is available in the Lead Analysis (Twist) module.
This internal standard defines one parameter to caracterize the waviness profile:
Wst, maximum absolute height difference of the waviness profile
MountainsMap offers several options to comply to these standards. ISO parameters are all available in MountainsMap but sometimes as an option (such as the Automotive Module). ASME B46.1 is offered as a family in the Parameter study. VDA 2006 can be implemented by disabling the microroughness option in the Preferences. VDA2007 and MBN 31 007-12 are part of the Automotive Module. The Daimler Lead method is available as a separate Lead Analysis (Twist) Module.