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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. But current discussions may lead to new documents. In August 2016, the project was officially registered under the reference: ISO 21920.Īt 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. 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. 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. Then came RMS or Rq, Rz and Rmax, and later many more parameters so many in fact that Pr Whitehouse eventually wrote his famous paper about parameter rash. For a long time, only one parameter was known and used, under the name Ra (Roughness average) or CLA (Center Line Average) or even AA (Arithmetic Average). The measured profile was drawn on a carbon paper and a value of roughness was given on a galvanometer.
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The first roughness testers recorded surface heights using a stylus tip in contact with the surface and a traverse unit. Profile Parameters Surface texture of mechanical components has been checked over 80 years in order to improve performances of manufactured products.
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