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The new ISO 21920: What lies ahead for users

Marketing Team |

The new ISO 21920 series of standards combines and at the same time updates the previous ISO standards on surface finish profile. Heinz-Joachim Kedziora, Head of Surface Metrology Development, is the international project manager responsible for the third part of the new standard. We spoke with him about the current status, the contents and what Mahr customers will be facing in the future.

Mr. Kedziora, what is the current status of the new profile standard?
In April, the working group of ISO/TC 213 "Dimensional and geometrical product specifications and verificaton" concluded discussions on the "Final Draft Industry Standard" (FDIS). This means that the project managers must now incorporate the last agreed changes into the documents. As of now, technical changes are no longer possible. All ISO standards must comply with a guideline of more than 100 pages, in which the principles and rules for structuring as well as all specifications for layout are defined. Final drafts must be available at ISO headquarters in Geneva no later than August 15, 2021.

Did the pandemic delay the publication?
Yes, already in spring 2020 the so-called "Draft Industry Standard" had been completed and published for the first international vote, but some time passed until the working groups had met virtually. Therefore, we were granted an extension, which is not normally provided for in the standardization process.

What does the new ISO 21920 look like in concrete terms?
It consists of three individual parts. Part 1 covers the topic of "Drawing Entries," which defines the rules for specifying profiled surface finishes. Part 2 focuses on "Characteristics" and develops the terminology as well as the terms and parameters for the determination of the surface condition according to the stylus method. Part 3 deals in detail with "Measurement Conditions" by establishing a complete specification operator for surface finish by profiling methods.

Heinz-Joachim Kedziora, Leiter der Entwicklung Oberflächenmesstechnik

"Where the old standard provides reasonable results, the same is true for the new standard. Where the old standard was fuzzy, the new standard is clearer and more unambiguous."

Heinz-Joachim Kedziora
Head of Surface Metrology Development

Why was the new profile standard necessary?
The ISO 21920 series of standards replaces standards such as ISO 3274, 4287, 4288, 13565 and 1302. Some of the previous standards no longer corresponded to the current state of the art. Therefore, from today's point of view, a complete description of the surface finish on the manufactured component was not always clearly possible. Example: New production processes such as additive manufacturing pose different measurement challenges than the usual ablative manufacturing processes.

What exactly is changing in practice now?
Overall, great importance was attached to continuity in the standard and not everything was thrown overboard. Weak points of the old standard, unclean definitions or impracticable parameters have been removed. In principle, where the old standard provides reasonable results, this also applies to the new standard. Where the old standard was fuzzy, the new standard is clearer and more unambiguous. As an example: The filter settings were previously dependent on the workpiece, preliminary measurements were necessary, but almost no one carried them out. Therefore, it is no longer the workpiece that determines the filter setting, but the associated drawing.

So nothing changes for the bulk of our customers. Existing drawings naturally retain their validity. In addition, the new profile standards offer extended possibilities for functionally relevant product specification.

When will the standard be published and when will it apply?
A new review will take place in Geneva from August, so we expect publication in the fourth quarter, or at the latest in the first quarter of 2022.

Mr. Kedziora, thank you for talking with us!

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