STEP is an established ISO standard for the exchange of product data between different CAx and PDM/PLM systems. To promote the use of the standard, AFNeT, PDES, Inc. and prostep ivip have founded the MBx-IF as an umbrella organization for the established CAx-IF, PDM-IF and EWIS-IF projects. The aim of the joint project is to speed up the development of STEP interfaces and ensure that user requirements are met.
The MBx-IF addresses several STEP AP242 topics, namely Computer Aided Design (CAD), Product Data Management (PDM) and Electrical Wiring Interconnection Systems (EWIS). It provides a trusted environment for user companies and software vendors to openly discuss requirements and technical challenges, develop a common understanding of the issues, and derive robust approaches for implementation. The umbrella organization is intended to intensify the further development of the STEP standard through cross-cutting integration.
Implementation activities require a stable standard on which they can build. For this reason, the development of the ISO STEP standard is intensively pursued by providing bug fixes for problems encountered during testing and new features requested by the user community.
The new MBx-IF homepage has been set up at www.mbx-if.org . It contains all the information about the project, the topics and the different teams on a single website. Public documents such as Recommended Practices and Test Suites are available for download.
An important aspect of the applicability of a standard is the ability to easily visualize the data stored in that format. In 2024, all groups within the MBx-IF collected requirements for STEP viewer applications, which were summarized in a survey and distributed to an extensive list of STEP developers for self-assessment feedback. The results will be published in 2025.
The Recommended Practices represent a central added value of the MBx-IF for user companies and software manufacturers. Last year, these implementation guidelines were updated for a variety of topics, including product structure, kinematics and Product & Manufacturing Information (PMI).
In the field of CAx, a new series of test models with PMI was provided by the Japanese industry (JAMA/JAPIA) and tested for the first time. These complex production-level models present new challenges that help to improve the scope and robustness of STEP interfaces. For kinematics, the successful collaboration with JT-IF was continued. Work on persistent IDs, which are used to track information along the process chain, has been intensified.
The CAx-IF User Group gained new members, including Bosch and Schaeffler, thus increasing the diversity of requirements for CAD systems. The team prioritized the documented capabilities and functions and updated the requirements backlog for sheet metal bending parts.
The PDM user group worked on common PDM use cases as well as common topics within MBx-IF, including work orders for design changes and fasteners.
The PDM Implementor Group continued its work on the Recommended Practices for Domain Model XML, with many improvements reflecting the concepts of the upcoming Edition 4 of AP242. These are accompanied by Schematron rules that enable automated consistency checks beyond pure XML syntax validation. Testing of flexible parts and property groups has been completed, and testing of version branch effectivities, delta exchange, data compression and LOTAR product structure validation properties has been initiated.
The technical work on AP242 Edition 4 was completed in 2024. Important extensions from prostep ivip's point of view are the domain model extensions for assembly PMI, kinematics and visual issue management.
Following a yearlong break, the 3DMDM project group, which was previously divided into a Workflow Forum and Implementor Forum, has resumed its work with new focus as a joint group of user companies and vendors. The two are now working together with the aim of making it possible to exchange measurement data as an automated cloud service. One of the challenges faced was holding all the members of the project group together during the pandemic. The project group held a two-hour online workshop every month and used Miro whiteboards to document the results of the meetings in a way that was transparent for everyone involved.
As companies in many sectors are currently implementing strict cost-cutting measures, the financial environment remains difficult. Flexibility in organizing meetings to take account of travel restrictions and dividing the work between project groups with similar requirements helps to mitigate the impact of member turnover. Examples include the joint workshop on External Element References (EER) in Darmstadt in March, which brought together the STEP and JT working groups to work on common issues, and the joint meeting with manufacturing experts on Persistent ID in Phoenix in September.
On the technical side, a milestone was reached with the new joint MBx-IF website in spring 2024. It runs on a single, state-of-the-art server and a proven content management system and is much easier to maintain and use than the previous websites. The latest addition is the "Implementation Coverage" overview for CAx and PDM, which shows the supported STEP capabilities of the participating vendors and was also presented at the STEP AP242 Day in Hamburg.
The effective interaction between the standardization teams at ISO and the MBx-IF contributes significantly to achieving an early review of the AP242 model extensions. However, it is a challenge to carry out the standardization work in parallel with the development of the new agile processes at ISO (Jira, GIT).
EER, a mechanism that allows information to be linked to a specific element defined in another file, such as a specific surface or curve, will be a key issue in 2025. For PMI, this enables the definition of PMI at assembly level in AP242 XML with a part geometry defined in classic STEP Part 21 files. The same applies to the so-called kinematic pairs of higher order, e.g. a point that slides along a curve. These issues will be addressed in collaboration with the JT-IF, as the approach in AP242 XML is independent of the geometry format used.
Within the MBx-IF, the range of common topics between the domains will be expanded to include material properties and information on joining techniques such as fasteners and welding. Both the relevant metadata and the 3D representations are taken into account. The results of the STEP Viewer survey will also be compiled and published.
The PDM teams will drive forward the testing of current use cases and define new ones, such as material properties. The 4th edition of AP242 requires an update of the Recommended Practices as well as the STEP interfaces for use cases such as handling references in nested files, incremental exchange and delta exchange. Material properties are handled at the MBx-IF level, as are fasteners.
Other use cases such as export licenses and classification for export control will be continued. Testing of use cases such as design change work orders, version branch effects and LOTAR product structure validation features will continue.
ISO TC 184/SC 4 began planning a roadmap for the future of STEP. A Preliminary Work Item (PWI) was started for AP242 Edition 5. The focus in 2025 will be on defining the scope of application and developing an initial working draft. Prostep ivip members have expressed interest in the areas of PMI extensions, connectivity (interoperability with χMCF, CAx-IF and PDM-IF requirements), kinematics extensions, materials (revision of the STEP information model, harmonization with related VDA activities) and cooperative use of standards using ontologies.
"Collaboration between the project groups, particularly between CAx-IF and JT-IF, has become a key driver of success. The combination and harmonization of requirements from different user groups provide a broader basis for implementations. The ability to share test data between implementation groups increases both the number of vendors involved in a given functionality and the number of test iterations per year. It's a real win-win for everyone”.
Jochen Boy, PROSTEP
“The CAx-IF User Group has gained several new members this year. The fact that it is now a truly cross-industry forum representing users of different CAD systems significantly increases its importance. For their own members, who now have a more diverse audience to discuss their approaches and processes, and for the implementers, who now receive requirements that are the result of a greater consensus. We hope to continue this trend in all areas of MBx and attract even more members through the achievements of the teams.”
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