Monthly Roundup: Mechanical Systems and Components Standards from October 2025

Looking back at October 2025, the Mechanical Systems and Components for General Use sector—encompassing everything from bearings and fasteners to springs—witnessed a notably active month in international standardization. Five new and updated standards were released, delivering vital updates to design calculation guidance, component characterization, handling practices, and testing parameters. For technical leaders, compliance managers, and R&D professionals, this monthly roundup is designed to distill not just what was published, but why it matters, how it fits into broader industry trends, and what steps organizations should be prioritizing now.

Monthly Overview: October 2025

The October 2025 publications in the Mechanical Systems and Components for General Use category highlighted both evolutionary and transformative changes in core component standards. Significantly, the month brought:

• A strong emphasis on plain bearing reliability and practice, with new guidance on both hydrodynamic journal bearing calculations and everyday handling procedures
• Updated harmonized specifications for grooved pins and fasteners, including the coordinated publication of ISO and EN ISO versions to support global and European industry alignment
• New standardized measurement and verification procedures for compression springs, advancing quality assurance and process repeatability

This robust activity marks an uptick from typical monthly releases, suggesting growing industry demand for harmonization, performance assurance, and streamlined compliance in the face of increasingly intricate mechanical assemblies. The month's mix of updates—ranging from detailed tribiological calculations to component handling and dimensional testing—signals a holistic approach to quality and reliability across the mechanical supply chain.

Standards Published This Month

ISO 31657-4:2025 - Permissible Operational Parameters for Multi-Lobed and Tilting Pad Journal Bearings

Plain bearings - Hydrodynamic plain journal bearings under steady-state conditions - Part 4: Permissible operational parameters for calculation of multi-lobed and tilting pad journal bearings

ISO 31657-4:2025 establishes the critical operational parameter guide values needed for reliably calculating and safeguarding the performance of multi-lobed and tilting-pad journal bearings operating in steady-state conditions. Targeting engineers involved in the design, selection, and maintenance of hydrodynamic plain bearings, the standard sets forth empirical—and modifiable—limits for start-up, run-down, and ongoing operation, as well as measures to avoid thermal and mechanical overloading.

Organizations dealing with rotating machinery, heavy industrial equipment, or power generation infrastructure rely on these recommendations to optimize bearing selection, achieve longer bearing life, and prevent costly unplanned downtime through proper calculation and risk mitigation. As the updated successor to ISO/TS 31657-4:2020, this edition is now a full International Standard and benefits from error corrections and closer coordination with ISO 31657-1 for terminology, symbols, and reference calculation methods.

Key highlights:

• Provides operational limits for critical characteristics (hmin, Tlim, plim) during start-up/run-down
• Focuses on avoiding overloading based on geometric and technological properties in tribological systems
• References broader calculation methods from ISO 31657-1 and empowers tailored application for special operating contexts

Access the full standard:View ISO 31657-4:2025 on iTeh Standards

EN ISO 8739:2025 - Parallel Grooved Pins, with Pilot Point — Full-Length Diamond Grooves (European Adoption)

Fasteners - Parallel grooved pins, with pilot point - Full-length diamond grooves (ISO 8739:2025)

EN ISO 8739:2025 is the European adoption of ISO 8739:2025, harmonizing fastener specifications across CEN member countries. This standard defines the characteristics of parallel grooved pins with a pilot point and full-length diamond grooves, in both steel and stainless steel, covering nominal diameters from 1 mm to 25 mm. These distinctive pins offer superior pull-out resistance by virtue of their diamond-grooved and elastic fit—and the pilot point ensures easy, reliable installation for assembly operations involving locking two or more components.

Manufacturers, assemblers, and procurement teams across the mechanical, automotive, and general machinery sectors will find uniform terminology, dimensional requirements, materials (now including additional steel and stainless grades), and clear references to ISO 13669 for general requirements and assembly methods. The EN ISO adoption strengthens consistency and market access across Europe by setting a single, unified reference that replaces previous national variants.

Key highlights:

• Defines dimensions, tolerances, material grades, and finishes for grooved pins with full-length diamond grooves
• Enables standardized assembly, procurement, and quality control across global and European supply chains
• Mandates labelling and traceability provisions for packaging to support robust supply chain management

Access the full standard:View EN ISO 8739:2025 on iTeh Standards

ISO 8739:2025 - Parallel Grooved Pins, with Pilot Point — Full-Length Diamond Grooves

Fasteners - Parallel grooved pins, with pilot point - Full-length diamond grooves

ISO 8739:2025 provides the global specification framework for parallel grooved pins used for robust, high-retention mechanical connections. Addressing both steel and stainless steel pins (now expanded to more grades and additional diameters), this third edition supersedes the 1997 version by introducing new terms and definitions, updated principles of assembly, improved mechanical property fidelity (including shear resistance and hardness), and enhanced provisions for product inspection/traceability.

At its core, the standard supports applications—from industrial machinery and automation to automotive subassemblies—where ease of assembly, repeatable fit, and resistance to axial loads are paramount. The updated references to general requirements and test protocols (such as ISO 13669) help ensure manufacturing conformity and predictable in-service performance.

Key highlights:

• Updates product scope to include additional diameters and stainless steel grades
• Clarifies key assembly, fit, and inspection parameters for high-reliability connections
• Reinforces international harmonization with corresponding EN ISO adoption

Access the full standard:View ISO 8739:2025 on iTeh Standards

ISO 21433:2025 - Handling of Plain Bearings

Plain bearings - Handling of plain bearings

ISO 21433:2025 presents crucial requirements and guidance covering the full lifecycle of plain bearings—including storage, transportation, handling, installation, operational supervision, and replacement. The revision reflects evolving best practice and unifies terminology to promote global consistency.

This standard’s audience spans production planners, maintenance engineers, logistics professionals, and service managers supporting industries where plain bearings are core to performance (e.g., power generation, transportation systems, food processing, and industrial automation). The specification addresses protection against physical damage, contamination, and corrosion—covering details from choice of packing and labeling to the control of temperature and humidity in storage.

Operational procedures include not only installation methods (press fit, screw-fixing, keyed, shrink fitting) but also best practices for running-in, lubrication system cleaning, and scheduled inspection. Lifecycle management is enhanced through its prescriptive approach to documentation, record keeping, and bearing replacement protocols.

Key highlights:

• Comprehensive rules for plain bearing storage, packing, and environmental control
• Clear installation, monitoring, and replacement guidelines for maximum bearing service life
• Supports reliability-centered maintenance and root cause mitigation strategies

Access the full standard:View ISO 21433:2025 on iTeh Standards

EN ISO 22705-1:2025 - Measurement and Test Parameters: Cold Formed Cylindrical Helical Compression Springs

Springs - Measurement and test parameters - Part 1: Cold formed cylindrical helical compression springs (ISO 22705-1:2021)

EN ISO 22705-1:2025 standardizes the measurement and verification procedures for the key characteristics of cold formed cylindrical helical compression springs made from round wire (excluding dynamic testing). This standard is integral for quality control, procurement specification, and product validation in industries relying on precision spring performance—such as automotive, electronics, and mechanical assembly.

Specifying a suite of dimensional and mechanical test parameters—including free length, outside and inside diameter, coil count, solid length, spring load, pitch, ground surface, and perpendicularity—the standard instructs on test equipment, methods, locations, and environmental conditions to ensure repeatable and reliable results.

The EN ISO 22705-1:2025 adoption brings European alignment with ISO protocols, encouraging supply chain transparency and cross-border part interchangeability.

Key highlights:

• Covers all major dimensional and physical properties for compression springs
• Introduces harmonized measurement/test procedures and definitions
• Lays the foundation for process capability studies and fair product procurement

Access the full standard:View EN ISO 22705-1:2025 on iTeh Standards

Common Themes and Industry Trends

The cluster of October 2025 publications reflects several clear industry trends:

• Lifecycle Reliability and Practicality: Updated standards for plain bearings (both for calculation and handling) emphasize durability, predictive maintenance, and operational safety. These updates track with broader moves toward reliability-centered maintenance (RCM) and digital twins in asset management.
• Harmonization and Global Consistency: The dual publication of ISO and EN ISO fastener standards, as well as spring measurement standards, demonstrates a push for universal specifications supporting open markets and direct comparability of products across borders.
• Quality Assurance and Verification: Test and measurement standards for springs, and updated inspection and traceability rules for fasteners, highlight a rising expectation for verifiable, reproducible quality at every stage—from raw materials to assembly.
• Inclusion of New Materials and Dimensional Ranges: Extensions to stainless steel grades and diameter options in fastener standards mean more flexibility for designers and procurement, addressing niche applications and non-standard environments.

As manufacturing complexity and supply chain internationalization increase, the sector’s standards are clearly steering toward holistic quality and risk management, data-driven validation, and cross-functional process integration.

Compliance and Implementation Considerations

For organizations affected by these October 2025 standards, effective implementation requires a systematic approach:

Immediate Priorities:

1. Gap Analysis: Evaluate current design, procurement, and maintenance practices against the new standards’ requirements—especially for bearings, fasteners, and springs.
2. Supply Chain Alignment: Engage with suppliers to ensure they are producing and certifying to the most recent specifications, especially for harmonized EN ISO products.
3. Staff Training: Update procedures and train operational, quality, and maintenance personnel on revised practices (e.g., bearing handling, spring testing).

Timeline Considerations:

• Consider the time required for engineering change notices, supplier requalification, and process documentation updates.
• Note that withdrawal or replacement of conflicting national standards (particularly for EN ISO adoptions) typically occurs within 6-12 months post-publication.

Resources

• Full standards documentation and guidance can be accessed via iTeh Standards, which also supports notification tracking and integration into compliance management systems.
• ISO and CEN technical committees often release guidance notes, interpretation bulletins, or training materials to assist with implementation.

Conclusion: Key Takeaways from October 2025

The October 2025 standards releases mark a significant step forward for professionals dedicated to best-in-class mechanical system performance. Whether in design engineering, preventive maintenance, procurement, or quality assurance, there are clear imperatives to:

• Review and adopt updated parameters for hydrodynamic bearing calculation and handling
• Standardize fastener procurement and usage to reflect new dimensional and performance specifications, fostering cross-border compatibility
• Advance spring evaluation procedures to guarantee predictable and validated mechanical properties

Ultimately, keeping current with these standards not only ensures compliance but supports continuous improvement, operational excellence, and market competitiveness. For those who may have missed these key publications, now is the time to review, realign, and raise the bar on mechanical systems reliability.

For further information and access to the authoritative texts, explore the standards directly via iTeh Standards.