ISO 21940-11:2016/Amd 1:2022

Overview

ISO 21940-11:2016/Amd 1:2022 is an important amendment to the international standard focusing on mechanical vibration and rotor balancing. Specifically, it addresses the procedures and tolerances for rotors exhibiting rigid behavior. Developed by ISO Technical Committee ISO/TC 108, this amendment enhances the guidelines and practices essential for achieving precise rotor balancing, which is critical in various industrial applications involving rotating machinery.

The amendment includes updated normative references and introduces a new clause emphasizing the importance of notifying necessary balancing information during the design stage. It also adds Annex E, which provides practical guidance on documenting unbalance tolerances on technical drawings-key to ensuring consistent and effective rotor balancing processes.

Key Topics

• Procedures for Rotor Balancing
  Defines updated operational procedures and methods to effectively balance rotors with rigid behavior, improving machine reliability and vibration control.

• Unbalance Tolerances
  Specifies recommended unbalance tolerances and criteria critical to rotor safety, operational efficiency, and longevity.

• Design Stage Notification
  New clause recommends communicating rotor-specific parameters such as balance quality grade, maximum operational speed, rotor mass, bearing planes, and unbalance tolerances at the design phase to facilitate comprehensible and accurate balancing.

• Technical Drawing Guidance (Annex E)
  Provides a clear checklist of necessary balancing details to be included on technical drawings or supplementary documents, such as:

  • Balance quality grade (G)
  • Maximum operational speed (rpm)
  • Rotor mass
  • Bearing and correction planes
  • Tolerance planes linked to permissible residual unbalances
  • Position of the rotor’s center of mass
  • Instructions for unbalance correction methods

• Collaboration and Standardization
  Reflects ISO’s collaboration with related electrotechnical committees and global standards bodies to maintain harmonized and universally applicable balancing practices.

Applications

This amended standard is essential for engineers, designers, and maintenance professionals involved in:

• Rotating Machinery Design
  Providing designers with guidelines to specify unbalance tolerances early in development, ensuring balanced rotors and reduced vibration-related issues.

• Manufacturing and Quality Control
  Enabling precise quality checks during production to meet balance quality grades, enhancing product reliability.

• Maintenance and Repair
  Offering practical procedures and correction guidelines for balancing rotors during servicing or refurbishment.

• Vibration Analysis and Condition Monitoring
  Supporting technicians in assessing rotor behavior consistent with rigid balancing requirements, enabling predictive maintenance and avoiding unexpected machine failures.

ISO 21940-11:2016/Amd 1:2022 thus plays a critical role in industries such as aerospace, automotive, power generation, and mechanical engineering, where rotor dynamics directly impact performance and safety.

Related Standards

To fully leverage ISO 21940-11 amendments, users should also consider:

• ISO 21940-1: Mechanical vibration - Rotor Balancing - Part 1: Introduction
  Provides fundamental concepts and the basis for understanding rotor balancing principles referenced in the amendment.

• ISO 21940-2: Mechanical vibration - Rotor Balancing - Part 2: Vocabulary
  Standardizes terminology essential for clear communication in rotor balancing procedures.

• ISO 21940-14: Mechanical vibration - Rotor balancing - Part 14: Assessment of balancing errors
  Complements Part 11 by focusing on detailed evaluation and quantification of balancing inaccuracies.

These interconnected standards support comprehensive expertise in rotor balancing, ensuring adherence to internationally accepted practices and enhancing machine reliability worldwide.

Keywords: ISO 21940-11 amendment, rotor balancing procedures, rigid rotors, mechanical vibration standards, unbalance tolerances, rotor design guidelines, technical drawing unbalance, rotor balancing information, international rotor balancing standard, ISO mechanical vibration