ISO 6626-2:2024

Overview

ISO 6626-2:2024 specifies the essential dimensional features of coil-spring-loaded oil control rings of narrow width, made of cast iron, for internal combustion engines. This part of the ISO 6626 series covers seven types of oil control rings (DSF-C, SSF, GSF, DSF, SSF-L, DSF-NG, DSF-CNP) and applies to sizes ranging from 60 mm up to 160 mm nominal diameter. The standard is relevant for reciprocating internal combustion engines, particularly those used in road vehicles but also suitable for other applications.

By defining dimensional features and designations, ISO 6626-2 enables the global interchange, selection, and specification of piston rings in engine design and manufacturing. Adherence to this standard supports consistent performance, compatibility, and quality assurance for engine components.

Key Topics

• Piston Ring Types and Designation:
  The standard details the dimensional features for various cast iron coil-spring-loaded oil control ring types:

  • DSF-C: Bevelled edge, chromium plated, profile ground
  • DSF-CNP: Bevelled edge, chromium plated, not profile ground
  • SSF: Slotted, rectangular groove
  • GSF: Double bevelled
  • DSF: Bevelled edge
  • DSF-NG: Similar to DSF-C/DSF-CNP, bevelled edge
  • SSF-L: Slotted, rectangular groove with additional V-shaped groove

• Essential Dimensions:
  Covers groove widths, slot arrangements, spring groove configurations, and tolerances for widths, land width, and wall thickness across the supported diameter range.

• Coil-Spring Specifications:
  Addresses spring types (constant/variable pitch), materials (as per ISO 6621-3), excursion, and gap positions, ensuring proper load and performance characteristics for oil control.

• Tangential Force and Nominal Contact Pressure:
  Provides formulas for calculating tangential force and nominal contact pressure, both of which are vital for oil control and friction management in the piston assembly.

• Surface Treatments and Plating:
  Specifies chromium plating thickness for certain ring types and defines relevant tolerances, ensuring durability and wear resistance.

Applications

ISO 6626-2:2024 is pivotal for designers, manufacturers, and quality assurance teams in the automotive and engine-building industries. Practical uses include:

• Engine Design and Manufacturing:

  • Selecting and specifying suitable oil control piston rings during engine development.
  • Ensuring the interchangeability and compatibility of engine parts globally.

• Quality Assurance:

  • Conformance assessment and inspection of piston rings to ensure that dimensional and material requirements are consistently met.

• Aftermarket and Maintenance:

  • Providing reliable references for replacement piston rings to meet OEM specifications and maintain engine integrity.
  • Facilitating global sourcing of compliant piston rings for repair and rebuilds.

• Other Applications:

  • Applicable beyond road vehicles, supporting other reciprocating engines in industrial, marine, and power generation sectors.

Related Standards

For comprehensive piston ring specification and compatibility, ISO 6626-2:2024 should be used alongside other key standards:

• ISO 6621-3: Internal combustion engines - Piston rings - Part 3: Material specifications
  (Defines material classes for cast iron and springs.)

• ISO 6621-4: Internal combustion engines - Piston rings - Part 4: General specifications
  (Covers general requirements such as marking, surface finish, and tolerances.)

• ISO 6621-5: Internal combustion engines - Piston rings - Part 5: Quality requirements
  (Outlines quality control and testing protocols.)

• ISO 6626-1: Internal combustion engines - Piston rings - Part 1: Tabulated dimensions
  (Provides reference dimensions and additional contact pressure classes.)

• Other Related ISO Standards:
  ISO 6622, ISO 6623, ISO 6624, ISO 6625, and ISO 6627 offer further guidance for various types and applications of piston rings.

Summary

Implementing ISO 6626-2:2024 ensures efficiency, performance, and durability in internal combustion engine design through standardized dimensions and specifications for coil-spring-loaded oil control rings. By referencing this standard throughout engine development, manufacturing, and maintenance, organizations benefit from improved product reliability, global compatibility, and streamlined quality processes.