ISO 6624-1:2017

Overview

ISO 6624-1:2017 - "Internal combustion engines - Piston rings - Part 1: Keystone rings made of cast iron" specifies the essential dimensional features and designation rules for keystone piston rings made of cast iron. It covers ring types T, TB, TBA, TM, K, KB, KBA and KM, intended for reciprocating internal-combustion piston engines with nominal diameters from 70 mm up to and including 200 mm. The 2017 (3rd) edition updates coating/PVD thickness guidance and reflects technological improvements.

Key topics and technical requirements

• Ring types and geometries
  • Type T / K - straight-faced keystone rings (T = 6°, K = 15°)
  • Type TB / KB - symmetrical barrel faced
  • Type TBA / KBA - asymmetrical barrel faced
  • Type TM / KM - taper faced (multiple taper codes)
• Dimensional features
  • Essential dimensional tables, figures and designation examples for nominal diameters and widths
  • Separate tables for 6° and 15° keystone variants, plus common feature tables
• Materials and subclasses
  • Cast-iron ring material options and subclass examples (e.g., MC12, MC22, MC32, MC53) are used for designation
• Surface treatments and coatings
  • Uncoated, chromium plated, PVD coated, spray coated, phosphate or ferroxide coatings - configurations and minimum thickness classes are referenced
  • PVD coating thickness included in this edition
• Force factors and mechanical data
  • Tables of force factors and ring forces to guide design and selection
• Manufacturing features
  • Options for machined or lapped peripheral surfaces, internal bevels/chamfers and twist features
• Designation format
  • Standardized example format: Piston ring ISO 6624-1 T-90 × 2,5-MC12/CR2

Applications - who uses this standard

• Engine designers and powertrain engineers - to select ring geometry and material compatible with piston/cylinder designs
• Piston ring manufacturers and foundries - to produce keystone rings to standardized dimensions, tolerances and coating classes
• OEMs and suppliers - for procurement specifications and part designation consistency
• Quality, testing and inspection labs - to verify dimensional conformity, surface treatment and force characteristics
• Aftermarket and service - to match replacement rings to engine requirements

Related standards

• Normative reference: ISO 6621-4 (Piston rings - General specifications)
• ISO piston-ring series: ISO 6621, ISO 6622, ISO 6623, ISO 6625, ISO 6626, ISO 6627 - consult these for complementary requirements and full ring-system specifications

Keywords: ISO 6624-1, piston rings, keystone rings, cast iron, internal combustion engines, ring dimensions, ring coatings, ring designation, engine design.