Internal combustion engines. Piston rings. Keystone rings made of cast iron
1Key Takeaways
This document specifies the basic dimensional characteristics of trapezoidal rings made of cast iron, types T, TB, TBA, TM, K, KB, KBA and KM, with diameters from 70 mm to 200 mm inclusive, for reciprocating internal combustion piston engines.
2Expert Interpretation
Professional analysis of ISO 6624-1:2017, the technical specification for cast iron trapezoidal piston rings, covering dimensional tolerances, mechanical properties, and coating requirements for 6° and 15° trapezoidal rings suitable for engines with a cylinder diameter of 70-200mm. Compare the differences between the old and new versions and provide selection and implementation recommendations.
Analysis of the core content of the standard
| Technical parameters | 6° trapezoidal ring | 15° trapezoidal ring |
|---|---|---|
| Radial wall thickness tolerance | ±0.024mm | ±0.029mm |
| Tangential force range | 9.9-65.8N | 11.2-63.4N |
| Typical coating thickness | Chrome plating 0.005-0.2mm | PVD coating 0.001-0.05mm | |
Key technology evolution
Compared with the 2001 version of the standard, the 2017 version has the following major updates:
- Added PVD coating thickness specification (Table 8)
- Optimized the mechanical properties of heat-treated ductile iron (MC53)
- Revised the dimensional tolerance band of asymmetric barrel rings (TBA/KBA)
Selection and implementation recommendations
Typical application scenarios
High-speed diesel engines recommend the use of KB type 15° symmetrical barrel rings:
- Barrel surface curvature radius h26 = 0.45-0.65mm (Table 1)
- Tangential force correction factor 0.88-0.96 (Table 10)
- Combined with SC4F spray coating, wear resistance can be improved by 40%
Test points
According to ISO 6621-2 requirements:
- The trapezoidal width h3 must be measured with a special taper gauge
- The coating thickness must be measured using a magnetic induction thickness gauge
- Tangential force test tolerance: ±30% when Ft < 10N, ±20% when ≥ 10N