The markings on the piston pin corresponding to piston pin standard ISO 18669 are shown in Figure 1.
The piston pin standard DIN 73216 has been internationally revised and published as ISO 18669-1 and 18669-2. Part 1, "General Specifications," lists the markings, piston pin types, dimensions and tolerances, materials, heat treatment, and quality characteristics. Part 2 deals with measurement and test methods.
Most of piston pin manufactures from North America whose piston pins are designed, manufactured, and applied on the basis of the ISO 18669 standard.
The important design criteria listed in the standard-core hardness, hardness penetration depth, surface hardness, volume stability, and surface roughness-are provided in below tables.
Table 1. Core hardness (core strength)
|
Wall thickness a [mm] |
Core hardness HV 30 (core strength Rm [MPa]) |
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|
Class L |
Class M |
Class N |
|
|
1.5–2 |
310–515 (1,000–1,650) |
310–470 (1,000–1,500) |
310–470 (1,000–1,500) |
|
>2–5 |
280–485 (900–1,575) |
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|
>5–10 |
270–470 (850–1,500) |
280–470 (900–1,500) |
|
|
>10–15 |
250–470 (800–1,500) |
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|
>15–25 |
235–470 (750–1,500) |
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|
>25 |
250–435 (800–1,400) |
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The core strength values (Rm) are provided for reference only and are calculated from the core hardness HV with a factor of 3.2.
Table 2. Hardness penetration depths, dimension in mm
|
Wall thickness a [mm] |
Case depth |
Nitride depth |
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|
Outside |
Inside min. |
Outside and inside together |
Outside min. |
Inside min. |
|||
|
Min. |
Code X |
Max. |
Code X |
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|
1.5– < 2 |
– |
0.4 |
0.1 |
0.65 · a |
0.80 · a |
0.3 |
0.2 |
|
2–3 |
0.3 |
0.5 |
0.1 |
0.65 · a |
0.80 · |
||
|
> 3–5 |
0.4 |
0.6 |
0.2 |
0.50 · a |
0.65 · a |
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|
> 5–15 |
0.6 |
– |
0.4 |
0.35 · a |
– |
||
|
> 15 |
0.8 |
– |
0.6 |
0.35 · a |
– |
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Comment 1: the limit hardness used in determining the case depth is Hs 550 HV.
Comment 2: for piston pins with limited change in volume, identification mark V, the limit hardness is Hs 500 HV.
Comment 3: code X: applies to piston pins used with needle bearing in the conrod bore.
