ISO/DIS 18669-1

Internal combustion engines -- Piston pins

Moteurs à combustion interne -- Axes de pistons

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 18669-1
ISO/TC 22/SC 34 Secretariat: ANSI
Voting begins on: Voting terminates on:
2020-06-01 2020-08-24
Internal combustion engines — Piston pins —
Part 1:
General specifications
Moteurs à combustion interne — Axes de pistons —
Partie 1: Spécifications générales
ICS: 43.060.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
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STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 18669-1:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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ISO/DIS 18669-1:2020(E)
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© ISO 2020

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ii © ISO 2020 – All rights reserved
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ISO/DIS 18669-1:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Terms and definitions ..................................................................................................................................................................................... 1

2.1 General ........................................................................................................................................................................................................... 1

2.2 Geometrical and manufacturing features of piston pins .................................................................................... 1

2.2.1 Bore types .............................................................................................................................................................................. 1

2.2.2 Outside-edge configurations ................................................................................................................................. 2

2.2.3 Other features ..................................................................................................................................................................... 2

3 Symbols .......................................................................................................................................................................................................................... 2

4 Nomenclature .......................................................................................................................................................................................................... 3

4.1 Outside, inside and end features ............................................................................................................................................. 3

4.2 Outside edge and inside chamfer configurations ...................................................................................................... 6

4.2.1 Chamfered outside-edge configuration ........................................................................................................ 6

4.2.2 Double-chamfered outside-edge configuration .................................................................................... 6

4.2.3 Radiused outside-edge configuration ............................................................................................................ 7

4.2.4 Chamfer-locking outside-edge configuration ......................................................................................... 7

4.3 Outside-edge drop-off configuration ................................................................................................................................... 8

5 Codes ................................................................................................................................................................................................................................. 9

6 Designation of piston pins .......................................................................................................................................................................10

6.1 Designation elements and order ..........................................................................................................................................10

6.1.1 Mandatory elements ..................................................................................................................................................10

6.1.2 Additional elements ...................................................................................................................................................10

6.2 Designation examples ....................................................................................................................................................................10

7 Piston pin types, dimensions and tolerances ......................................................................................................................11

7.1 Manufacturing types .......................................................................................................................................................................11

7.2 Dimensions and tolerances .......................................................................................................................................................11

7.2.1 Outside diameter and form and location tolerances .....................................................................11

7.2.2 Inside diameter tolerance .....................................................................................................................................13

7.2.3 Length (l ) and gauge length (l ) tolerances ........................................................................................13

1 5

7.2.4 Outside-edge form .......................................................................................................................................................14

7.2.5 Inside-edge profile ......................................................................................................................................................15

7.2.6 Tapered bore dimensions ......................................................................................................................................16

7.2.7 Centre-web dimensions (see Figure 17) ..................................................................................................17

8 Material and heat treatment .................................................................................................................................................................17

8.1 Type of material ..................................................................................................................................................................................17

8.2 Core hardness l core strength .................................................................................................................................................18

8.3 Carburised and nitrided case depth ..................................................................................................................................19

8.4 Surface hardness ................................................................................................................................................................................19

8.5 Volume change .....................................................................................................................................................................................20

9 Common features ..............................................................................................................................................................................................20

9.1 Roughness of surfaces ...................................................................................................................................................................20

9.1.1 Roughness of machined surfaces ....................................................................................................................20

9.1.2 Roughness of coated surfaces ............................................................................................................................21

9.1.3 Roughness of extruded and seamless drawn bore surfaces ....................................................21

9.2 Marking of piston pins ...................................................................................................................................................................21

9.3 Miscellaneous ........................................................................................................................................................................................22

9.3.1 Cleanliness .........................................................................................................................................................................22

9.3.2 Corrosion protection .................................................................................................................................................22

9.3.3 Residual magnetism ...................................................................................................................................................22

9.3.4 Packaging.............................................................................................................................................................................22

10 Quality requirements ...................................................................................................................................................................................22

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ISO/DIS 18669-1:2020(E)

10.1 Material characteristics ................................................................................................................................................................22

10.1.1 Decarburisation .............................................................................................................................................................22

10.1.2 Cementite network .....................................................................................................................................................22

10.1.3 Nitride coating ................................................................................................................................................................22

10.1.4 Grinder burn .....................................................................................................................................................................22

10.2 Material defects ...................................................................................................................................................................................22

10.2.1 Cracks .....................................................................................................................................................................................23

10.2.2 Forming streaks .............................................................................................................................................................23

10.3 Visual defects .........................................................................................................................................................................................23

Bibliography .............................................................................................................................................................................................................................25

iv © ISO 2020 – All rights reserved
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ISO/DIS 18669-1:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2. www .iso .org/ directives

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received. www .iso .org/ patents

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.
The committee responsible for this document is ISO/TC 22, Road vehicles.

This second edition cancels and replaces the first edition (ISO 18669-1:2004), which has been

technically revised.

ISO 18669 consists of the following parts, under the general title Internal combustion engines —

Piston pins:
— Part 1: General specifications
— Part 2: Inspection measuring principles
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DRAFT INTERNATIONAL STANDARD ISO/DIS 18669-1:2020(E)
Internal combustion engines — Piston pins —
Part 1:
General specifications
1 Scope

This part of ISO 18669 specifies the essential dimensional characteristics of piston pins with a nominal

outer diameter from 8 mm up to and including 100 mm, for reciprocating internal combustion engines

for road vehicles and other applications. In certain applications, except road vehicles, and provided that

mutual agreement is made between the customer and the manufacturer, this part of ISO 18669 may be

used with suitable modifications.

In addition, it establishes a vocabulary, a pin-type classification, material description based on

mechanical properties, common features and quality requirements.

The use of this part of ISO 18669 may require a manufacturer and customer statistical process control

agreement.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1 General
2.1.1
piston pin

precision cylindrical component that connects the piston to the connecting rod and has a smooth hard

peripheral surface
2.2 Geometrical and manufacturing features of piston pins
2.2.1 Bore types
2.2.1.1
cylindrical
pin having a straight cylindrical bore
2.2.1.2
centre web

pin inside diameter formed symmetrically from each end leaving a web in the pin centre

Note 1 to entry: The web is subsequently removed leaving a step as shown in Figure 3.

2.2.1.3
tapered

pin with conical-shaped inside diameter near the ends that reduces the weight of the piston pin

2.2.1.4
machined
pin with inside diameter produced solely by machining
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ISO/DIS 18669-1:2020(E)
2.2.1.5
seamless drawn tube

hollow steel product which does not contain any line junctures resulting from the method of

manufacture
2.2.1.6
end web
pin inner diameter formed from one end leaving a web near the opposite end

Note 1 to entry: The web is punched out. The pin is then drawn over a mandrel and a forming line may result as

shown in Figure 4.
2.2.2 Outside-edge configurations
2.2.2.1
chamfer

outside-edge bevelled feature that is sometimes used to mate with a round retainer ring

Note 1 to entry: Referred to as “locking chamfer” when a round wire retainer ring is located on the chamfer angle

and used to secure the pin in the piston.
2.2.2.2
form angle δ

region of outside-edge form that provides a smooth transition to the peripheral surface to facilitate

ease of assembly
2.2.2.3
form angle γ
region of outside-edge form that provides a smooth transition to the end face
2.2.2.4
drop-off

non-functional machining feature that creates a transition between the outside edge and the

peripheral surface
Note 1 to entry: See Figure 12.
2.2.2.5
inside-edge chamfer
bevelled edge between the bore surface and the end faces of the piston pin
2.2.2.6
gauge point

locating point on the pin outside-edge chamfer from where the gauge diameter (d ) and gauge length

(l ) are measured
2.2.3 Other features
2.2.3.1
volume change

change detected as a permanent outside-diameter dimensional deviation at reference temperature

after being heated to a test temperature for a specified period of time
2.2.3.2
slag lines
linear flaws of non-metallic inclusions
3 Symbols
For the purposes of this part of ISO 18669, the symbols in Table 1 apply.
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ISO/DIS 18669-1:2020(E)
Table 1 — Symbols
Symbol
Description
abbreviation
a Wall thickness
b Outside-edge drop-off length
c Outside-edge drop-off height
d Outside diameter
d Inside diameter
d Tapered bore diameter
d Centre-web diameter
d Gauge diameter
d End face diameter
e Tapered bore runout
f Outside-edge length
g Outside-edge chamfer length
H Limit hardness
h End face concavity
h End face step
k Tapered bore relief
l Length
l Tapered bore length
l Centre-web length
l Gauge length
r Outside-edge radius
R Core strength
s End face runout
t Inside-edge chamfer length
t Outside-edge form length
α Tapered bore angle
β Outside-edge chamfer angle
γ Outside-edge form angle end face
δ Outside-edge form angle
4 Nomenclature
4.1 Outside, inside and end features

Terms commonly used to describe pins with a cylindrical bore are shown in Figure 1.

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ISO/DIS 18669-1:2020(E)
Key
1 end face
2 bore surface
3 peripheral surface
d outside diameter
d inside diameter
l Length
a wall thickness
See Figure 2.
Figure 1 — Pin with cylindrical bore
Terms commonly used to describe end face concavity are shown in Figure 2a).
Terms commonly used to describe end face step are shown in Figure 2b).
a) End face concavity b) End face step
Key
h end face concavity
h end face step
d end face diameter
NOTE End face concavity and end face step not recommended for end face locking.
Figure 2 — Detail W of Figure 1
Terms commonly used to describe pins with a centre web are shown in Figure 3.
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ISO/DIS 18669-1:2020(E)
Key
1 centre-web radius
l centre-web length
d centre-web diameter
Figure 3 — Pin with cold-formed centre web

Terms commonly used to describe pins with a cold-formed end-web are shown in Figure 4.

Key
1 end-web forming line
Figure 4 — Pin with cold-formed end web
Terms commonly used to describe pins with a tapered bore are shown in Figure 5.
Key
1 tapered bore surface
α tapered bore angle
d tapered bore diameter
l tapered bore length
Figure 5 — Pin with tapered bore
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ISO/DIS 18669-1:2020(E)
4.2 Outside edge and inside chamfer configurations

Terms commonly used to describe the outside edge and inside chamfer configurations are shown in

Figure 6.
Key
1 outside-edge chamfer or radius
2 inside-edge chamfer
t inside-edge chamfer length
See Figures 7 and 8.
See Figure 9.
NOTE This may be used with either a round or rectangular retainer ring.
Figure 6 — Outside-edge configuration (detail X: chamfered; detail Y: radiused)
4.2.1 Chamfered outside-edge configuration

Terms commonly used to describe the chamfered outside-edge configuration are shown in Figure 7.

Key
f outside-edge length
β outside-edge chamfer angle
Figure 7 — Chamfered configuration (detail X of Figure 6)
4.2.2 Double-chamfered outside-edge configuration

Terms commonly used to describe double-chamfered outside-edge configurations are shown in

Figure 8. The double chamfer is for assembly improvements of the piston pin.
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ISO/DIS 18669-1:2020(E)
Key
F outside-edge length
G outside-edge chamfer length
Δ outside-edge form angle
Β outside-edge chamfer angle
Figure 8 — Double-chamfered configuration (detail X of Figure 6)
4.2.3 Radiused outside-edge configuration

Terms commonly used to describe radiused outside-edge configurations are shown in Figure 9.

Key
R outside-edge radius
F outside-edge length
Δ outside-edge form angle
Figure 9 — Radiused configuration (detail Y of Figure 6)
4.2.4 Chamfer-locking outside-edge configuration

Terms commonly used to describe chamfer-locking outside-edge configurations are shown in

Figures 10 and 11.
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ISO/DIS 18669-1:2020(E)
Key
1 gauge points
l gauge length
d gauge diameter
Figure 10 — Chamfer-locking outside-edge for round retainer ring
Key
1 gauge point
g outside-edge chamfer length
f outside-edge length
l gauge length
d gauge diameter
Figure 11 — Detail Z of Figure 10
4.3 Outside-edge drop-off configuration

Terms commonly used to describe outside-edge drop-off configurations are shown in Figure 12a), 12b)

and 12c).

The outside-edge drop-off is for manufacturing purposes and is therefore a chamfer that is very small

in height but long in length.
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ISO/DIS 18669-1:2020(E)
a) Chamfered edge and drop-off b) Double-chamfered edge and c) Radiused edge and
drop-off drop-off
Key
B outside-edge drop-off length
C outside-edge drop-off height
G outside-edge chamfer length
F outside-edge length
Δ outside-edge form angle
Β outside-edge chamfer angle
Figure 12 — Drop-off configurations (detail X and Y of Figure 6)
5 Codes

Codes used for piston pins shall be as given in Table 2 with their explanatory descriptions.

Table 2 — Codes and descriptions
Relevant
subclause of
Code Description
this part of
ISO 18669

P1…P6 Pin-type classification according to manufacturing method of the pin centre hole 7.1

X Piston pins in combination with needle bearing 8.3
F1, F2, F3 Outside-edge configuration tolerance class 7.2.4
K Carburising steel class K 8.1 / 8.2
S Carburising steel class S 8.1 / 8.2
L Carburising steel class L 8.1 / 8.2
M Carburising steel class M 8.1 / 8.2
N Nitriding steel class N 8.1 / 8.2
V Piston pins with limited volume change 8.3 / 8.4 / 8.5
H1, H2 Surface hardness class 8.4
R1, R2 Peripheral surface roughness class 9.1.1
G Chamfer-locking outside-edge configuration (gauge point) 6.2 / 7.2.4
R Outside-edge radiused 7.2.4 / 6.1.2
C1 Outside-edge chamfered 7.2.4
C2 Outside-edge double chamfered 7.2.4
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ISO/DIS 18669-1:2020(E)
Table 2 (continued)
Relevant
subclause of
Code Description
this part of
ISO 18669
LA, LB Length tolerance class 7.2.3
MM Manufacturer’s mark 9.2
TC Piston pins with bore surface cold formed 7.2.6
6 Designation of piston pins
6.1 Designation elements and order

To designate piston pins, the following details shall be given, in the order shown below. The codes given

in Table 2 shall be used.
6.1.1 Mandatory elements

The following mandatory elements shall constitute the designation of a piston pin:

— designation, i.e. piston pin;
— number of International Standard: ISO 18669;
— type of piston pin, e.g. P1;
— hyphen;

— size of piston pin, d × d × l or d / d − α × d × l for a pin with tapered bore;

1 2 1 1 3 2 1
— hyphen;
— material code, e.g. L.
6.1.2 Additional elements

The following optional elements may be added to the designation of a piston pin; in this case they shall

be separated from the mandatory elements by a slash (/):
— code for outside-edge configuration, e.g. R, C1, C2, G;
— size of chamfer-locking gauge dimensions, d × l × β when code G is specified;
5 5
— code for limited volume change, V;
— code for surface hardness, H1, H2;
— code for surface roughness, R1, R2.
6.2 Designation examples

The following are examples of piston pin designation in accordance with this part of ISO 18669.

EXAMPLE 1 Designation of a piston pin complying with the requirements of ISO 18669-1, manufacturing

type P5 (P5) of outside diameter d = 20 mm (20), inside diameter d = 11 mm (11) and length l = 50 mm (50)

1 2 1

made of carburising steel, class L (L) with double chamfered outside-edge configuration (C2), selected chamfer-

locking outside-edge configuration (G) of gauge diameter d = 18,9 mm (18,9), gauge length l = 49 mm (49) and

5 5

outside-edge chamfer angle β = 45° (45), limited volume change (V), class 2 surface hardness (H2) and class 1

roughness on peripheral surface (R1). Parameters in parenthesis are used in the ISO piston pin designation:

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ISO/DIS 18669-1:2020(E)
Piston pin ISO 18669-P5, 20 × 11 × 50-L / C2 G-18,9 × 49 × 45 V H2 R1

EXAMPLE 2 Designation of a piston pin complying with the requirements of ISO 18669-1, manufacturing

type P2 (P2) of outside diameter d = 22 mm (22), tapered bore diameter d = 18 mm (18), tapered bore angle

1 3

α = 20 (20), inside diameter d = 12 mm (12) and length l = 60 mm (60) made of nitriding steel, class (N).

2 1
Parameters in parenthesis are used in the ISO piston pin designation:
Piston pin ISO 18669-P2, 22/18-20 × 12 × 60-N
7 Piston pin types, dimensions and tolerances
7.1 Manufacturing types
Table 3 — Piston pin manufacturing types
Permissible manufacturing methods
Manufacturing
cold-formed seamless
code
machined cold-formed
centre web drawn tube
P1 x x x X
P2 x x x No
P3 no x x No
P4 x x no No
P5 no x no No
P6 x no no No
7.2 Dimensions and tolerances
7.2.1 Outside diameter and form and location tolerances
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ISO/DIS 18669-1:2020(E)
a) Chamfered edge and drop-off b) Double-chamfered edge and c) Radiused edge and
drop-off drop-off
Key
B outside-edge drop-off length
C outside-edge drop-off height
F outside-edge length
G outside-edge chamfer length
Δ outside-edge form angle
Β outside-edge chamfer angle
See Figure 14.
Figure 13 — Drop-off configurations (detail X and Y of Figure 6)

Table 4 shows the outside diameter tolerances and the permissible cylindricity, circularity and edge

drop-off.
Table 4 — Outside diameter (d ) and form and location tolerances
Dimensions in millimetres
Outside diameter Edge drop-off
Cylindricity Circularity
b c
d tolerance max. max.
max. max.
8 to ≤ 16 0 to − 0,004 0,0015 0,001
> 16 to ≤ 30 0 to − 0,005 0,002 0,0015 0,12 × d 0,001
> 30 to ≤ 60 0 to − 0,006 0,0025 0,002
> 60 to ≤ 100 0 to − 0,008 0,003 0,0025 0,08 × d 0,0015
Table 5 — Waviness
Dimensions in millimetres
Sector roundness Filtered bandwidth
Dominant roundness waviness
Outside
15° 30°
diameter
(UPR 1 –50) (UPR 1 –50) (UPR 10 – 50) (UPR 10 – 50)
d max max max max
c c
8 to ≤ 16 0.0006 0.0007 0.0006 0.0006
> 16 to ≤ 30 0.0009 0.0011 0.0009 0.0009
> 30 to ≤ 60 0,0012 0.0014 0,0012 0.0012
a Other values to be agreed between customer and manufacturer
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ISO/DIS 18669-1:2020(E)
Table 5 (continued)
Sector roundness Filtered bandwidth
Dominant roundness waviness
Outside
15° 30°
diameter
(UPR 1 –50) (UPR 1 –50) (UPR 10 – 50) (UPR 10 – 50)
d max max max
max
> 60 to ≤ 100 0,0015 0,0018 0,0015 0.0015
a Other values to be agreed between customer and manufacturer
7.2.2 Inside diameter tolerance

The tolerances of inside diameter (d ) and concentricity (permissible wall difference) are shown in

...