ISO 6624-1:2001

INTERNATIONAL ISO
STANDARD 6624-1
Second edition
2001-08-01
Internal combustion engines —
Piston rings —
Part 1:
Keystone rings made of cast iron
Moteurs à combustion interne — Segments de piston —
Partie 1: Segments trapézoïdaux en fonte
Reference number
ISO 6624-1:2001(E)
©
ISO 2001

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ISO 6624-1:2001(E)
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ii © ISO 2001 – All rights reserved

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ISO 6624-1:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative reference .1
3 Overview.1
4 Ring types and designation examples .2
4.1 Type T — Straight faced keystone ring 6°.2
4.2 Type TB — Symmetrical barrel faced keystone ring 6° .4
4.3 Type TBA — Asymmetrical barrel faced keystone ring 6° .6
4.4 Type TM — Taper faced keystone ring 6° .8
4.5 Type K — Straight faced keystone ring 15° .9
4.6 Type KB — Symmetrical barrel faced keystone ring 15°.10
4.7 Type KBA — Asymmetrical barrel faced keystone ring 15°.11
4.8 Type KM — Taper faced keystone ring 15°.12
5 Common features .13
5.1 Type T, TB, TBA, TM, K, KB, KBA, KM rings — Inside chamfered edges (KI).13
5.2 Type T, TB, TBA, TM, K, KB, KBA, KM rings (positive twist type) internal bevel or internal step
top side .13
5.3 Type TM or KM rings with partly cylindrical machined (LM) or lapped (LP) peripheral surface.14
5.4 Type T, TB, TBA, TM, K, KB, KBA, KM rings — Plating/coating configuration.15
6 Force Factors .17
7 Dimensions.18
Bibliography.26
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ISO 6624-1:2001(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 6624 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 6624-1 was prepared by Technical Committee ISO/TC 22, Road vehicles.
This second edition cancels and replaces the first edition (ISO 6624-1:1986), which has been technically revised.
ISO 6624 consists of the following parts, under the general title Internal combustion engines — Piston rings:
� Part 1: Keystone rings made of cast iron
� Part 2: Half keystone rings made of cast iron
� Part 3: Keystone rings made of steel
� Part 4: Half keystone rings made of steel
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ISO 6624-1:2001(E)
Introduction
ISO 6624 is one of a number of series of International Standards dealing with piston rings for reciprocating internal
combustion engines. Others are ISO 6621, ISO 6622, ISO 6623, ISO 6625, ISO 6626 and ISO 6627 (see
Bibliography for details).
The common features and dimensional tables presented in this part of ISO 6624 constitute a broad range of
variables and, in selecting a particular ring type, the designer must bear in mind the conditions under which it will
be required to operate.
[4]
It is also essential that the designer refer to the specifications and requirements of ISO 6621-3 and ISO 6621-4
before completing a selection.
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INTERNATIONAL STANDARD ISO 6624-1:2001(E)
Internal combustion engines — Piston rings —
Part 1:
Keystone rings made of cast iron
1 Scope
This part of ISO 6624 specifies the essential dimensional features of keystone rings made of cast iron, types T, TB,
TBA, TM, K, KB, KBA and KM, having diameters of from 70 mm up to and including 200 mm, used in reciprocating
internal combustion piston engines.
2 Normative reference
The following normative document contain provisions which, through reference in this text, constitute provisions of
this part of ISO 6624. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 6624 are encouraged to investigate the
possibility of applying the most recent edition of the normative document indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
1)
ISO 6621-4:— , Internal combustion engines — Piston rings — Part 4: General specifications.
3Overview
The keystone ring types are specified in Tables 1 to 3 and Figures 1 to 8. Their common features and the
dimensions of those features are specified in Tables 4 to 7 and Figures 9 to 16. Tables 8 and 9 give the force
factors for the different types of ring, while Table 10 and Table 11 give the dimensions and forces of keystone rings
6� and 15�, respectively.
1) To be published. (Revision of ISO 6621-4:1988)
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ISO 6624-1:2001(E)
4 Ring types and designation examples
4.1 Type T — Straight faced keystone ring 6°
4.1.1 General features
See Table 10 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 1 — Type T
4.1.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 6° keystone ring
with a straight faced peripheral surface (T), of nominal diameter d � 90 mm (90) and nominal width h � 2,5 mm (2,5), made of
1 1
grey cast iron, subclass 12 (MC12), and having a chromium plated peripheral surface with a minimum thickness of 0,1 mm
(CR2):
Piston ring ISO 6624-1 T- 90 �� 2,5-MC12/CR2
��
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ISO 6624-1:2001(E)
(blank page)
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ISO 6624-1:2001(E)
4.2 Type TB — Symmetrical barrel faced keystone ring 6°
4.2.1 General features
See Table 10 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 2 — Type TB
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ISO 6624-1:2001(E)
Table 1 — Symmetrical barrel dimensions
Dimensions in millimetres
a
h h h h t , t
h
1 25 26 27 2 3
8
Tolerance
2,0 0,40 1,00 1,60 1,2
� 0,30
0,003.0,015
2,5 0,45 1,25 2,05 1,6
� 0,40
3,0 0,50 1,50 2,50 2,0
� 0,50 0,005.0,020
3,5 0,55 1,75 2,95 2,4
4,0 0,60 2,00 3,40 2,8
� 0,60 0,005.0,023
4,5 0,65 2,25 3,85 3,2
a
Gauge width h , informative only, shall be used only if agreed between manufacturer and client.
8
4.2.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 6° keystone ring
with a symmetrical barrel faced peripheral surface (TB), of nominal diameter d � 90 mm (90) and nominal ring width
1
h � 2,5 mm (2,5), made of heat-treated martensitic spheroidal graphite cast iron, subclass 53 (MC53), and having a semi-inlaid
1
spray coating on the peripheral surface with a minimum thickness of 0,2 mm (SC4E):
Piston ring ISO 6624-1 TB - 90 �� 2,5-MC53/SC4E
��
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ISO 6624-1:2001(E)
4.3 Type TBA — Asymmetrical barrel faced keystone ring 6°
4.3.1 General features
See Table 10 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
2Mark
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 3 — Type TBA
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ISO 6624-1:2001(E)
Table 2 — Asymmetrical barrel dimensions
Dimensions in millimetres
a b b
h h h
h t t
1 26 27
25 2 3
Tolerance
2,00 0,40 0,60 1,50 0.0,007 0,009.0,030
� 0,20
2,50 0,45 0,70 1,80 0,011.0,035
� 0,25 0.0,008
3,00 0,55 0,80 2,10 0,012.0,038
3,50 0,60 0,90 2,40 0,012.0,040
� 0,30 0.0,009
4,00 0,65 0,95 2,80 0,013.0,045
4,50 0,70 1,05 3,20 0.0,010 0,015.0,050
� 0,35
a
h may be lowered for rings with reduced edge dimensions.
25
b
t or t or both may be varied as agreed between manufacturer and client.
2 3
4.3.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 6° keystone ring
with an asymmetrical barrel faced peripheral surface (TBA), of nominal diameter d � 90 mm (90) and nominal ring width
1
h � 2,5 mm (2,5), made of heat-treated martensitic spheroidal graphite cast iron, subclass 53 (MC53), and having a semi-inlaid
1
spray coating on the peripheral surface with a minimum thickness of 0,2 mm (SC4E):
Piston ring ISO 6624-1 TBA - 90 ���� 2,5-MC53/SC4E
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ISO 6624-1:2001(E)
4.4 Type TM — Taper faced keystone ring 6°
4.4.1 General features
See Table 10 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
2Mark
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 4 — Type TM
Table 3 — Taper
Dimensions in minutes
Internal twist feature designs
a
Code Taper Tolerance
a
Tolerance
�50 �60
b
10
M1 0 0
M2 30
M3 60
�60 �70
0 0
M4 90
M5 120
a
For chromium plated rings with a tapered peripheral surface that is not ground, the tolerance shall be
�70 �80
increased by 10 (e.g. M3 � 60 tolerance: ; M3 with internal features � 60 tolerance: ).
0 0
b
M1 not for rings with partly cylindrical peripheral surface.
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ISO 6624-1:2001(E)
4.4.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 6° keystone ring
witha10´ taper faced peripheral surface (TM1), of nominal diameter d � 90 mm (90) and nominal ring width h � 2,5 mm (2,5),
1 1
made of heat-treated grey cast iron, subclass 22 (MC22), and phosphate-coated all over (PO):
Piston ring ISO 6624-1 TM1 - 90 �� 2,5-MC22/PO
��
4.5 Type K — Straight faced keystone ring 15°
4.5.1 General features
See Table 11 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 5 — Type K
4.5.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 15° keystone
ring with a straight faced peripheral surface (K), of nominal diameter d � 90 mm (90) and nominal ring width h � 2,5 mm (2,5),
1 1
made of carbidic cast iron, subclass 32 (MC32), and ferroxide coated all over (FE):
Piston ring ISO 6624-1 K - 90 ���� 2,5-MC32/FE
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ISO 6624-1:2001(E)
4.6 Type KB — Symmetrical barrel faced keystone ring 15°
4.6.1 General features
See Table 1 for symmetrical barrel dimensions.
See Table 11 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 6 — Type KB
4.6.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 15° keystone
ring with a barrel faced peripheral surface (KB), of nominal diameter d � 90 mm (90) and nominal ring width h � 2,5 mm (2,5),
1 1
made of malleable cast iron, subclass 4l (MC4l), and having an inlaid spray coating on the peripheral surface with a minimum
thickness of 0,2 mm (SC4F):
Piston ring ISO 6624-1 KB - 90 �� 2,5-MC41/SC4F
��
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ISO 6624-1:2001(E)
4.7 Type KBA — Asymmetrical barrel faced keystone ring 15°
4.7.1 General features
See Table 2 for asymmetrical barrel dimensions.
See Table 11 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
2Mark
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 7 — Type KBA
4.7.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron 15° keystone
ring with an asymmetrical barrel faced peripheral surface (KBA) of nominal diameter d � 90 mm (90) and nominal ring width
1
h � 2,5 mm (2,5), made of malleable cast iron, subclass 4l (MC4l), and having an inlaid spray coating on the peripheral surface
1
with a minimum thickness of 0,2 mm (SC4F):
Piston ring ISO 6624-1 KBA - 90 ���� 2,5-MC41/SC4F
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ISO 6624-1:2001(E)
4.8 Type KM — Taper faced keystone ring 15°
4.8.1 General features
See Table 3 for taper.
See Table 11 for dimensions and forces.
Dimensions in millimetres
Key
1 Reference plane
2Mark
a
Due to manufacturing processing, side angle tolerances are not cumulative.
b
Nominal.
Figure 8 — Type KM
4.8.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of ISO 6624-1, being a cast iron, 15° keystone
ring with a 10´ taper faced peripheral surface (KM1), of nominal diameter d � 90 mm (90) and nominal ring width h � 2,5 mm
1 1
(2,5), made of grey cast iron, subclass 12 (MC12):
Piston ring ISO 6624-1 KM1 - 90 ���� 2,5-MC12
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ISO 6624-1:2001(E)
5 Common features
5.1 Type T, TB, TBA, TM, K, KB, KBA, KM rings — Inside chamfered edges (KI)
Figure 9 — Inside chamfered edges (KI)
Table 4 — KI dimensions
Dimensions in millimetres
d KI
1
70u d � 125 0,3 � 0,15
1
125u d � 175 0,4 � 0,15
1
175u d u 200 0,6 � 0,20
1
5.2 Type T, TB, TBA, TM, K, KB, KBA, KM rings (positive twist type) internal bevel or internal
step top side
An internal bevel is not recommended for the 15° keystone rings with ring width h given in the “nominal value of
1
ring width” column 1 of Table 11.
Dimensions in millimetres
Key
1Mark
Figure 11 — Internal step top side (IW)
Figure 10 — Internal bevel top side (IF)
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ISO 6624-1:2001(E)
Table 5 — a and h dimensions
3 18
Dimensions in millimetres
d a h
1 3 18
Tolerance Tolerance
0 0
...