ASTM A456/A456M-08(2023)
(Specification)Standard Specification for Magnetic Particle Examination of Large Crankshaft Forgings
Standard Specification for Magnetic Particle Examination of Large Crankshaft<brk/> Forgings
ABSTRACT
This test method deals with the acceptance criteria for the magnetic particle examination of forged steel crankshafts and forgings having large main bearing journal or crankpin diameters. Covered here are three classes of forgings, which shall be evaluated under two areas of inspection, namely: major critical areas, and minor critical areas. During inspection, magnetic particle indications shall be classified as: surface indications, which include nonmetallic inclusions or stringers, open or twist cracks, flakes, or pipes; open or pinpoint indications; and non-open indications. Procedures for dimpling, depressing, inspection, and product marking are also mentioned.
SCOPE
1.1 This is an acceptance specification for the magnetic particle inspection of forged steel crankshafts having main bearing journals or crankpins 4 in. [200 mm] or larger in diameter.
1.2 There are three classes, with acceptance standards of increasing severity:
1.2.1 Class 1.
1.2.2 Class 2 (originally the sole acceptance standard of this specification).
1.2.3 Class 3 (formerly covered in Supplementary Requirement S1 of Specification A456 – 64 (1970)).
1.3 This specification is not intended to cover continuous grain flow crankshafts (see Specification A983/A983M); however, Specification A986/A986M may be used for this purpose.
Note 1: Specification A668/A668M is a product specification which may be used for slab-forged crankshaft forgings that are usually twisted in order to set the crankpin angles, or for barrel forged crankshafts where the crankpins are machined in the appropriate configuration from a cylindrical forging.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch units.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A456/A456M − 08 (Reapproved 2023)
Standard Specification for
Magnetic Particle Examination of Large Crankshaft
Forgings
This standard is issued under the fixed designation A456/A456M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This is an acceptance specification for the magnetic
particle inspection of forged steel crankshafts having main
2. Referenced Documents
bearing journals or crankpins 4 in. [200 mm] or larger in
diameter.
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of
1.2 There are three classes, with acceptance standards of
Steel Forgings
increasing severity:
A668/A668M Specification for Steel Forgings, Carbon and
1.2.1 Class 1.
Alloy, for General Industrial Use
1.2.2 Class 2 (originally the sole acceptance standard of this
A966/A966M Practice for Magnetic Particle Examination of
specification).
Steel Forgings Using Alternating Current
1.2.3 Class 3 (formerly covered in Supplementary Require-
A983/A983M Specification for Continuous Grain Flow
ment S1 of Specification A456 – 64 (1970)).
Forged Carbon and Alloy Steel Crankshafts for Medium
1.3 This specification is not intended to cover continuous
Speed Diesel Engines
grain flow crankshafts (see Specification A983/A983M);
A986/A986M Specification for Magnetic Particle Examina-
however, Specification A986/A986M may be used for this
tion of Continuous Grain Flow Crankshaft Forgings
purpose.
E1417/E1417M Practice for Liquid Penetrant Testing
NOTE 1—Specification A668/A668M is a product specification which
may be used for slab-forged crankshaft forgings that are usually twisted in
3. Classification of Indications
order to set the crankpin angles, or for barrel forged crankshafts where the
crankpins are machined in the appropriate configuration from a cylindrical
3.1 Magnetic particle indications on the surface of the
forging.
crankshaft shall be classified as follows:
1.4 The values stated in either SI units or inch-pound units
3.1.1 Open cracks, flake, or pipe.
are to be regarded separately as standard. The values stated in
3.1.2 Nonmetallic inclusions or stringers occurring in a
each system may not be exact equivalents; therefore, each
longitudinal direction.
system shall be used independently of the other. Combining
3.1.3 Twist cracks or nonmetallic inclusions usually occur-
values from the two systems may result in non-conformance
ring at 45 to 70° from the axis of the journal.
with the standard.
3.2 They shall also be classified as follows:
1.5 Unless the order specifies the applicable “M” specifica-
3.2.1 Open indications are visible after removal of the
tion designation, the material shall be furnished to the inch
magnetic particles or can be detected by the use of contrast dye
units.
penetrant, as described in Type II of Practice E1417/E1417M.
1.6 This international standard was developed in accor-
3.2.1.1 Pinpoint indications are open indications ⁄16 in.
dance with internationally recognized principles on standard-
[1.5 mm] in maximum dimension, as detected by application of
ization established in the Decision on Principles for the
Type II of Practice E1417/E1417M.
Development of International Standards, Guides and Recom-
3.2.2 Non-open indications are indications which are not
visually detectable as described in 3.2.1.
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys, and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2023. Published April 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2018 as A456/A456M – 08 Standards volume information, refer to the standard’s Document Summary page on
(2018). DOI: 10.1520/A0456_A0456M-08R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A456/A456M − 08 (2023)
4. Ordering Information 6.1.3 The critical area of any crankpin or main journal also
includes that surface area closer than ⁄4 in. [6 mm] to the
4.1 The inquiry and purchase agreement shall contain a
junction of the radius blend and the journal surface of any oil
statement that the crankshaft(s) is (are) to be subject to
hole.
acceptance according to this specification. If reference to class
is omitted, Class 2 shall apply. 6.2 Minor Critical Areas—Minor critical areas include all
machined fillets, thrust bearing, and bearing surfaces not
4.2 The use of Supplementary Requirements S1 and S2
specified as major critical areas.
should be specified if required.
7. Acceptance Standards
5. Procedure
7.1 Class 1:
5.1 Magnetic particle inspection shall be conducted accord-
7.1.1 Major Critical Areas:
ing to Practice A966/A966M, except when Supplementary 1
7.1.1.1 Open indications over ⁄4 in. [6 mm] in length shall
Requirement S1 is to be used. The use of prod type contacts is
be removed by dimpling to a depth no greater than ⁄16 in.
not permitted on finished crankshafts. Magnetic leeches may
1 1
[5 mm]. Open indications over ⁄16 in. to ⁄4 in. [1.5 mm to 6
only be used on noncritical parts of the crankshaft when
mm] in length shall be depressed as in 7.2.2.3.
Supplementary Requirement S2 is utilized.
7.1.1.2 Pinpoint indications are permissible, except in clus-
1 1
ters of more than 5 in any ⁄4-in. by ⁄4-in. [6-mm by 6-mm]
6. Areas of Inspection
area, in which case they must be dimpled to a depth of no more
6.1 Major Critical Areas: than ⁄16 in. [5 mm]. If they do not open or increase in number
6.1.1 The critical area of any crankpin shall be that area plus they are acceptable and need not be removed.
or minus 60° from the 6 o’clock position of the pin extending 7.1.1.3 Non-open indications are acceptable up to and
3 1
⁄8 in. [10 mm] above the thrust collar around the fillet, and including ⁄2 in. [13 mm] in length. If non-open indications are
5 1
⁄8 in. [16 mm] into the pin along its axis measured from over ⁄2 in. [13 mm], depress, and if they are not open or are
approximately the blend of the pin surface and fillet, as shown worsening, accept them. Otherwise remove by dimpling to a
in Fig. 1 and Fig. 2. maximum depth of ⁄16 in. [5 mm].
6.1.2 The critical areas of any main bearing journal shall be 7.1.1.4 The total area of dimples shall be limited as in
that area plus or minus 60° from the 12 o’clock position on top 7.2.1.3.
of the journal extending ⁄8 in. [10 mm] above the thrust collar 7.1.2 Minor Critical Areas:
around the fillet and ⁄8 in. [16 mm] into the journal along its 7.1.2.1 Open indications oriented at an angle in excess of
axis measured from approximately the blend of the journal 30° to the longitudinal axis must be removed to a depth not
surface and the fillet, as shown in Fig. 1 and Fig. 2. exceeding ⁄16 in. [5 mm], by dimpling.
Metric Equivalents
3 5
⁄8 in. = [10 mm] ⁄8 in. = [16 mm]
FIG. 1 Critical Surface Areas of Crankpin and Main Bearing Journal
A456/A456M − 08 (2023)
(1)— ⁄8 in. [16 mm] on pin or journal,
(2)—Fillet radius, R,
(3)—Thrust collar, and
(4)— ⁄8 –in. [10-mm] ring beyond thrust collar.
NOTE 1—The critical area is 120° on the pin or journal.
FIG. 2 Reference Dimensions for Calculations
1 3
7.1.2.2 Open indications longer than 1 ⁄2 in. [38 mm] dimpled to a depth of ⁄16 in. [5 mm] and reduced to no more
individually or more than 3 in. [75 mm] of total length per than three pinpoints unless they are removed at a lesser depth.
bearing journal, that are parallel to the longitudinal axis within
If no more than three pinpoints remain at the ⁄16-in. [5-mm]
30°, must be removed by dimpling to a depth no greater than
depth, they are acceptable and need not be removed.
⁄16 in. [5 mm]. Intermittent open indications in a line, spaced
7.2.1.2 Magnetic particle buildup exceeding ⁄4 in. [6 mm]
less than ⁄4 in. [6 mm] apart, shall be considered continuous or
in length and which has been found to be non-open by the
as one indication.
procedure described in 3.2.1 shall be jointly investigated by the
1 1
7.1.2.3 Open indications ⁄8 in. [3 mm] to 1 ⁄2 in. [38 mm]
manufacturer and purchaser, or their representatives.
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: A456/A456M − 08 (Reapproved 2023)
Standard Specification for
Magnetic Particle Examination of Large Crankshaft
Forgings
This standard is issued under the fixed designation A456/A456M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This is an acceptance specification for the magnetic
particle inspection of forged steel crankshafts having main
2. Referenced Documents
bearing journals or crankpins 4 in. [200 mm] or larger in
diameter.
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of
1.2 There are three classes, with acceptance standards of
Steel Forgings
increasing severity:
A668/A668M Specification for Steel Forgings, Carbon and
1.2.1 Class 1.
Alloy, for General Industrial Use
1.2.2 Class 2 (originally the sole acceptance standard of this
A966/A966M Practice for Magnetic Particle Examination of
specification).
Steel Forgings Using Alternating Current
1.2.3 Class 3 (formerly covered in Supplementary Require-
A983/A983M Specification for Continuous Grain Flow
ment S1 of Specification A456 – 64 (1970)).
Forged Carbon and Alloy Steel Crankshafts for Medium
1.3 This specification is not intended to cover continuous
Speed Diesel Engines
grain flow crankshafts (see Specification A983/A983M);
A986/A986M Specification for Magnetic Particle Examina-
however, Specification A986/A986M may be used for this
tion of Continuous Grain Flow Crankshaft Forgings
purpose.
E1417/E1417M Practice for Liquid Penetrant Testing
NOTE 1—Specification A668/A668M is a product specification which
may be used for slab-forged crankshaft forgings that are usually twisted in
3. Classification of Indications
order to set the crankpin angles, or for barrel forged crankshafts where the
crankpins are machined in the appropriate configuration from a cylindrical
3.1 Magnetic particle indications on the surface of the
forging.
crankshaft shall be classified as follows:
1.4 The values stated in either SI units or inch-pound units
3.1.1 Open cracks, flake, or pipe.
are to be regarded separately as standard. The values stated in
3.1.2 Nonmetallic inclusions or stringers occurring in a
each system may not be exact equivalents; therefore, each
longitudinal direction.
system shall be used independently of the other. Combining
3.1.3 Twist cracks or nonmetallic inclusions usually occur-
values from the two systems may result in non-conformance
ring at 45 to 70° from the axis of the journal.
with the standard.
3.2 They shall also be classified as follows:
1.5 Unless the order specifies the applicable “M” specifica-
3.2.1 Open indications are visible after removal of the
tion designation, the material shall be furnished to the inch
magnetic particles or can be detected by the use of contrast dye
units.
penetrant, as described in Type II of Practice E1417/E1417M.
1.6 This international standard was developed in accor-
3.2.1.1 Pinpoint indications are open indications ⁄16 in.
dance with internationally recognized principles on standard-
[1.5 mm] in maximum dimension, as detected by application of
ization established in the Decision on Principles for the
Type II of Practice E1417/E1417M.
Development of International Standards, Guides and Recom-
3.2.2 Non-open indications are indications which are not
visually detectable as described in 3.2.1.
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys, and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2023. Published April 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2018 as A456/A456M – 08 Standards volume information, refer to the standard’s Document Summary page on
(2018). DOI: 10.1520/A0456_A0456M-08R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A456/A456M − 08 (2023)
4. Ordering Information 6.1.3 The critical area of any crankpin or main journal also
includes that surface area closer than ⁄4 in. [6 mm] to the
4.1 The inquiry and purchase agreement shall contain a
junction of the radius blend and the journal surface of any oil
statement that the crankshaft(s) is (are) to be subject to
hole.
acceptance according to this specification. If reference to class
is omitted, Class 2 shall apply. 6.2 Minor Critical Areas—Minor critical areas include all
machined fillets, thrust bearing, and bearing surfaces not
4.2 The use of Supplementary Requirements S1 and S2
specified as major critical areas.
should be specified if required.
7. Acceptance Standards
5. Procedure
7.1 Class 1:
5.1 Magnetic particle inspection shall be conducted accord-
7.1.1 Major Critical Areas:
ing to Practice A966/A966M, except when Supplementary
7.1.1.1 Open indications over ⁄4 in. [6 mm] in length shall
Requirement S1 is to be used. The use of prod type contacts is 3
be removed by dimpling to a depth no greater than ⁄16 in.
not permitted on finished crankshafts. Magnetic leeches may
1 1
[5 mm]. Open indications over ⁄16 in. to ⁄4 in. [1.5 mm to 6
only be used on noncritical parts of the crankshaft when
mm] in length shall be depressed as in 7.2.2.3.
Supplementary Requirement S2 is utilized.
7.1.1.2 Pinpoint indications are permissible, except in clus-
1 1
ters of more than 5 in any ⁄4-in. by ⁄4-in. [6-mm by 6-mm]
6. Areas of Inspection
area, in which case they must be dimpled to a depth of no more
6.1 Major Critical Areas: than ⁄16 in. [5 mm]. If they do not open or increase in number
6.1.1 The critical area of any crankpin shall be that area plus they are acceptable and need not be removed.
or minus 60° from the 6 o’clock position of the pin extending 7.1.1.3 Non-open indications are acceptable up to and
3 1
⁄8 in. [10 mm] above the thrust collar around the fillet, and including ⁄2 in. [13 mm] in length. If non-open indications are
5 1
⁄8 in. [16 mm] into the pin along its axis measured from over ⁄2 in. [13 mm], depress, and if they are not open or are
approximately the blend of the pin surface and fillet, as shown worsening, accept them. Otherwise remove by dimpling to a
in Fig. 1 and Fig. 2. maximum depth of ⁄16 in. [5 mm].
6.1.2 The critical areas of any main bearing journal shall be 7.1.1.4 The total area of dimples shall be limited as in
that area plus or minus 60° from the 12 o’clock position on top 7.2.1.3.
of the journal extending ⁄8 in. [10 mm] above the thrust collar 7.1.2 Minor Critical Areas:
around the fillet and ⁄8 in. [16 mm] into the journal along its 7.1.2.1 Open indications oriented at an angle in excess of
axis measured from approximately the blend of the journal 30° to the longitudinal axis must be removed to a depth not
surface and the fillet, as shown in Fig. 1 and Fig. 2. exceeding ⁄16 in. [5 mm], by dimpling.
Metric Equivalents
3 5
⁄8 in. = [10 mm] ⁄8 in. = [16 mm]
FIG. 1 Critical Surface Areas of Crankpin and Main Bearing Journal
A456/A456M − 08 (2023)
(1)— ⁄8 in. [16 mm] on pin or journal,
(2)—Fillet radius, R,
(3)—Thrust collar, and
(4)— ⁄8 –in. [10-mm] ring beyond thrust collar.
NOTE 1—The critical area is 120° on the pin or journal.
FIG. 2 Reference Dimensions for Calculations
1 3
7.1.2.2 Open indications longer than 1 ⁄2 in. [38 mm] dimpled to a depth of ⁄16 in. [5 mm] and reduced to no more
individually or more than 3 in. [75 mm] of total length per
than three pinpoints unless they are removed at a lesser depth.
bearing journal, that are parallel to the longitudinal axis within If no more than three pinpoints remain at the ⁄16-in. [5-mm]
30°, must be removed by dimpling to a depth no greater than
depth, they are acceptable and need not be removed.
⁄16 in. [5 mm]. Intermittent open indications in a line, spaced 1
7.2.1.2 Magnetic particle buildup exceeding ⁄4 in. [6 mm]
less than ⁄4 in. [6 mm] apart, shall be considered continuous or
in length and which has been found to be non-open by the
as one indication.
procedure described in 3.2.1 shall be jointly investigated by the
1 1
7.1.2.3 Open indications ⁄8 in. [3 mm] to 1 ⁄2 in. [38 mm]
manufacturer and purchaser, or their representatives. Each
long, with the exception of those referred to in 7.1.2.1, shall
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A456/A456M − 08 (Reapproved 2018) A456/A456M − 08 (Reapproved 2023)
Standard Specification for
Magnetic Particle Examination of Large Crankshaft
Forgings
This standard is issued under the fixed designation A456/A456M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This is an acceptance specification for the magnetic particle inspection of forged steel crankshafts having main bearing
journals or crankpins 4 in. [200 mm] or larger in diameter.
1.2 There are three classes, with acceptance standards of increasing severity:
1.2.1 Class 1.
1.2.2 Class 2 (originally the sole acceptance standard of this specification).
1.2.3 Class 3 (formerly covered in Supplementary Requirement S1 of Specification A456 – 64 (1970)).
1.3 This specification is not intended to cover continuous grain flow crankshafts (see Specification A983/A983M); however,
Specification A986/A986M may be used for this purpose.
NOTE 1—Specification A668/A668M is a product specification which may be used for slab-forged crankshaft forgings that are usually twisted in order
to set the crankpin angles, or for barrel forged crankshafts where the crankpins are machined in the appropriate configuration from a cylindrical forging.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.5 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch units.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys, and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved March 1, 2018March 15, 2023. Published March 2018April 2023. Originally approved in 1999. Last previous edition approved in 20132018 as
A456/A456M – 08 (2013).(2018). DOI: 10.1520/A0456_A0456M-08R18.10.1520/A0456_A0456M-08R23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A456/A456M − 08 (2023)
2. Referenced Documents
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A668/A668M Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use
A966/A966M Practice for Magnetic Particle Examination of Steel Forgings Using Alternating Current
A983/A983M Specification for Continuous Grain Flow Forged Carbon and Alloy Steel Crankshafts for Medium Speed Diesel
Engines
A986/A986M Specification for Magnetic Particle Examination of Continuous Grain Flow Crankshaft Forgings
E1417/E1417M Practice for Liquid Penetrant Testing
3. Classification of Indications
3.1 Magnetic particle indications on the surface of the crankshaft shall be classified as follows:
3.1.1 Open cracks, flake, or pipe.
3.1.2 Nonmetallic inclusions or stringers occurring in a longitudinal direction.
3.1.3 Twist cracks or nonmetallic inclusions usually occurring at 45 to 70° from the axis of the journal.
3.2 They shall also be classified as follows:
3.2.1 Open indications are visible after removal of the magnetic particles or can be detected by the use of contrast dye penetrant,
as described in Type II of Practice E1417/E1417M.
3.2.1.1 Pinpoint indications are open indications ⁄16 in. [1.5 mm] in maximum dimension, as detected by application of Type II
of Practice E1417/E1417M.
3.2.2 Non-open indications are indications which are not visually detectable as described in 3.2.1.
4. Ordering Information
4.1 The inquiry and purchase agreement shall contain a statement that the crankshaft(s) is (are) to be subject to acceptance
according to this specification. If reference to class is omitted, Class 2 shall apply.
4.2 The use of Supplementary Requirements S1 and S2 should be specified if required.
5. Procedure
5.1 Magnetic particle inspection shall be conducted according to Practice A966/A966M, except when Supplementary
Requirement S1 is to be used. The use of prod type contacts is not permitted on finished crankshafts. Magnetic leeches may only
be used on noncritical parts of the crankshaft when Supplementary Requirement S2 is utilized.
6. Areas of Inspection
6.1 Major Critical Areas:
6.1.1 The critical area of any crankpin shall be that area plus or minus 60° from the 6 o’clock position of the pin extending ⁄8
in. in. [10 mm] above the thrust collar around the fillet, and ⁄8 in. in. [16 mm] into the pin along its axis measured from
approximately the blend of the pin surface and fillet, as shown in Fig. 1 and Fig. 2.
6.1.2 The critical areas of any main bearing journal shall be that area plus or minus 60° from the 12 o’clock position on top of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
A456/A456M − 08 (2023)
Metric Equivalents
3 5
⁄8 in. = [10 mm] ⁄8 in. = [16 mm]
FIG. 1 Critical Surface Areas of Crankpin and Main Bearing Journal
(1)— ⁄8 in. [16 mm] on pin or journal,
(2)—Fillet radius, R,
(3)—Thrust collar, and
(4)— ⁄8 –in. [10-mm] ring beyond thrust collar.
NOTE 1—The critical area is 120° on the pin or journal.
FIG. 2 Reference Dimensions for Calculations
3 5
the journal extending ⁄8 in. [10 mm] above the thrust collar around the fillet and ⁄8 in. in. [16 mm] into the journal along its axis
measured from approximately the blend of the journal surface and the fillet, as shown in Fig. 1 and Fig. 2.
6.1.3 The critical area of any crankpin or main journal also includes that surface area closer than ⁄4 in. in. [6 mm] to the junction
of the radius blend and the journal surface of any oil hole.
6.2 Minor Critical Areas—Minor critical areas include all machined fillets, thrust bearing, and bearing surfaces not specified as
major critical areas.
A456/A456M − 08 (2023)
7. Acceptance Standards
7.1 Class 1:
7.1.1 Major Critical Areas:
1 3
7.1.1.1 Open indications over ⁄4 in. [6 mm] in length shall be removed by dimpling to a depth no greater than ⁄16 in. [5 mm]. Open
1 1
indications over ⁄16 in. to ⁄4 in. [1.5[1.5 mm to 6 mm] in length shall be depressed as in 7.2.2.3.
1 1
7.1.1.2 Pinpoint indications are permissible, except in clusters of more than 5 in any ⁄4-in. by ⁄4-in. [6[6-mm by 6-mm] area, in
which case they must be dimpled to a depth of no more than ⁄16 in. [5 mm]. If they do not open or increase in number they are
acceptable and need not be removed.
1 1
7.1.1.3 Non-open indications are acceptable up to and including ⁄2 in. in. [13 mm] in length. If non-open indications are over ⁄2
in. [13 mm], depress, and if they are not open or are worsening, accept them. Otherwise remove by dimpling to a maximum depth
of ⁄16 in. [5 mm].
7.1.1.4 The total area of dimples shall be limited as in 7.2.1.3.
7.1.2 Minor Critical Areas:
7.1.2.1 Open indications oriented at an angle in excess of 30° to the longitudinal axis must be removed to a depth not exceeding
⁄16 in. [5 mm], by dimpling.
7.1.2.2 Open indications longer than 1 ⁄2 in. [38 mm] individually or more than 3 in. [75 mm] of total length per bearing journal,
that are parallel to the longitudinal axis within 30°, must be removed by dimpling to a depth no greater than ⁄16 in. [5 mm].
Intermittent open indications in a line, spaced less than ⁄4 in. [6 mm] apart, shall be considered continuous or as one indication.
1 1
7.1.2.3 Open indications ⁄8 in. [3 mm] to 1 ⁄2 in. [38 mm] long, with the exception of those referred to in 7.1.2.1, shall be
depressed 0.0030.003 in. to 0.010 in. [0.05[0.05 mm to 0.25 mm] below the surface but need not be removed.
7.1.2.4 Open indications less than ⁄8 in. [3 mm] long need not be depressed, dimpled, or removed.
7.1.2.5 A cluster of open indications, with the exception of those referred to in 7.1.2.1, having a total length n
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