ASTM E2905/E2905M-12
(Practice)Standard Practice for Examination of Mill and Kiln Girth Gear Teeth—Electromagnetic Methods
Standard Practice for Examination of Mill and Kiln Girth Gear Teeth—Electromagnetic Methods
SIGNIFICANCE AND USE
5.1 Visual interpretation of gear teeth condition is different from examining for cracks or early signs of macro-pitting. Visual interpretation is referred to ANSI/AGMA 1010 E-95.
5.1.1 The purpose of using eddy-current array for girth gear teeth examination is it drastically reduces examination time; covers a large area in one single pass; provides real-time cartography of the examined region, facilitating data interpretation; and improves reliability and probability of detection (POD). One tooth can be examined in less than 30 seconds.Note 2—ECA is used as a discontinuity finding tool (see Fig. 3) and a presentation aid as support once problems are discovered and photographed. As presentation is everything and so is visualization, colors and three-dimensional (3D) images (see Fig. 4) that help with visualization are absolutely invaluable in such circumstances.
5.1.2 The purpose of using alternating current field measurement is its ability to size accurately surface-breaking cracks.
5.1.3 This practice is a useful tool for a condition-based monitoring program.
5.2 The examination results may then be used by qualified personnel or organizations to assess remaining service life or other engineering characteristics (beyond the scope of this practice). This practice is not intended for the examination of non-surface-breaking discontinuities.
SCOPE
1.1 This practice describes a two-part procedure for electromagnetic evaluation on gear teeth on mill and kiln gear drives and pinions. The first part of this practice details the ability to detect 100 % of surface-breaking discontinuities only in the addendum, dedendum, and root area of the gear tooth. The second part of the examination is to have the ability to measure accurately the length and depth of any cracks found in these areas. No existing practice addresses the use of eddy current array for the detection of surface-breaking discontinuities on mill and kiln gear teeth combined with alternating current field measurement to size accurately any cracks found, length and depth.
1.2 This practice is used only for crack detection and early signs of macro-pitting. It will not illustrate a full gear tooth analysis. Visual examination by an experienced gear technician is the only way to analyze fully gear teeth wear patterns and potential failure.
1.3 Two technicians are required for this practice. One technical assistant guides the probe and the other technician operates the computer/software and analyzes the gear teeth condition.
1.4 It is important that Practice E2261 and Guides E709 accompany the technician when performing the examination.
1.5 It is recommended that the technician reviews the appendixes in this practice well in advance of starting the job.
1.6 A clean gear is recommended for a complete gear analysis. Depending on the lubrication used, the technician, in discussion with the client, shall determine what cleaning procedure should be used. If a non-asphaltic lubricant is used, ensure the gear teeth surface is clean. If an asphaltic-based lubricant is used, refer to the annexes and appendixes in this practice.
1.7 Units—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 nonconformance with the standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: E2905/E2905M − 12
StandardPractice for
Examination of Mill and Kiln Girth Gear Teeth—
Electromagnetic Methods
ThisstandardisissuedunderthefixeddesignationE2905/E2905M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 values stated in each system may not be exact equivalents;
therefore,eachsystemshallbeusedindependentlyoftheother.
1.1 This practice describes a two-part procedure for electro-
Combining values from the two systems may result in noncon-
magnetic evaluation on gear teeth on mill and kiln gear drives
formance with the standard.
and pinions. The first part of this practice details the ability to
1.8 This standard does not purport to address all of the
detect 100 % of surface-breaking discontinuities only in the
safety concerns, if any, associated with its use. It is the
addendum, dedendum, and root area of the gear tooth. The
responsibility of the user of this standard to establish appro-
secondpartoftheexaminationistohavetheabilitytomeasure
priate safety and health practices and determine the applica-
accurately the length and depth of any cracks found in these
bility of regulatory limitations prior to use.
areas. No existing practice addresses the use of eddy current
array for the detection of surface-breaking discontinuities on
2. Referenced Documents
mill and kiln gear teeth combined with alternating current field
2.1 ASTM Standards:
measurement to size accurately any cracks found, length and
E709 Guide for Magnetic Particle Testing
depth.
E1316 Terminology for Nondestructive Examinations
1.2 This practice is used only for crack detection and early
E2261 Practice for Examination of Welds Using the Alter-
signs of macro-pitting. It will not illustrate a full gear tooth
nating Current Field Measurement Technique
analysis.Visualexaminationbyanexperiencedgeartechnician
2.2 AIA Standard:
is the only way to analyze fully gear teeth wear patterns and
NAS 410 Certification and Qualification of Nondestructive
potential failure.
Test Personnel
1.3 Two technicians are required for this practice. One
2.3 ANSI/AGMA Standards:
technical assistant guides the probe and the other technician
ANSI/AGMA 1010 E-95 Standard for Appearance of Gear
operates the computer/software and analyzes the gear teeth
Teeth—Terminology of Wear and Failure
condition.
ANSI/AGMA 1012 G-05 Gear Nomenclature, Definition of
Terms
1.4 It is important that Practice E2261 and Guides E709
2.4 ANSI/ASNT Standards:
accompany the technician when performing the examination.
ANSI/ASNT-CP-189 QualificationandCertificationofNon-
1.5 It is recommended that the technician reviews the
destructive Testing Personnel
appendixes in this practice well in advance of starting the job.
SNT-TC-1A Recommended Practice Personnel Qualifica-
1.6 A clean gear is recommended for a complete gear
tion and Certification in Nondestructive Testing
analysis. Depending on the lubrication used, the technician, in
3. Terminology
discussion with the client, shall determine what cleaning
procedure should be used. If a non-asphaltic lubricant is used,
3.1 Definitions—The definitions of general terms relating to
ensure the gear teeth surface is clean. If an asphaltic-based
gear examinations can be found in Guide E709, Terminology
lubricant is used, refer to the annexes and appendixes in this
E1316, Practice E2261, ANSI/AGMA 1012 G-05, and ANSI/
practice.
AGMA 1010 E-95.
1.7 Units—The values stated in either SI units or inch-
pound units are to be regarded separately as standard. The 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
This test method is under the jurisdiction of ASTM Committee E07 on the ASTM website.
Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
Electromagnetic Method. WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
Current edition approved Nov. 15, 2012. Published November 2012. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/E2905_E2905M-12. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2905/E2905M − 12
3.2 Eddy Current Array Method: less penetration of the eddy current field into the test part
3.2.1 basic concepts of eddy current array, ECA, n—eddy allowing full coverage of any surface-breaking discontinuities
current array (ECA) technology provides the ability to drive of the component to be examined. In addition, the higher
electronicallymultipleeddycurrentcoilsplacedsidebysidein frequencies provide a higher resolution for the detection of
the same probe assembly. Data acquisition is performed by smaller defects. For this practice, a surface array probe, with
multiplexing the eddy current coils in a special pattern to avoid the ability of detecting all surface discontinuities—including
mutual inductance between the individual coils. Most conven- cracks, is required for a successful examination.
tional eddy current flaw detection techniques can be repro-
3.2.4 reference standard, n—shall contain at least one long
duced with an ECA examination. With the benefits of single-
reference indicator to standardize all the channels of the array
pass coverage, and enhanced imaging capabilities, ECA
at once and also representative defects for flaws characteriza-
technologyprovidesaremarkablypowerfultoolandsignificant
tion during the examination.
time savings during inspections. (See Fig. 1.)
3.2.5 set screws, n—conformable and substantially noncon-
3.2.1.1 Discussion—The use of eddy current array is for
ducting set screws on the probe that are used to allow small
crack detection and early signs of macro-pitting only.
liftoff adjustments or excursions on surface response.
Limitations—eddy current array will not reveal alignment
issues, backlash problems, lubrication issues, tip to root 3.2.6 system performance verification, n—use of a measure-
interface, and so forth.Visual interpretation is the method used ment of one or more physical property values for a reference
to analyze gear teeth condition. It is also very important that part to confirm that the property values are within specified
tolerances to validate the system standardization and verify
the technician has an education in gear analysis. Simple eddy
current experience does not provide the knowledge required to proper instrument operation.
interpret gear teeth issues or the understanding of ECA. The 3.2.6.1 Discussion—Probe quality—Probe life varies de-
knowledge of the defect type helps in determining the root
pending on the environmental conditions within the work area.
causes and the potential solutions, resulting in a higher Someoftheseenvironmentalfactorsaretemperature,moisture,
standard of examination.
cleanliness, and the main factor being surface roughness.
3.2.6.2 Discussion—Different equipment manufacturers
3.2.2 depth of penetration, n—eddy current density does not
may use slightly different terminology. Reference should be
remain constant across the depth of a material. The density is
made to the equipment manufacturer’s documentation for
greatest at the surface and decreases exponentially with depth
clarification.
(the “skin effect”). The standard depth of penetration equation
is used to explain the penetration capability of eddy current
3.2.7 Practice E2261—The terminology, procedure, and
testing, which decreases with increasing frequency,
definition of terms are used in this practice.
conductivity, or permeability. For a material that is both thick
NOTE 1—Different equipment manufacturers may use slightly different
and uniform, the standard depth of penetration is the depth at
terminology. Reference should be made to the equipment manufacturer’s
which the eddy current density is 37 % of the material surface
documentation for clarification.
value. To detect very shallow defects in a material, very high
3.3 ANSI/AGMA 1012 G-05—The terminology used in
frequencies are used.
ANSI/AGMA 1012 G-05 is used throughout this practice.
3.2.3 eddy current array probes, n—probes can be designed
3.4 ANSI/AGMA 1010 E-95—The terminology used in
to detect a specific type of discontinuity and to conform to the
ANSI/AGMA 1010 E-95 is used throughout this practice.
shape of the part under examination (see Fig. 2).
3.2.3.1 Discussion—Probes can be designed to detect a
4. Summary of Practice
specific type of discontinuity and conform to the shape of the
gear tooth under examination.Also notice that the center of the
4.1 Gear-Cleaning Procedure—Typically, operations does
root would actually be scanned twice. In this examination,
the cleaning or supervises the cleaning. Maintenance removes
there is no saturation performed. Surface probes are made with
the guards for access to the gear. Nondestructive evaluation
coils designed to be driven at relatively high frequencies
(NDE) girth gear examinations are provided for maintenance.
(typically 50 to 500 kHz). Using higher frequencies results in
As visual interpretation is the method used to analyze gear
teeth condition, such as contact patterns and wear patterns, a
cleaned gear is mandatory. Another reason for a cleaned gear
tooth is that it is very hard for the ECA probe to maintain the
geometry of a gear tooth that is covered with lubrication,
especially if the lubrication is asphaltic based. If asphaltic
lubrication is used, refer to Appendix X2 for cleaning proce-
dures.
4.1.1 ECA—ECA is used for nondestructively locating and
characterizing surface-breaking discontinuities in conducting
materials to electrically conductive materials. For use in this
practice,theproperlydesignedECAprobehasproventodetect
all surface-breaking discontinuities from 0.76 mm (0.03 in.)
FIG. 1 Eddy Current Single-Probe Coil Compared to Eddy Current
Array Probe Coils and larger on the addendum, dedendum, and root of girth gear
E2905/E2905M − 12
FIG. 2 Coverage of a Flexible Probe—Root, Dedendum, and Addendum
FIG. 3 Two Cracks on Tooth Just Above the Root
FIG. 4 Two- and Three-Dimensional View
teeth. The examination is performed by scanning a conform- 4.1.2 Alternating Current Field Measurement Method—
able eddy-current sensor array over the surface of the Alternating current field measurement is only to be used if a
addendum, dedendum, and root of the gear tooth being crack is found.
examined in one pass. The drive side of the tooth is referred to 4.1.3 Alternating Current Field Measurement for Nonde-
as theAside and the nondrive side of the tooth is referred to as structive Testing Detection and Sizing of Surface-Breaking
the B side of the tooth. The measured responses and location Cracks—Itworksonallmetals,ferrousornonferrous.Asensor
information are then used, typically in the form of a displayed probe is placed on the surface to be examined and an
image (C-scan), to determine the presence and characteristics alternatingcurrentisinducedintothesurface.Whennodefects
of discontinuities. arepresentthealternatingcurrentproducesauniformmagnetic
E2905/E2905M − 12
field above the surface. Any defect present will perturb the 7. Interferences—ECA
current, forcing it to flow around and underneath the defect;
7.1 Curvature of Examination Surface—For helical gears
this causes the magnetic field to become non-uniform and
with a helix angle of 1° or more, a flexible probe is required
sensors in the alternating current field measurement probe
and needs to be flexible enough to adjust its curvature to the
measure these field variations. Two components of this mag-
various helix angles. System performance verification tests
netic field are measured—one provides information about the
should be run to verify liftoff sensitivity by adjusting the set
depth or aspect ratio of the defect(s) and the other shows the
screws in the face of the array probe.
positions of the defects’ ends. The two signals are used to
7.2 Surface Conditions—Micropitting, macropitting,
confirm the presence of a defect and, together with a sizing
spalling, and so forth of gear teeth surfaces can be easily
algorithm, measure its length and depth. The main advantage
scanned with the ECA probe by adjusting the set screws
of alternating current field measurement for this practice is it
allowing for liftoff. Gear teeth surfaces shall be clean and free
provides both depth and length information. Defects up to 25
of any asphaltic lubrication.
mm (1 in.) in depth can be sized accurately.
7.3 Pressure of the Probe against Surface under
4.1.4 Magnetic Particle Examination—Magnetic particle is
Examination—Sliding the probe across the gear tooth is all the
used when a crack is found. It is used to illustrate the crack for
pressure that is required.
the picture in the report. (See Fig. 3.) It is also used when
NOTE 3—The array probe has two set screws that allow for adjusting
lift-off prevents the probe from receiving a signal.
liftoff.
7.4 Temperature—Eddy-current measurements are gener-
5. Significance and Use
ally affected by temperature variations of the material under
5.1 Visual interpretation of gear teeth condition is different
examination. For this practice, once the gear has been cleaned,
from examining for cracks or early signs of macro-pitting.
the temperature of the gear teeth is ready for examination.
Visual interpretation is referred to ANSI/AGMA 1010 E-95.
7.5 Scanning Speed—Depending on how fast a gear tooth is
5.1.1 The purpose of using eddy-current array for girth gear
scanned, C-scans will be more or less long, which means that
teeth examination is it drastically reduces examination time;
they will contain also more or less acquisitions points. As the
covers a large area in one single pass; provides real-time
technician applies a filter with a given number of points on the
cartography of the examined region, facilitating data interpre-
C-scan, this filter could cut or modify some indications.
tation; and improves reliability and probability of detection
Scanning speed should be at the same speed that is set in the
(POD). One tooth can be examined in less than 30 seconds.
scan parameters.
NOTE 2—ECAis used as a discontinuity finding tool (see Fig. 3) and a
7.6 Residual Magnetism—In magnetic materi
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