Standard Practices Calibration Laboratory
Gleason Metrology Systems
v004, Feb 11, 2021

Standard Practices Calibration Laboratory
GeneralThe Gleason Metrology Systems Calibration Laboratory (Lab) provides services based on
the following Standard Practices unless the Customer and the Lab have agreed to different procedures. Lab Customers are strongly encouraged to review the quotation and thisinformation concerning Standard Practices in detail before issuing purchase orders forcalibration or inspection services.
Scope of Work
The Lab has set limits upon its scope of standard work. Quotations for calibration or inspection services within this scope can usually be prepared according to a standard pricelist. When requested calibration or inspection services are beyond this scope, the Lab
may either decline to quote or provide a special quotation according to the particulars of
the application.
The Lab’s scope of standard operations is summarized by the following categories andsize limits.
For a listing of A2LA-accredited measurements, see SCOPE OF
ACCREDITATION TO ISO/IEC 17025-2017 for the GLEASON METROLOGY SYSTEMSCALIBRATION LABORATORY, Certificate Number: 2054.01, available on-line atwww.gleason.com or upon request from Gleason Metrology Systems.
Standard Categories
Test pieces are organized according to the following general categories.
Artifacts:
Gleason Metrology Systems combination (helix & involute) master
Fellows lead master
Fellows involute master (new style; 1, 4.5, & 14 inch base circle)
Other helix and involute masters, within the size limits
Pitch artifacts, within the limits
Master Gears:
External or internal involute gears, helical or spur
Go/No-Go Gages (Plugs and Rings):
External or internal involute splines (full or sector), helical or spur

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Tapered Master Plugs:
External involute splines (full and sector), helical or spur
Standard Size Limits
Test pieces meeting the following criteria will be considered standard:
Maximum test diameter, externals or internals
Maximum external diameter, SIP measurements
Minimum internal diameter, SIP measurements
Maximum internal diameter, SIP measurements
Minimum base diameter, involute testing
Minimum test diameter, helix & pitch testing
Maximum base diameter, involute artifacts
Maximum base diameter, all other
Minimum minor diameter, internals
Minimum bore size (mounting on center)Maximum bore size (mounting on center)Maximum length (between centers)
Maximum face width
Maximum weight
Module, finest
Module, coarsest (master gears & spline gages)
Maximum helix angle
Minimum involute roll angle
Maximum involute roll angle
Maximum tolerance (potential deviation)
Maximum tolerance for involute & helix artifacts
Minimum diameter, spherical probe tip

300 mm (11.8 inches)
125 mm (4.9 inches)
20 mm (0.8 inches)
125 mm (4.9 inches)
5 mm (0.2 inches)
5 mm (0.2 inches)
356 mm (14.0 inches)
225 mm (8.9 inches)
20 mm (0.8 inches)
7 mm (0.3 inches)
125 mm (4.9 inches)
400 mm (15.7 inches)
100 mm (3.9 inches)
10 kg (22 lbs.)
1.0 module (24 DP)
5.0 module (5 DP)42
3 (less for larger base diameters)
42
35 m (0.0014 inches)
5 m (0.0002 inches)
0.5 mm (0.020 inches)

Test pieces beyond these limits may be considered for calibration provided that a) they
do not exceed limits stated in the Lab Scope of Accreditation document and b) the work
under consideration is reviewed and found to be suitable by the Lab Technical Manager.
In such cases, custom measurement uncertainty budgets may be constructed to moreaccurately reflect the given measurement process.

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Lab Measurement Services
The Lab provides five measurement services:
1) Non-Accredited Inspection Service
Description:

Usually applicable when test pieces are beyond the Lab's A2LA accredited scope of measurements or when traceability of results is not required. Test results are reported without statement of traceability or associated A2LA-accredited measurement uncertainty. Results may becompared to tolerance values provided by Customer and differences
highlighted. Determination of compliance is not stated or inferred.
GMS quotations for non-accredited inspection work must inform the Customer that such measurements are not carried out in accordance with
A2LA requirements.

Required Data Specified nominal geometry including, at a minimum:
normal pitch (module / diametral pitch)normal pressure angle
helix angle
Data must be on hand before testing procedures commence. In the absence of required data, the Lab may recommend its Reverse Engineering Service to establish nominal values for testing.
It is strongly recommended that the following data also be provided.
When this information is not provided, the Lab will use default values andprocedures unless directed otherwise by the Lab Technical Manager.
measurement system, inch / metric (Lab default is metric)
reference axis definition, if other than mounting centers
number of teeth
face width
major and minor diameters
tooth thickness or dimension over/under pins with specified pin size,
when appropriate
start of helix analysis (distance from end faces)
start of involute analysis (diameter, roll angle, or roll length) or
start of involute analysis, a.k.a. form diameter, TIF, SAP (diameter,roll angle, or roll length)
end of involute analysis (diameter, roll angle, or roll length)
Measurement
Uncertainty

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Not stated

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Traceability

Not reported

Reports Provided Inspection output sheets
2) Accredited Inspection Service
Description:

Applicable only when test pieces are within the Lab's A2LA accredited
scope of measurements. Intended for production test pieces that will not
be used to carry forward the chain of traceability. Test results are reported along with statements of traceability and associated A2LAaccredited measurement uncertainties, where appropriate. Results may
be compared to tolerance values provided by Customer and differences
highlighted. Determination of compliance is not stated or inferred.

Required Data Specified nominal geometry including, at a minimum:
normal pitch (module / diametral pitch)normal pressure angle
helix angle
Data must be on hand before testing procedures commence. In the absence of required data, the Lab may recommend its Reverse Engineering Service to establish nominal values for Measurement Service testing.
It is strongly recommended that the following data also be provided.
When this information is not provided, the Lab will use default values andprocedures unless directed otherwise by the Lab Technical Manager.
measurement system, inch / metric (Lab default is metric)
reference axis definition, if other than mounting centers
number of teeth
face width
major and minor diameters
tooth thickness or dimension over/under pins with specified pin size,
when appropriate
start of helix analysis (distance from end faces)
start of involute analysis (diameter, roll angle, or roll length) or
start of involute analysis, a.k.a. form diameter, TIF, SAP (diameter,roll angle, or roll length)
end of involute analysis (diameter, roll angle, or roll length)
Measurement
Uncertainty

Stated for each A2LA-accredited parameter measured

Traceability

Evidence provided by listing calibrated standards and equipment used

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Reports Provided Inspection Report provides measurement results and description oftest procedures and conditions, including at a minimum:
instrument modelsoftware version
ambient temperature limits
reporting temperature, after correction where applicable
test piece mounting conditions and orientation
specified nominal geometry values
reference axis definition, if other than mounting centerstest locations, if other than default (mid face width, pitch diameter)
direction of measurement (tolerancing) for each parameter observed
tooth / space testing method used (if appropriate)flank naming convention, including specified reference faceconventions for use of algebraic signs in helix or involute slope test
results
NIST traceable reference information
data filtering applied (where appropriate)
test datemeasurement technician
Lab test number
general condition of the test piece3) Reverse Engineering Service
Description:

Development of representative nominal geometry values on involute geometry cylindrical parallel axis gears and splines including pitch (module
or diametral pitch) pressure angle and helix angle from observations ofsample test piece(s). Reverse engineering observations of tooth flankgeometry are generally limited to base diameter and lead derived from
regression analysis of selected test trace regions. This analysis is affected by manufacturing deviations of the example test piece(s), modifications of the involute or helix geometry, and the actual extent of theselected analysis region. There are an infinite number of combinationsof gear parameters that will produce the same base diameter or lead.
Those produced by the reverse engineering process are representativeof the gear(s) observed, within the stated limitations, but are not unique.

Required Data None. When available, mounting center distance and number of teeth in
the mating gear can help refine the resulting values.
Test Procedure Find a set of nominal geometry values using the Gleason Metrology Systems GAMA option "Unknown Gear" or, when required, special calculations at the direction of the Lab Technical Manager.

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Documentation Listing of nominal values
4) Accredited Calibration Service
Description:

Applicable only when test pieces are within the Lab's A2LA accredited
scope of measurements. Intended for master test pieces that will be
used to carry forward the chain of traceability. Test results are reported
along with statements of traceability and associated A2LA-accredited
measurement uncertainties. Results may be compared to tolerance values provided by Customer and differences highlighted. Determination ofcompliance is not stated or inferred.

Required Data Specified nominal geometry including, at a minimum:
normal pitch (module / diametral pitch)normal pressure angle
helix angle
Data must be on hand before testing procedures commence. In the absence of required data, the Lab may recommend its Reverse Engineering Service to establish nominal values for Measurement Service testing.
It is strongly recommended that the following data also be provided.
When this information is not provided, the Lab will use default values andprocedures unless directed otherwise by the Lab Technical Manager.
measurement system, inch / metric (Lab default is metric)
reference axis definition, if other than mounting centers
number of teeth
face width
major and minor diameters
tooth thickness or dimension over/under pins with specified pin size,
when appropriate
start of helix analysis (distance from end faces)
start of involute analysis (diameter, roll angle, or roll length) or
start of involute analysis, a.k.a. form diameter, TIF, SAP (diameter,roll angle, or roll length)
end of involute analysis (diameter, roll angle, or roll length)
Measurement
Uncertainty

Stated for each A2LA accredited parameter calibrated

Traceability

Evidence provided by listing calibrated standards and equipment used

Reports Provided Calibration Report provides measurement results and description oftest procedures and conditions, including at a minimum:

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Standard Practices Calibration Laboratory
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v004, Feb 11, 2021

instrument modelsoftware version
ambient temperature limits
reporting temperature, after correction where applicable
test piece mounting conditions and orientation
specified nominal geometry values
reference axis definition, if other than mounting centerstest locations, if other than default (mid face width, pitch diameter)
direction of measurement (tolerancing) for each parameter observed
tooth / space testing method used (if appropriate)flank naming convention, including specified reference faceconventions for use of algebraic signs in helix or involute slope test
results
NIST traceable reference information
data filtering applied (if appropriate)
test datemeasurement technician
Lab test number
general condition of the test piece5) Compliance Service
Description:

Test results will be derived according to Customer-specified measurement and analysis methods then compared with Customer-specified tolerances to establish compliance to specifications. Test results may bereported along with statements of traceability and associated A2LAaccredited measurement uncertainties, where appropriate. Compliance
Service is only available for parameters for which the Lab has
A2LA-accredited measurement uncertainties.
When determining Compliance in the absence of specific Customer
instruction to the contrary, documented in their purchase order andacknowledged by Gleason Metrology Systems, the Lab will follow"guard banding" practice as recommended by ISO/TS 14253-1:1998,
Geometrical Product Specifications (GPS) - Inspection by measurementof work pieces and measuring equipment - Part 1: Decision rules forproving conformance or nonconformance with specifications. Accordingly, the tolerances will be reduced by the U95 measurement uncertainty
for the given measurement parameter before comparison with test values to determine compliance with specifications.
Whenever the Customer-specified analysis requires application ofa band-fitting method, the measurement result is inherently limited
to an observation of either an "in band" or "out of band" condition.

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Standard Practices Calibration Laboratory
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In all such cases, an accept/reject decision is inferred and Compliance Service methods shall be applied. In the absence of specificCustomer instruction to the contrary, documented in their purchaseorder and acknowledged by Gleason Metrology Systems, this is implemented by uniform reduction of the width of the specified bandby the U95 measurement uncertainty for the given measurement parameter. Compliance Service with the standard guard banding method
cannot be properly implemented when tolerance band design includes
regions where the width of the band is less than or equal to the U95 measurement uncertainty. It may not be possible to properly implement Compliance Service with standard guard banding when tolerances are provided in the form of non-uniform band-fit specifications due to incompatibility with the available validated software.
In all cases, measurement uncertainty is taken into consideration whencarrying out Compliance Service.
Required Data Specified nominal geometry including, at a minimum
measurement system, inch / metric (Lab default is metric)
reference axis definition, if other than mounting centers
number of teeth
normal pitch (module / diametral pitch)normal pressure angle
helix angle
face width
major and minor diameters
tooth thickness or dimension over/under pins with specified pin size,
when appropriate
start of helix analysis (distance from end faces)
start of involute analysis (diameter, roll angle, or roll length) or
start of involute analysis, a.k.a. form diameter, TIF, SAP (diameter,roll angle, or roll length)
end of involute analysis (diameter, roll angle, or roll length)
direction of measurement (tolerancing) for each parameter observed
an unambiguous specification of the analysis for each parameter
observed must be provided,(may be provided, when appropriate, by reference to established national standard),
other data as may be available per application
Data must be on hand before testing procedures commence.
Measurement
Uncertainty

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Stated for each A2LA-accredited parameter observed

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Standard Practices Calibration Laboratory
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v004, Feb 11, 2021

Traceability

Evidence provided by listing calibrated standards and equipment used

Reports Provided Compliance Report provides a statement of test piece compliance tospecifications, as provided by Customer, and description of test procedures and conditions, including at a minimum:
instrument modelsoftware version
ambient temperature limits
reporting temperature, after correction where applicable
test piece mounting conditions and orientation
specified nominal geometry values
reference axis definition, if other than mounting centerstest locations, if other than default (mid face width, pitch diameter)
direction of measurement (tolerancing) for each parameter observed
tooth / space testing method used (if appropriate)flank naming convention, including specified reference faceconventions for use of algebraic signs in helix or involute slope test
results
NIST traceable reference information
data filtering applied (if appropriate)
test datemeasurement technician
Lab test number
general condition of the test piece
Measurement results may also be reported.
Fitness for Use
The Gleason Metrology Systems Calibration Lab does not provide opinions concerning fitness for use of any test pieces.
Test Procedures, all Services except Reverse Engineering and Non-Accredited Inspection Service
In the absence of specific Customer instruction to the contrary, documented in their purchase order and acknowledged by Gleason Metrology Systems, and within the Lab's
scope of standard work for the given test piece, the following standard measurement practices will be carried out as appropriate:
Involute profile and helix
Measurements are made on the Lab's Gleason Metrology Systems 300GMSL instrument.
Test pieces are measured on both flanks of four teeth approximately 90 apart. For sector
Plugs and Rings, measurements are made on available teeth, excluding the outside flanks

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of last teeth in the sector. For center-relieved gears, both sections are measured for involute profile and helix deviations. Each feature of involute and helix reference artifacts
is tested at multiple mounting locations on the instrument and averaged. Analysis methods are described in detail under "Elemental Test Result Analysis Methods" below. Involute profile and helix slope deviation measurements of reference artifacts are adjusted fortest piece temperature following methods described in ISO/TR 10064-5. Measurement
methods follow AGMA 915-1-A02.
Pitch, et al
Measurements are made on the Lab's Gleason Metrology Systems 300GMSL instrument.
Test pieces are measured on both flanks of all teeth. Sectors are not tested for pitch
parameters. For center-relieved gears, both sections are measured for pitch deviations.
Pitch reference artifacts are tested at multiple mounting locations on the instrument andthe average value reported. Analysis methods are described in detail under "Elemental
Test Result Analysis Methods". Measurement methods follow AGMA 915-1-A02.
Tooth Thickness
Measurement of tooth thickness are made on the 300GMSL. The reported tooth
thickness shall be the average of all the gear teeth; derived from the angle measured
between the two tooth flanks of the starting tooth and the index deviations of all the teeth.
Dimension over/between pins (DOP)
The guide method “Dia-DOP_method-guide” shall be used to determine which instrument(Mahr ULM-600E or 300GMSL) to measure the DOP.
Measurements on external test pieces are made on the Lab's Mahr ULM-600E instrument
using calibrated gage pins, and when required by the three-pin method, a calibrated spanning gage block. DOP measurements on internal test pieces are made using calibrated
gage balls. DOP is measured in two places, approximately 90 apart and averaged. The
Lab will only measure DOP of external helical test pieces with odd numbers of teeth by
the three-pin method on the Mahr ULM-600E. In some cases, it may not be possible toimplement the three-pin method, owing to significant helix modification or limitations ofaxial pitch and face width. In these cases, the 300GMSL shall be used to measure DOP.
Sectors are tested at one location, where possible. DOP measurements may be adjusted
for test piece temperature, material compression, and actual (calibrated) pin sizes. Measurement methods follow ANSI/AGMA 2002-B88 (R1996).
When it is found that a part will not fit on the Mahr ULM-600E, the 300 GMSL instrument
shall be used to report the DOP measurements as computed from the physical measurement of the tooth thickness, both of which are accredited calibration values (tooth thickness and DOP on the 300GMSL).

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Tip diameter (outside or inside)
The guide method “Dia-DOP_method-guide” shall be used to determine which instrument(Mahr ULM-600E or 300GMSL) to measure the tip diameter.
Measurements on external test pieces with an even number of teeth are made on the
Lab's Mahr ULM-600E instrument, and when required, using calibrated gage pins. If thepart is found to not fit on the ULM-600E, or it has an odd number of teeth, then the
300GMSL may be used to calibrate the Tip diameter. Tip diameter measurements on
internal test pieces with an even number of teeth are made using calibrated gage balls.
When using the Mahr ULM-600E for Tip diameter measurements:
Tip diameter is measured in two places, approximately 90 apart and averaged. Measurements of external test pieces with odd numbers of teeth will only be made using theone-pin method. Associated calculations require DOP measurements by the two-pin
method. Measurements of internal test pieces with odd numbers of teeth can only bemade using the one-pin method. Associated calculations require DOP measurements by
the two-pin method. Sectors are tested at one location, where possible. Tip diametermeasurements may be adjusted for test piece temperature, material compression, andactual (calibrated) pin sizes.
Use of the 300GMSL has no restrictions on odd or even number of teeth on spur or helicalgears and splines.
Bore diameter
Measurements of external master gear bores are made on the Lab's Mahr ULM-600E
instrument. Bore diameter is measured in two places, approximately 90 apart and averaged. Bore diameter measurements may be adjusted for test piece temperature and material compression.
Measurement Uncertainty
All measurement processes exhibit both systematic and non-systematic deviations of reported results. In order to characterize the deviations of their report results, the Lab has
carried out extensive studies of their measurement processes, leading to statistical estimations of their U95 measurement uncertainties. These estimations have been made following the methods outlined in various standards, technical reports, information sheets,
and other documents published by ISO, AGMA, NIST, and others. Measurement results
reported with U95 measurement uncertainty values can be expected to be valid within thestated limits 95% of the time.
When carrying out the Compliance Service, the Lab is required by ISO/IEC 17025-2017
to take the associated measurement uncertainty into consideration. Accordingly, in the
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absence of specific Customer instruction to the contrary, documented in their purchaseorder and acknowledged by Gleason Metrology Systems, the tolerances will be reducedby the U95 measurement uncertainty for the given measurement parameter before comparison with test values to determine compliance with specifications.
Traceability
Traceability of elemental gear geometry measurements, i.e. involute, helix, and tooth location (pitch, et al) to the S.I. through NIST is established by use of reference gear-geometry artifacts calibrated at NIST (helix and profile), or by the Oak Ridge Metrology Center(ORMC) located at the Department of Energy’s Y-12 National Security Complex and operated by Consolidated Nuclear Security, LLC (CNS), under contract to the U.S. Department of Energy, or NIST. The ORMC establishes its gear metrology uncertainties in partnership with NIST in Gaithersburg, MD. NIST refers inquiries concerning calibration services for gear geometry artifacts to ORMC, stating in the process that measurement uncertainties for such calibrations will be identical for ORMC and NIST. ORMC is accreditedby the National Voluntary Laboratory Accreditation Program (NVLAP), an ILAC accredited
body, for the specific scope of accreditation under Lab Code 105000-0.
Traceability of other Lab measurements to the S.I. through NIST is established by use of
instruments, gage pins, gage blocks, master rings & plugs, gauging systems, and assorted
arbors and fixtures having current calibration documents from laboratories accredited by
A2LA or by an A2LA recognized accrediting organization. In some cases, these calibrations may be carried out by the Lab, under A2LA accredited calibration procedures.
A2LA Accreditation
The Gleason Metrology Systems Calibration Lab is accredited by the American Association for Laboratory Accreditation (A2LA), an ILAC accredited organization, under Certificate Number 2054.01. This indicates that Lab operations, including U 95 measurement
uncertainty estimation methods and the resulting uncertainty values, have been assessed
and found to comply with the requirements of ISO/IEC 17025:2017 (E) and A2LA-specified
requirements for Calibration Laboratories.
Lab measurement uncertainties accredited by A2LA are applicable within the scope ofstandard work limits listed in SCOPE OF ACCREDITATION TO ISO/IEC 17025-2017 for
the GLEASON METROLOGY SYSTEMS CALIBRATION LABORATORY, Certificate
Number: 2054.01 and summarized in this document under "SCOPE OF WORK". Revised
measurement uncertainty estimations may be made for applications that are beyond thesescope limitations. A2LA accreditation may apply to these estimations as well, dependingon the given circumstances. The Lab may also carry out measurements beyond the scopeof A2LA accreditation. Reported results of such measurements will be identified as suchin the Measurement Report.
Environmental Conditions

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The Lab is a temperature-controlled environment. Operations are prohibited if the ambient
temperature exceeds  1.8 F ( 1.0 C) from standard temperature of 68 F (20 C). Test
pieces are soaked in the Cal Lab environment for a minimum of 12 hours before measurement. When measuring involute or helix reference artifacts, observations of test piecetemperatures are made and results are mathematically compensated for observed temperature deviations from 20 C (68 F) following methods outlined in ISO/TR 10064-5.
Test piece measurements are prohibited if their temperature exceeds  1.5 C ( 2.7 F)
from standard temperature of 20 C (68 F).
The Lab works diligently to maintain a high level of cleanliness to minimize the effects ofparticulate contamination on measurement results.
Elemental Test Result Analysis Methods
In the absence of agreements to the contrary, documented in the purchase order andacknowledged by Gleason Metrology Systems, the Lab provides a default analysis of test
results based upon established practices of the Lab and the American gear industry.
Other optional analysis methods may be agreed to. This may involve use of alternative
analysis methods described in gear accuracy standards such as AGMA or ISO, whichusually require additional Customer-supplied information for proper implementation. Custom analysis according to Customer-defined methods may also be available. Custom
analysis requires availability of appropriate analysis software and additional Customersupplied information. Compliance Service requires Customer-specified analysis methods
and other information.
Reference Axis and Mounting
Measurement of gear involute, helix, and pitch parameters are made relative to a reference axis, which is defined by specification of datum features. The actual mounting configuration is at the discretion of the Lab Technical Manager or Lab Metrologist.
The reference axis of a test piece may be defined by integral centers. Often this is thecase with reference artifacts. Such test pieces are mounted and tested between instrument centers.
A bore may be specified as the datum feature that defines the reference axis. Such test
pieces may be mounted upon a test arbor, which is subsequently mounted between instrument centers.
Test pieces may alternatively be mounted in the free state upon the instrument table thencentered and tilted to optimize conformance to the specified test piece datum featureswith the reference axis of the instrument.
In some cases, standard Gleason Metrology Systems software modules may be used tomathematically adjust test results according to specified datum features, which are notprecisely mounted in conformance with the reference axis of the instrument.

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Reference Face
When possible, a reference face is selected. Unless otherwise noted in the calibration
report documents, the reference face for an external gear with an integral shaft and centers is the face adjacent the longer shaft feature. Unless otherwise noted in the calibration
report documents, the reference face for an external gear with a bore or for an internalgear is the face with the preponderance of imprinted information. Implementation of reference face selection is at the discretion of the Lab Technical Manager or Lab Metrologist.
Flank Naming Convention (USA)When viewing the reference face of the test piece, with the tip of a selected tooth above
its root, the tooth flank to the left will be the right flank and the tooth flank to the right willbe the left flank.
Tooth Numbering Convention
Teeth are numbered in a counterclockwise direction when viewing the reference face ofthe test piece.
Location of Tests
Involute and pitch testing are carried out at mid face width and helix and pitch testing iscarried out at the pitch diameter. For center-relieved gears, involute and pitch testing iscarried out at mid face width of each section.
Direction of Measurement
Involute, helix, and pitch tests are carried out with the measurement probe oriented todeflect tangent to the base diameter, within the transverse plane.
Direction of Deviation Reporting
Involute test values are reported tangent to the base diameter, within the transverse plane.
Helix test values are reported tangent to the base diameter, within the transverse plane.
Pitch test values are reported tangent to the measurement diameter, within the transverse
plane.
Helix and Involute Trace Data Filtering
Involute and helix test traces are filtered by the standard Gleason Metrology Systems
program option Medium Response, which produces moderate smoothing of trace data.
Helix and Involute Trace Data Density
Involute and helix test traces consist of an approximate target of 5 samples per mm along
the face width for helix or the base tangent (roll length) for involute with a minimum of 200
samples as a goal. The actual samples may vary depending on the actual measured
length for very small components.

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Master Gears, Plugs and Rings: Involute and Helix Analysis, Total Deviation
Measurements of involute and helix are made according to classic generative methods.
The Lab’s standard analysis of involute and helix measurements is carried out using
Gleason Metrology Systems GAMA DIN 3960/62 analysis software with LS best fit line
type selected. This method is based upon comparison of actual measurement traces toan unmodified involute of the specified base circle or to an unmodified helix with the specified lead. The parameter reported for these test pieces is Total Deviation. A straight linewith zero slope (angle) deviation, which is analogous to the specified (unmodified) involuteor helix, serves as the reference for observation of Total Deviation.
The Total Profile deviation value, Ff, is the distance between two non-sloping reference
straight lines, which enclose the actual involute test trace, within the analysis region.
The Total Helix deviation value, F, is the distance between two non-sloping reference
straight lines, which enclose the actual helix test trace, within the analysis region.
These methods represent standard practices commonly found within numerous national,
international, and company-proprietary gear and spline accuracy standards.
Reference Artifacts: Involute and Helix Analysis, Slope Deviation
Measurements of involute and helix are made according to classic generative methods.
The Gleason Metrology Systems Lab also uses GAMA DIN 3960/62 analysis softwarewith LS best fit line type selected when measuring involute and helix reference artifacts.
However, the reported parameter is Slope (Angle) Deviation, by best-fit line method. A
best-fit straight line (linear regression within the analysis region) serves as a reference forobservation of Slope Deviation.
The Involute Slope Deviation, fH, is the slope or rise of the best-fit line, within the specified
analysis region. This Slope Deviation value has positive polarity when the regression line
shows an increase in material toward the tooth tip, and visa versa. Positive Slope Deviation polarity is analogous with a negative deviation of the pressure angle and a positive
deviation of the base diameter.
The Helix Slope Deviation, fH, is the slope or rise of the best-fit line, within the specified
analysis region. This Slope Deviation value has positive polarity when the regression line
shows an increase in material toward the end of the given helix trace, and visa versa. The
relationship between associated helix angle deviation and lead deviation values is therefore dependent upon the flank and the hand of the helix being measured.
These methods represent standard practices commonly found within numerous national,
international, and company-proprietary gear and spline accuracy standards.
Center-Relieved Master Gears: Involute and Helix Analysis, Form and Slope Deviation

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The Gleason Metrology Systems Lab also uses GAMA General analysis software whenmeasuring center-relieved master gears. However, the reported parameters are Form
Deviation (for each section) and Slope (Angle) Deviation (overall), by construction line
method. A line constructed between points on each test trace at the limits of the overall
helix analysis region serves as a reference for observation of Slope (Angle) Deviation, byconstruction line method. The total combined effect of deviations within both sections ofeach center-relieved tooth flank is not observed.
The Total Profile deviation value, Ff, is the distance between two non-sloping reference
straight lines, which enclose the actual involute test trace, within the analysis region.
The Helix Form deviation value, ff, is the distance between two sloping reference straightlines, which enclose the actual helix test trace, within each analysis region. Slope of thesereference lines is determined by the corresponding best-fit straight line. The Helix Slope
Deviation, fH, by construction line method, is the slope or rise of the construction line,
within the specified overall helix analysis region. This Slope Deviation value has positive
polarity when the regression line shows an increase in material toward the end of the given
helix trace, and visa versa. The relationship between associated helix angle deviation andlead deviation values is therefore dependent upon the flank and the hand of the helix being
measured.
These methods represent standard practices commonly found within numerous national,
international, and company-proprietary gear and spline accuracy standards.
Plus/Minus Lead and Taper Replica Setting Master Gears: Helix Analysis, Total
and Slope Deviation
The Gleason Metrology Systems Lab also uses GAMA DIN 3960/62 analysis softwarewith LS best fit line type software when measuring plus/minus lead and taper replica setting master gears that are often used with double-flank composite testers having gimbal
instrumentation. Helix parameters reported include Average Helix (Lead) Slope Deviation(for plus/minus lead masters) and Summed Average Helix (Lead) Slope Deviations (fortaper masters). Some users prefer to enter these values when setting their composite
testers, rather than the specified design deviations of the master gears. Total Deviationis also reported for plus/minus lead masters and for taper masters.
Helix Analysis Region
The default analysis of helix test traces sets the analysis region to the central 80% of thespecified face width. For center-relieved gears, default analysis sets the Form Helix Deviation analysis region to the central 80% of the specified face width of each section and
the Slope (Angle) Deviation to the central 80% of the specified overall face width.
Involute Analysis Region

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Standard Practices Calibration Laboratory
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Involute analysis requires specification of an involute profile analysis region, including
Start of Involute Analysis and End of Involute Analysis locations. Additionally, a Start ofInvolute Test location, somewhat lower on the profile than the Start of Involute Analysis,should be specified. Gleason Metrology Systems standard analysis determines theselocations as follows:
1) Customer specified values for Start of Involute Analysis, End of Involute Analysis,and Start of Involute Test locations are applied when provided. Customer specified locations are adjusted when found to be below the base diameter or inaccessible with available probe tips.
2) When the Customer specifies a Form Diameter, Start of Active Profile (SAP), or
equivalent value, it is used as the Start of Analysis location. Unless specified to the contrary, the default End of Analysis location is calculated at 95% of the roll distance from theStart of Analysis to the specified OD. The Start of Involute Test location is calculated at
5% (below the Start of Analysis location) of the roll distance from the Start of Analysis tothe specified OD. Start of Involute Test and Start of Analysis locations are additionallyevaluated to avoid diameters smaller than the base diameter and for possible interferenceof the measurement probe tip with the root diameter and adjusted if necessary.
3) In the absence of a specified Form Diameter, Start of Active Profile (SAP), or equivalent value, a calculation is made to determine if the subject gear is undercut. If it is notundercut, a Lowest Point of Contact is calculated for the subject gear, presuming a rackmate, this rack having been shifted according to a comparison of the specified OD of thegear to the standard proportion OD. This Lowest Point of Contact is used as the Start ofAnalysis location. The End of Analysis location is calculated at 95% of the roll distancefrom the Start of Analysis to the specified OD. The Start of Involute Test location is calculated at 5% (below the Start of Analysis location) of the roll distance from the Start ofAnalysis to the specified OD. Start of Involute Test and Start of Analysis locations are
additionally evaluated to avoid diameters smaller than the base diameter and for possible
interference of the measurement probe tip with the root diameter and adjusted if necessary.
4) If the calculation shows that the subject gear is undercut, the Start of Analysis location is set at 10% of the roll length from the base diameter to the specified OD. The Endof Analysis location is calculated at 95% of the roll distance from the Start of Analysis tothe specified OD. The Start of Involute Test location is calculated at 5% (below the Start
of Analysis location) of the roll distance from the Start of Analysis to the specified OD.
Start of Involute Test and Start of Analysis locations are additionally evaluated to avoid
diameters smaller than the base diameter and for possible interference of the measurement probe tip with the root diameter and adjusted if necessary.
5) When testing involute splines, locations for Start of Involute Analysis and End of Involute Analysis are calculated according to ANSI/SAE B92.2M-1980, Metric Module

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Standard Practices Calibration Laboratory
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v004, Feb 11, 2021

Involute Splines and ANSI/SAE B92.1-1996, Involute Splines and Inspection. These calculated locations are adjusted when found to be inaccessible with available probe tips.
6) Involute profile analysis regions of reference artifacts are set per case, based upon
the design, existing calibration documents, and intended usage of the artifact.
In cases where base circle diameter, undercut, or root interference considerations require
adjustment of Start of Involute Test or Start of Analysis values, the End of Analysis value
may also be adjusted accordingly at the discretion of the Lab Technical Manager or Lab
Metrologist.
Pitch Analysis, et al
All measurements of pitch (tooth location) are made according to the classic single-probe
index method. The Lab’s standard analysis of pitch is carried out using Gleason Metrology
Systems GAMA DIN 3960/62 analysis software. This involves comparison of actual locations of individual tooth flanks relative to ideal equally spaced locations, at the reference
angle of 360 / z. Three tooth location parameters are included in this default method,
Total Cumulative Pitch, Single Pitch, and Runout.
The Total Cumulative Pitch parameter is the maximum algebraic difference between theposition deviation values of any two tooth flanks of the test piece, relative to their ideal
positions determined by summation of the appropriate number of reference angles.
The Single Pitch parameter is the maximum deviation of any adjacent pair of tooth flanks
from their ideal relative positions as determined by the reference angle.
The Runout parameter is the maximum algebraic difference between the radial positionsof a sphere placed into every tooth space. In practice, this observation is not physicallycarried out on the test piece. Standard Gleason Metrology Systems algorithms in the DIN
analysis software calculate Runout values from single-probe index measurements.
These methods represent standard practices commonly found within numerous national,
international, and company-proprietary gear and spline accuracy standards.

18/18

Gleason Metrology Systems Corporation
300 Progress Road
Dayton, OH 45449, USA

Tel +1 937 859-8273
www.gleason.com© Gleason Corporation
All rights reserved.