ISO/TS 10300-20:2021

Calculation of load capacity of bevel gears — Part 20: Calculation of scuffing load capacity — Flash temperature method

This document provides a calculation method for bevel and hypoid gears regarding scuffing based on experimental and theoretical investigation[7]. This calculation method is a flash temperature method. The formulae in this document are intended to establish uniformly acceptable methods for calculating scuffing resistance of straight, helical (skew), spiral bevel, Zerol and hypoid gears made of steel. They are applicable equally to tapered depth and uniform depth teeth. Hereinafter, the term “bevel gear” refers to all of these gear types; if not the case, the specific forms are identified. A calculation method of the scuffing load capacity of bevel and hypoid gears based on an integral temperature method is not available when this document is published. The formulae in this document are based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of εvα

Calcul de la capacité de charge des engrenages coniques — Partie 20: Calcul de la capacité de charge au grippage — Méthode de la température-éclair

General Information

• Status: Published
• Publication Date: 06-Apr-2021
• ICS: 21.200 - Gears
• Technical Committee: ISO/TC 60/SC 2 - Gear capacity calculation
• Drafting Committee: ISO/TC 60/SC 2/WG 13 - Bevel gears
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 10-Sep-2024

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 10300-20
First edition
2021-04
Calculation of load capacity of bevel
gears —
Part 20:
Calculation of scuffing load capacity —
Flash temperature method
Calcul de la capacité de charge des engrenages coniques —
Partie 20: Calcul de la capacité de charge au grippage — Méthode de
la température-éclair
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Virtual cylindrical gear . 4
5.1 General . 4
5.2 Local geometry parameters . 5
5.2.1 Transverse path of contact . 5
5.2.2 Length of contact lines . 6
5.2.3 Local equivalent radius of curvature, ρ .
rel,Y 8
5.2.4 Local load sharing factor, X .
LS,Y 8
6 Stresses and velocities . 9
6.1 Local modified contact stress, σ .
H,mod,Y 9
6.2 Sliding and sum of velocities .10
6.3 Local relative lubricating film thickness, λ .
z,Y 11
6.4 Local coefficient of friction, µ .
Y 14
7 Local contact temperature, θ .14
C,Y
7.1 General .14
7.2 Power losses influencing the bulk temperature.15
7.2.1 General.15
7.2.2 Method A .15
7.2.3 Method B .15
7.2.4 Method C .15
7.3 Bulk temperature, θ .
M 15
7.3.1 General.15
7.3.2 Method A .15
7.3.3 Method B .15
7.3.4 Tip relief factor, X .
CA 17
7.4 Local flash temperature, θ .
fl,Y 17
8 Permissible contact temperature .18
8.1 Limit temperature from scuffing test, θ .
S,DIN 18
8.2 Permissible temperature, θ .
SC 19
8.3 Permissible scuffing temperature, θ .
S,Y 20
9 Local safety factor, S .21
S,Y
Bibliography .22
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.
A list of all parts in the ISO 10300 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

Introduction
The ISO 10300 series consists of International Standards, Technical Specifications (TS) and Technical
Reports (TR) under the general title Calculation of load capacity of bevel gears (see Table 1).
— International Standards contain calculation methods that are based on widely accepted practices
and have been validated.
— TS contain calculation methods that are still subject to further development.
— TR contain data that is informative, such as example calculations.
The procedures specified in ISO 10300 parts 1 to 19 cover fatigue analyses for gear rating. The
procedures described in ISO 10300 parts 20 to 29 are predominantly related to the tribological
behaviour of the lubricated flank surface contact. ISO 10300 parts 30 to 39 include example calculations.
The ISO 10300 series allows the addition of new parts under appropriate numbers to reflect knowledge
gained in the future.
Requesting standardized calculations according to the ISO 10300 series without referring to specific
parts requires the use of only those parts that are currently designated as International Standards (see
Table 1 for listing). When requesting further calculations, the relevant part or parts of the ISO 10300
series need to be specified. Use of a Technical Specification as acceptance criteria for a specific design
need to be agreed in advance between manufacturer and purchaser.
Table 1 — Parts of ISO 10300 series (status as of DATE OF PUBLICATION)
Calculation of load capacity of bevel gears International Technical Technical
Standard Specification Report
a
Part 1: Introduction and general influence factors X
a
Part 2: Calculation of surface durability (pitting) X
a
Part 3: Calculation of tooth root strength X
Part 4 to 19: to be assigned
Part 20: Calculation of scuffing load capacity — Flash X
temperature method
Part 21 to 29: to be assigned
Part 30: ISO rating system for bevel and hypoid gears  X
— Sample calculations
Part 32: ISO rating system for bevel and hypoid gears  X
— Sample Calculations of scuffing load capacity
a
Under revision.
This document and the other parts of the ISO 10300 series provide a coherent system of procedures
for the calculation of the load capacity of bevel and hypoid gears. The ISO 10300 series is designed to
facilitate the application of future knowledge and developments, and also the exchange of information
gained from experience.
Design considerations to prevent fractures emanating from stress raisers in the tooth flank, tip
chipping and failures of the gear blank through the web or hub will need to be analysed by general
machine design methods.
Several methods for the calculation of load capacity, as well as for the calculation of various factors, are
permitted. The directions in the ISO 10300 series are thus complex, but also flexible.
Scuffing is a localized damage caused by solid-phase welding between sliding surfaces. It is accompanied
by transfer of metal from one surface to another due to welding and tearing. Scuffing can occur in
gear flanks that operate in the boundary-lubrication regime where the lubricant film is insufficient
to separate tooth surfaces and contact breaks through the oxide layers that normally protect the
[4]
surfaces and enables bare metal surfaces to weld together. Blok hypothesized that scuffing occurs
when the maximum surface temperature in the contact reaches a critical value. The maximum contact
temperature is determined by the sum of the gear tooth bulk temperature and the local, instantaneous
flash temperature. Scuffing risk is determined by comparing the maximum contact temperature to the
critical temperature. The critical temperature is not only a function of the lubricant-metal-atmosphere
combination; but it depends also upon operating conditions and surface characteristics. Consequently,
the most reliable critical temperatures are determ
...

TECHNICAL ISO/TS
SPECIFICATION 10300-20
First edition
2021-04
Calculation of load capacity of bevel
gears —
Part 20:
Calculation of scuffing load capacity —
Flash temperature method
Calcul de la capacité de charge des engrenages coniques —
Partie 20: Calcul de la capacité de charge au grippage — Méthode de
la température-éclair
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Virtual cylindrical gear . 4
5.1 General . 4
5.2 Local geometry parameters . 5
5.2.1 Transverse path of contact . 5
5.2.2 Length of contact lines . 6
5.2.3 Local equivalent radius of curvature, ρ .
rel,Y 8
5.2.4 Local load sharing factor, X .
LS,Y 8
6 Stresses and velocities . 9
6.1 Local modified contact stress, σ .
H,mod,Y 9
6.2 Sliding and sum of velocities .10
6.3 Local relative lubricating film thickness, λ .
z,Y 11
6.4 Local coefficient of friction, µ .
Y 14
7 Local contact temperature, θ .14
C,Y
7.1 General .14
7.2 Power losses influencing the bulk temperature.15
7.2.1 General.15
7.2.2 Method A .15
7.2.3 Method B .15
7.2.4 Method C .15
7.3 Bulk temperature, θ .
M 15
7.3.1 General.15
7.3.2 Method A .15
7.3.3 Method B .15
7.3.4 Tip relief factor, X .
CA 17
7.4 Local flash temperature, θ .
fl,Y 17
8 Permissible contact temperature .18
8.1 Limit temperature from scuffing test, θ .
S,DIN 18
8.2 Permissible temperature, θ .
SC 19
8.3 Permissible scuffing temperature, θ .
S,Y 20
9 Local safety factor, S .21
S,Y
Bibliography .22
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.
A list of all parts in the ISO 10300 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

Introduction
The ISO 10300 series consists of International Standards, Technical Specifications (TS) and Technical
Reports (TR) under the general title Calculation of load capacity of bevel gears (see Table 1).
— International Standards contain calculation methods that are based on widely accepted practices
and have been validated.
— TS contain calculation methods that are still subject to further development.
— TR contain data that is informative, such as example calculations.
The procedures specified in ISO 10300 parts 1 to 19 cover fatigue analyses for gear rating. The
procedures described in ISO 10300 parts 20 to 29 are predominantly related to the tribological
behaviour of the lubricated flank surface contact. ISO 10300 parts 30 to 39 include example calculations.
The ISO 10300 series allows the addition of new parts under appropriate numbers to reflect knowledge
gained in the future.
Requesting standardized calculations according to the ISO 10300 series without referring to specific
parts requires the use of only those parts that are currently designated as International Standards (see
Table 1 for listing). When requesting further calculations, the relevant part or parts of the ISO 10300
series need to be specified. Use of a Technical Specification as acceptance criteria for a specific design
need to be agreed in advance between manufacturer and purchaser.
Table 1 — Parts of ISO 10300 series (status as of DATE OF PUBLICATION)
Calculation of load capacity of bevel gears International Technical Technical
Standard Specification Report
a
Part 1: Introduction and general influence factors X
a
Part 2: Calculation of surface durability (pitting) X
a
Part 3: Calculation of tooth root strength X
Part 4 to 19: to be assigned
Part 20: Calculation of scuffing load capacity — Flash X
temperature method
Part 21 to 29: to be assigned
Part 30: ISO rating system for bevel and hypoid gears  X
— Sample calculations
Part 32: ISO rating system for bevel and hypoid gears  X
— Sample Calculations of scuffing load capacity
a
Under revision.
This document and the other parts of the ISO 10300 series provide a coherent system of procedures
for the calculation of the load capacity of bevel and hypoid gears. The ISO 10300 series is designed to
facilitate the application of future knowledge and developments, and also the exchange of information
gained from experience.
Design considerations to prevent fractures emanating from stress raisers in the tooth flank, tip
chipping and failures of the gear blank through the web or hub will need to be analysed by general
machine design methods.
Several methods for the calculation of load capacity, as well as for the calculation of various factors, are
permitted. The directions in the ISO 10300 series are thus complex, but also flexible.
Scuffing is a localized damage caused by solid-phase welding between sliding surfaces. It is accompanied
by transfer of metal from one surface to another due to welding and tearing. Scuffing can occur in
gear flanks that operate in the boundary-lubrication regime where the lubricant film is insufficient
to separate tooth surfaces and contact breaks through the oxide layers that normally protect the
[4]
surfaces and enables bare metal surfaces to weld together. Blok hypothesized that scuffing occurs
when the maximum surface temperature in the contact reaches a critical value. The maximum contact
temperature is determined by the sum of the gear tooth bulk temperature and the local, instantaneous
flash temperature. Scuffing risk is determined by comparing the maximum contact temperature to the
critical temperature. The critical temperature is not only a function of the lubricant-metal-atmosphere
combination; but it depends also upon operating conditions and surface characteristics. Consequently,
the most reliable critical temperatures are determ
...