PD ISO TS 6336-20-2022 PDF

Full title and description

PD ISO/TS 6336-20:2022 — Calculation of load capacity of spur and helical gears — Part 20: Calculation of scuffing load capacity — Flash temperature method. This technical specification gives methods and formulae, based on Blok's contact temperature concept, for evaluating the risk of scuffing (local welding or severe adhesive wear) in gear contacts under dynamic conditions.

Abstract

This document specifies calculation methods (flash-temperature approach) for assessing scuffing risk in band-shaped or approximately band-shaped Hertzian contact zones for spur and helical gears, under conditions where the Péclet number is sufficiently high. The approach provides formulae to estimate flash (local) contact temperatures and to compare those temperatures and load conditions against material and lubricant limits to judge scuffing susceptibility.

General information

• Status: Published / Valid.
• Publication date: 24 May 2022 (Edition 2, 2022).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 21.200 — Gears.
• Edition / version: Edition 2 (2022), replaces ISO/TS 6336-20:2017.
• Number of pages: 34 pages (ISO published PDF length).

Scope

The technical specification provides methods and formulae to evaluate the risk of scuffing for spur and helical gear teeth using the flash-temperature (local contact temperature) concept introduced by Blok. It is intended for band-shaped (or approximately band-shaped) Hertzian contacts and for operating regimes where transient heat advection/diffusion (Péclet number) conditions make the flash-temperature model applicable. The methods are applicable to gear design and analysis to help predict scuffing limits given geometry, materials, surface finish, and lubrication conditions.

Key topics and requirements

• Flash temperature calculation methods for gear tooth contacts (Blok’s concept and associated formulae).
• Application limits: band-shaped Hertzian contacts and sufficiently high Péclet numbers.
• Inputs required: contact geometry, load distribution, sliding/rolling conditions, material thermal and mechanical properties, and lubricant characteristics.
• Evaluation criteria to compare calculated local temperatures/loads with material and lubricant scuffing thresholds.
• Guidance for using the flash-temperature results within gear load-capacity assessments (as part of ISO 6336 family practices).

Typical use and users

Engineers and designers of gearboxes and mechanical transmissions use this specification during design, failure analysis, and validation of gear systems where scuffing risk is a concern (e.g., high-speed or high-temperature applications, limited lubrication, or mixed elastohydrodynamic regimes). Typical users include mechanical design engineers, tribologists, test engineers, gearbox manufacturers, and standards bodies integrating gear-capacity checks into product requirements.

Related standards

This document is one part of the ISO 6336 series (calculation of load capacity of spur and helical gears). Closely related parts include ISO/TS 6336-21 (scuffing — integral temperature method), ISO/TS 6336-22 (micropitting), and the ISO/TR 6336-30/31 calculation examples and guidance documents; the series and individual parts are managed by ISO/TC 60/SC 2 (Gears).

Keywords

scuffing, flash temperature, Blok temperature, gear load capacity, spur gear, helical gear, Hertzian contact, Péclet number, lubrication, tribology, ISO 6336.

FAQ

Q: What is this standard?

A: ISO/TS 6336-20:2022 is a technical specification that defines the flash-temperature method for calculating scuffing load capacity of spur and helical gears, providing formulae and application limits to assess scuffing risk.

Q: What does it cover?

A: It covers calculation procedures based on Blok's contact-temperature concept for band-shaped Hertzian contacts, required inputs (geometry, materials, lubrication), applicability conditions (high enough Péclet numbers), and how to interpret calculated flash temperatures relative to scuffing limits.

Q: Who typically uses it?

A: Gear designers, gearbox manufacturers, tribology specialists, test and validation engineers, and standards committees concerned with gear load-capacity assessment and prevention of adhesive wear in gears.

Q: Is it current or superseded?

A: The 2022 edition (published 24 May 2022) is the current published edition and supersedes ISO/TS 6336-20:2017, which was withdrawn.

Q: Is it part of a series?

A: Yes — it is part of the ISO 6336 family on calculation of load capacity of spur and helical gears; related parts handle other failure modes and calculation methods (for example, integral-temperature scuffing methods, micropitting, and worked examples).

Q: What are the key keywords?

A: Scuffing, flash temperature, Blok temperature, gear tooth contact, Hertzian contact, Péclet number, spur gear, helical gear, lubrication, ISO 6336.