ISO TS 6336-20-2022 PDF

Full title and description

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 (second edition) specifies methods and formulae to evaluate the risk of scuffing (surface damage due to local overheating) for spur and helical gears using the flash-temperature (Blok) contact temperature concept.

Abstract

This document defines the flash-temperature method for calculating scuffing load capacity: it presents the governing formulae, required inputs (contact geometry, materials, lubrication and operating conditions), assumptions and applicability limits. The flash-temperature expressions are intended for band-shaped (or approximately band-shaped) Hertzian contact zones and working conditions characterized by sufficiently high Péclet numbers; the approach is based on Blok’s contact temperature concept.

General information

• Status: Published.
• Publication date: 24 May 2022.
• Publisher: ISO (International Organization for Standardization).
• ICS / categories: 21.200 (Gear drives / transmissions).
• Edition / version: Edition 2 (2022).
• Number of pages: 34.

Scope

Specifies procedures and formulae to assess scuffing (adhesive wear due to local transient temperature rises) for spur and helical gear teeth using the flash temperature method. It applies where the contact geometry produces a band-shaped Hertzian contact and where thermal-advection conditions (Péclet number) justify the flash-temperature assumptions. The document covers calculation steps, required input data (geometry, material thermal and mechanical properties, lubricant properties, operating speeds and loads), limitations of the method and guidance for interpretation of results.

Key topics and requirements

• Flash-temperature (Blok) formulation for transient contact temperature rise and its use in scuffing risk evaluation.
• Definition of applicable contact geometry (band-shaped Hertzian contacts) and Péclet-number requirement for validity.
• Required input parameters: gear geometry, contact pressure, sliding/rolling speed, material thermal/mechanical properties, lubricant thermal properties and film characteristics.
• Calculation workflow: determination of flash temperature, comparison with material/lubricant scuffing limits, and assessment of load capacity against scuffing.
• Assumptions, limitations and recommended care when applying the method beyond specified conditions.

Typical use and users

Used by mechanical design engineers, gear designers, tribologists, gearbox and automotive drivetrain developers, researchers studying gear surface damage, and standards/qualification engineers. Typical applications include design and validation of gear tooth surfaces, lubricant selection and sizing of safety margins to avoid scuffing under specified operating conditions.

Related standards

Part of the ISO 6336 series on calculation of load capacity of spur and helical gears (other parts cover geometry, bending strength, pitting, wear, corrections and different temperature methods). ISO/TS 6336-21 (Integral temperature method) is a closely related Technical Specification addressing an alternative scuffing evaluation method. National adoptions and related regional standards align with the ISO 6336 family.

Keywords

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

FAQ

Q: What is this standard?

A: ISO/TS 6336-20:2022 is a Technical Specification (Part 20 of the ISO 6336 series) that provides the flash-temperature method for calculating scuffing load capacity of spur and helical gears.

Q: What does it cover?

A: It covers the flash-temperature (Blok) formulation, required input data and a calculation workflow to evaluate scuffing risk and scuffing-related load capacity, including assumptions, applicability limits (band-shaped Hertzian contact, sufficiently high Péclet numbers) and interpretation guidance.

Q: Who typically uses it?

A: Gear designers, drivetrain and gearbox engineers, tribology specialists, researchers and standards engineers who need to assess or limit the risk of scuffing in gear contacts.

Q: Is it current or superseded?

A: The document is current as ISO/TS 6336-20:2022 (Edition 2), published 24 May 2022; it replaces the earlier 2017 version. For the latest status check the official ISO bibliographic entry or national standards bodies.

Q: Is it part of a series?

A: Yes — it is Part 20 of the ISO 6336 series (Calculation of load capacity of spur and helical gears). Closely related parts include other 6336 parts covering pitting, bending strength, wear and different temperature-based scuffing assessment methods (for example Part 21).

Q: What are the key keywords?

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