ISO/TR 6336-31:2018 PDF

Overview

ISO/TR 6336-31:2018 is a Technical Report in the ISO 6336 series that provides worked calculation examples for determining the micropitting load capacity of spur and helical gears. It is informative guidance for applying the procedures given in ISO/TS 6336‑22 (Calculation of micropitting load capacity), illustrating the calculation workflow, input data, and result presentation. The document is explicit that the example values are guidance only and must not be used as material or lubricant allowables or as direct micro‑geometry recommendations for real applications.

Key topics and technical content

• Worked examples showing step‑by‑step application of the micropitting calculation procedure from ISO/TS 6336‑22.
• Examples cover a range of gear types and operating conditions, including spur gears, helical gears, and a speed increaser.
• Presentation of both Method A and Method B calculations (where applicable) to compare approaches for micropitting assessment.
• Input data and calculation outputs include parameters relevant to tribology and contact mechanics: surface roughness, contact/flash temperature, dynamic and local viscosities, local lubricant film thickness (λ_GF,Y), and calculation of the micropitting safety factor (Sλ).
• Guidance on determining permissible film thickness values (λ_GFP) is referenced to ISO/TS 6336‑22 rather than provided as prescriptive limits.
• Examples include full calculation details for initial steps and summarized results for later steps; where available, operational or laboratory wear photos/measurements are referenced to relate calculations to observed micropitting.

Practical applications - who should use it

• Gear designers and drivetrain engineers who need worked examples to implement micropitting assessments in gear design and review.
• Tribologists and lubrication engineers evaluating lubricant film thickness, pressure–viscosity behavior, and contact conditions for gear flank surfaces.
• Test laboratories and researchers using ISO/TS 6336‑22 who want validated worked examples to verify calculation tools and spreadsheets.
• Maintenance, reliability, and application engineers assessing micropitting risk for high‑speed or low‑speed gear sets in industry sectors such as wind, automotive, marine, and industrial gearboxes.

Related standards

• ISO/TS 6336‑22 (Calculation of micropitting load capacity) - primary technical specification for the calculations used.
• ISO 6336‑1 and ISO 6336‑2 - general gear load capacity and surface (pitting) calculation procedures.
• ISO 21771, ISO 1122‑1 and other normative references included in the TR.

Note: ISO/TR 6336‑31 is an informative supplement; for prescriptive design limits, follow the relevant normative parts (ISO/TS or ISO standards) and agree with purchaser/manufacturer on acceptance criteria.