ISO 12925-2:2020

Overview

ISO 12925-2:2020 defines specifications and an extended classification for gear lubricants used in open and semi-enclosed gear systems. Aligned with ISO 6743-6, the standard covers mineral- and synthetic‑based products in categories CKH, CKJ and CKM, and introduces sub-categories for environmentally acceptable lubricants. It specifies minimum requirements, sampling guidance and extended viscosity grades for very viscous gear oils, while excluding extreme temperature or extreme‑load cases (which require bespoke agreements between supplier and purchaser).

Key topics and technical requirements

• Scope and classification: Expanded classification of open‑gear lubricants (CKH, CKJ, CKM) and CKJ sub‑categories (including products with solid lubricants denoted CKJ‑F, and other suffixes listed in the standard).
• Viscosity grading: Extension of ISO 3448 to include higher viscosity grades for open gears; viscosity is defined using kinematic viscosity at 40 °C and for very viscous products at 100 °C.
• Minimum property requirements: Criteria for corrosion protection, anti‑wear/extreme‑pressure performance and adhesion suited to low‑speed, high‑load open gears.
• Environmentally acceptable lubricants: Additional requirements and test methods for biodegradability, aquatic toxicity and bio‑based content (references include ISO biodegradability and ecotoxicity methods and standards such as ISO 9408, ISO 9439, ISO 6341 and EN 16807).
• Test methods and sampling: Normative references include ISO 3104 (viscosity), ISO 3170 (sampling), ISO 14635 (FZG scuffing tests) and flash/pour point and density test standards.
• Practical limits and notes: The standard covers commonly encountered industrial open and semi‑enclosed gear applications but excludes extreme temperature/charge scenarios - additional testing may be mutually agreed.

Applications and users

ISO 12925-2:2020 is used to:

• Specify and select open‑gear and semi‑enclosed gear oils for industries such as mining, steel, cement, heavy machinery and power generation.
• Guide lubricant manufacturers on formulation and labeling (including environmental sub‑categories).
• Support maintenance engineers, procurement teams and OEMs in drafting lubricant specifications and supplier contracts.
• Provide test laboratories with the normative references needed to verify conformity (viscosity, FZG scuffing, corrosion, biodegradability and ecotoxicity tests).

Related standards

• ISO 6743-6 (classification framework for lubricants)
• ISO 3448 (ISO VG viscosity classes)
• ISO 3170 (sampling)
• ISO 14635 (FZG scuffing tests)
• Relevant ISO water‑quality and biodegradability methods (ISO 9408, ISO 9439, ISO 6341) and EN 16807

Keywords: ISO 12925-2:2020, open gear lubricants, CKH CKJ CKM, environmentally acceptable lubricants, viscosity grades, ISO 6743-6, gear oils, FZG test, biodegradability.