Overview
ISO 10511:2025 - Fasteners - Prevailing torque hexagon nuts - Thin nuts (with non‑metallic insert) - is the third-edition ISO standard that defines the characteristics, dimensions and manufacturing/acceptance requirements for prevailing‑torque hexagon thin nuts with a non‑metallic insert. It covers steel and stainless‑steel thin nuts with metric coarse‑pitch threads M3 to M39, offered in product grades A and B. The standard clarifies design principles (style 0 thin nuts), includes dimensional tables for M5–M39 and a normative Annex A for nuts with D < M5, and adds marking and labelling requirements.
Key topics and technical requirements
- Scope and design: Specifies overall nut height equal to the base height (mmin per ISO 898‑2 / ISO 4035 for style 0) plus the prevailing‑torque feature. The insert height (hmax − mmin) is identical across regular, high and thin nuts for a given diameter.
- Dimensions: Detailed dimensions and tolerances for M5–M39 in main tables; nuts with D < M5 covered in Annex A (M3, M4). Symbols and dimension descriptions follow ISO 225.
- Materials and grades: Applies to steel and stainless steel; stainless‑steel grades and property classes may be selected from ISO 3506‑2 when required. Steel nuts follow applicable ISO 898‑2 provisions (QT or NQT as noted).
- Functional properties and testing: Functional requirements reference ISO 2320 for prevailing‑torque steel nuts. For stainless steel, no international prevailing‑torque test exists - purchasers and suppliers should agree test methods (national standards or technical specifications).
- Threading and tolerances: Thread tolerance class 6H (6G allowed for coatings); general thread tolerances per ISO 965‑1. Product grades and tolerances per ISO 4759‑1.
- Surface treatments and coatings: As processed (steel) or clean and bright (stainless), with optional coatings per ISO 4042 (electroplated) or ISO 10683 (zinc flake).
- Safety note: WARNING - Thin nuts (style 0) have reduced loadability and are not designed to provide resistance to thread stripping (see ISO 898‑2).
Applications and users
ISO 10511:2025 is primarily used by:
- Fastener manufacturers and tooling designers for dimensioning and production of prevailing‑torque thin hexagon nuts with non‑metallic inserts.
- Engineering designers and assembly engineers specifying locking nuts where limited height is required.
- Procurement, quality assurance and inspection teams enforcing acceptance, marking and labelling requirements.
- Suppliers and customers negotiating functional tests, coatings and stainless‑steel grades for corrosion or service‑specific needs.
Common applications include assemblies requiring vibration-resistant locking in confined spaces where thin nuts are preferred, provided reduced stripping resistance is acceptable.
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