ISO 8741:2025

Overview

ISO 8741:2025 specifies the characteristics of reverse‑taper grooved pins - half‑length progressive grooves (closed ends) manufactured in steel and stainless steel, with nominal diameters from 1 mm to 25 mm. These grooved pins are intended for positioning/guiding and for enabling relative rotation of assembled parts. The design provides easy installation (reverse‑taper shape) and a medium level of pull‑out resistance through elastic fit behaviour. General functional principles and common requirements for grooved pins and assembly are given in ISO 13669.

Key topics and requirements

• Geometry and dimensions: detailed dimensions and standard length ranges for nominal diameters 1–25 mm; groove length is specified as l/2 with defined tolerances depending on pin length.
• Groove location: grooves must remain closed at the ends; the start of grooves must be positioned within lmax limits that depend on overall length (e.g., l ≤ 10 mm → lmax = 1 mm; 10 < l ≤ 50 mm → lmax = 2 mm, etc.).
• Ends and options: pins are manufactured with rounded ends by default (RN); chamfered ends (CH) are available on request.
• Control parameters: expanded diameter (d) and pin straightness (t) are controlled as specified in ISO 13669; expanded diameter values differ for steel and stainless steel and are given across length ranges.
• Materials and finishes: standard materials are steel (St) and stainless steel grades (A1, A2, A4, C1, F1). Coatings and surface treatments follow referenced standards (e.g., ISO 4042, ISO 10683, ISO 9717); passivation guidance referenced (ISO 16048).
• Quality and inspection: acceptance inspection per ISO 3269; workmanship requires pins free of burrs and detrimental defects.
• Labelling and designation: package labelling must include ISO 8741 reference, nominal diameter and length, end option (CH), material symbol, surface condition, manufacturer ID, lot number and quantity.

Applications and users

ISO 8741 grooved pins are used where precise positioning, guiding or controlled rotational relationship of parts is required with straightforward installation and moderate pull‑out resistance. Typical users include:

• Fastener and component manufacturers (production and supply)
• Design and mechanical engineers specifying pins for assemblies
• Procurement and quality inspectors checking conformity to dimensional, material and labelling requirements
• OEMs in machinery, equipment manufacturing and precision assemblies that reference ISO fastener standards

Related standards

Key referenced and related documents:

• ISO 13669 - Grooved pins: general requirements (functional principles, control of d and straightness)
• ISO 13670, ISO 13672, ISO 8739–8747 family - other grooved‑pin types and profiles
• ISO 3506‑6, ISO 4042, ISO 10683, ISO 9717, ISO 3269, ISO 1891‑4

Keywords: ISO 8741:2025, reverse‑taper grooved pins, half‑length progressive grooves, fasteners, grooved pins, expanded diameter, pin straightness, dimensions, stainless steel.