ISO 8740:1997

Overview

ISO 8740:1997 covers grooved pins - full-length parallel grooved, with chamfer. The standard specifies the geometry, materials, dimensional limits and installation practice for three-groove pins manufactured in mild steel or austenitic stainless steel, with nominal diameters from 1.5 mm to 25 mm. These pins are intended for press-fit applications where a tight fit, predictable shear performance and interchangeability are required.

Key Topics

• Geometry and features: Pins have three constant, evenly spaced grooves running the full length and a chamfered end. The chamfer angle (a) is specified between 15° and 30°. A groove angle of 70° is referenced for steel pins and may be adjusted depending on material resilience.

• Materials and hardness: Typical materials are mild (carbon) steel and austenitic stainless steel. Hardness guidance in the standard includes ranges such as ~125–245 HV30 for soft steel and ~210–280 HV30 for stainless A1 (see ISO 3506-1 for stainless fastener characteristics).

• Dimensional limits and hole fit: Nominal pin diameters run from 1.5 mm to 25 mm. The receiving hole diameter must equal the pin nominal diameter with a tolerance grade of H11 to achieve the specified press-fit behavior.

• Surface finish and protection: Normal delivery is in the as-manufactured state with a protective lubricant unless otherwise agreed. Preferred coatings include black oxide, phosphate conversion coatings and zinc with chromate conversion (see ISO 9717 and ISO 4042).

• Quality and testing: Pins must be free from harmful defects. Shear resistance testing is performed in accordance with ISO 8749 and acceptance/reception procedures follow ISO 3269.

Applications

ISO 8740 grooved pins are used where compact, reliable dowel or shear connections are required, for example:

• Securing components in assemblies subject to shear loads
• Locating or indexing parts where a tight press-fit is needed
• Applications requiring interchangeability between suppliers

Practical benefits include predictable press-fit behavior, controlled shear performance and straightforward designation for procurement and quality control.

Related Standards

• ISO 3269 - Fasteners: reception inspection
• ISO 3506-1 - Mechanical properties of corrosion-resistant stainless steel fasteners (reference to stainless A1 hardness guidance)
• ISO 4042 - Fasteners: electroplated coatings (referenced for coatings)
• ISO 8749 - Pins: shear test method
• ISO 9717 - Phosphate conversion coatings

Notes

• Typical designation examples from the standard: Goupille cannelée ISO 8740 - 6 · 50 - St (mild steel) or Goupille cannelée ISO 8740 - 6 · 50 - A1 (stainless A1).
• For materials or coatings outside those listed, customer and supplier agreement is required.

For engineers and procurement teams, ISO 8740:1997 provides the baseline for selecting, specifying and testing full-length parallel grooved pins with chamfer in mechanical assemblies.