ISO 8739:1997

Overview

ISO 8739:1997 specifies the international standard for grooved pins that feature full-length parallel grooves with a pilot end. These grooved pins are used as precision fastening elements primarily made from mild steel or austenitic stainless steel. The standard defines precise dimensional, mechanical, and material requirements to ensure consistent performance and reliable fit in assembly applications.

This second edition of ISO 8739, issued in November 1997, replaces the first edition from 1986 and incorporates technical revisions to better align with contemporary industrial needs. The standard is developed by ISO/TC 2, the technical committee for fastening elements.

Key Topics

• Grooved Pin Characteristics

  • Pins have three constant parallel grooves along their entire length.
  • The grooves are open-ended on one side and evenly spaced.
  • A raised collar (diameter d2) formed by material displacement provides a tight fit.
  • Diameter nominal range: 1.5 mm to 25 mm.
  • Materials covered: mild steel and austenitic stainless steel.

• Dimensions and Tolerances

  • Defined tolerances for nominal diameters and groove dimensions (e.g., h9, h11 tolerance classes).
  • Chamfer angles and groove angles specified to ensure compatibility and strain distribution.
  • Length ranges and specific mechanical shear strength values detailed.

• Material and Mechanical Properties

  • Mild steel and stainless steel grades specified according to ISO 3506-1.
  • Hardeness ranges from 125 HV 30 to 280 HV 30 depending on material and treatment.
  • Corrosion-resistant properties for stainless steel pins.

• Surface Finish and Coatings

  • Normal finish pins are supplied as manufactured with protective lubricant.
  • Preferred coatings include black oxide, phosphate layers, and zinc plating with chromate conversion.
  • All tolerances apply before any coating or surface treatment.

• Installation Guidelines

  • The drilled hole diameter must be equal to the nominal diameter of the pin with tolerance H11 for a proper interference fit.
  • The raised collar ensures a secure hold once the pin is driven into place.

• Testing and Quality Control

  • Routine shear testing as per ISO 8749.
  • Acceptance and inspection criteria follow ISO 3269.
  • Pins must be free from defects or irregularities that could impair function.

• Designation

  • Clear designation format includes standard number, nominal diameter, nominal length, and material code.
  • Example: Grooved Pin ISO 8739 - 6 · 50 - St for a mild steel pin 6 mm in diameter and 50 mm in length.
  • For stainless steel: Grooved Pin ISO 8739 - 6 · 50 - A1.

Applications

ISO 8739 grooved pins are essential components in mechanical assemblies that require secure, precise fastening with easy alignment. Typical applications include:

• Assembly of machinery and automotive parts.
• Fixing components in power tools and industrial equipment.
• Use in aerospace instrumentation where high-reliability fastening is critical.
• Situations requiring resistance to vibration and shear forces.
• Applications benefiting from corrosion resistance when stainless steel pins are used.

They are particularly well-suited for press-fit installations where mechanical strength and positional accuracy are important.

Related Standards

• ISO 3506-1 (1997) – Covers mechanical properties and corrosion resistance for stainless steel fasteners, including pins.
• ISO 8749 (1986) – Specifies shear testing methods for grooved pins.
• ISO 3269 (1988) – Guidelines for acceptance inspection and quality control of fasteners.
• ISO 4042 – Addresses electroplated coatings for fasteners to enhance corrosion protection.
• ISO 9717 (1990) – Defines phosphate conversion coating specifications applied on fasteners.

These complementary standards are key for manufacturers and engineers to ensure grooved pins meet comprehensive quality and performance requirements in line with international best practices.

Keywords: ISO 8739, grooved pins, full-length grooves, pilot end, parallel grooved pins, fastening elements, stainless steel pins, mild steel pins, mechanical fasteners, press fit pins, shear strength, corrosion-resistant pins, ISO standards.