Overview
ISO 8747:1997 specifies the characteristics and dimensional requirements for grooved pins with countersunk head (three equally spaced longitudinal grooves) with nominal diameters from 1.4 mm to 20 mm. These pins are designed so the displaced material at the grooves produces an expanded diameter larger than the nominal diameter, creating a non‑positive locking fit when driven into a hole of nominal diameter (see clause 4). The standard covers two head/end types (Type A - chamfered end; Type B - pilot end) and includes dimensional tables, material and surface‑finish guidance, acceptance and designation rules.
Key topics and technical requirements
- Nominal size range: d = 1.4 mm to 20 mm inclusive (see Table 1 for detailed dimensions).
- Groove geometry: Three equally spaced grooves impressed longitudinally; grooving angle 70° specified for cold‑heading steel (may be modified for other, more resilient materials).
- Expanded diameter (d2): Larger than nominal d1; a GO/NO‑GO ring gauge is recommended for testing d2 (notes in Table 1).
- Hole fit: Mating hole diameter shall equal the pin nominal diameter and tolerance class H11.
- Materials and hardness: Preferred material is cold‑heading steel (St) with hardness 125 HV30 to 245 HV30; other materials by agreement between supplier and customer.
- Surface finish & coatings: Pins supplied plain with protective lubricant unless otherwise specified. Preferred coatings: black oxide, phosphate coating, or zinc plating with chromate conversion (see ISO 9717 and ISO 4042). All tolerances apply prior to plating/coating.
- Workmanship & acceptability: Pins must be free of detrimental defects; acceptance inspection per ISO 3269.
- Designation format: Example - Grooved pin ISO 8747 – 6 · 30 – St (append type A/B if required).
Applications and who uses this standard
ISO 8747 is used by:
- Fastener manufacturers for production and quality control of countersunk grooved pins.
- Design and mechanical engineers specifying reliable, standardised pins for assemblies.
- Procurement and quality inspectors verifying incoming parts to defined dimensional and acceptance criteria.
- Typical applications include mechanical assemblies where a non‑positive interference fit is required for location or light retention in machinery, electronics housings, automotive components and general engineering fixtures.
Related standards
- ISO 3269 - Fasteners: acceptance inspection.
- ISO 4042 - Fasteners: electroplated coatings (revision reference).
- ISO 9717 - Phosphate conversion coatings for metals.
Keywords: ISO 8747, grooved pins with countersunk head, grooved pins, fasteners, expanded diameter, H11 tolerance, cold‑heading steel, pin dimensions, ISO 3269, ISO 4042, ISO 9717.