ISO 8735:1997

Overview

ISO 8735:1997 specifies requirements for parallel (cylindrical) pins with internal thread, made of hardened steel and martensitic stainless steel. The standard covers nominal diameters from 6 mm to 50 mm and defines two main types: Type A (through‑hardened, with crown) and Type B (flat, case‑hardened). It provides dimensions, material and hardness requirements, surface finish and quality criteria, and example designation formats.

Key topics and technical requirements

• Diameter and length range: nominal diameters d = 6–50 mm; common nominal lengths listed (16 mm up to 200 mm and beyond in 20 mm steps).
• Types:
  • Type A: pins through‑hardened (also available in martensitic stainless steel C1).
  • Type B: case‑hardened (cemented) steel pins.
• Materials and composition: the standard gives compositional limits for the steels and the martensitic stainless variant (C1) and permits other materials by agreement.
• Hardness:
  • Through‑hardened pins: specified bulk and surface hardness ranges (e.g., 550–650 HV30 surface range referenced in the standard).
  • Case‑hardened pins: surface hardness and case depth requirements (minimum case hardness and typical case thickness specified).
• Thread and tolerances: internal threads follow metric ISO tolerances (metric threads, tolerance grade 6H per ISO 965‑2). Thread pitches and matching nominal thread sizes (M4–M24 depending on pin diameter) are listed.
• Surface quality and finish: surface roughness and absence of harmful defects required; coatings are permitted but must address hydrogen embrittlement risks and follow suitable post‑treatment (see ISO 4042).
• Inspection and acceptance: reception and inspection procedures reference ISO 3269.
• Designation examples: e.g., “Goupille cylindrique ISO 8735 – 6·30 – A – St” (hardened steel, 6×30 mm, Type A) or “Goupille cylindrique ISO 8735 – 6·30 – C1” (martensitic stainless C1).

Applications and users

• Typical applications: precise locating, alignment and load‑bearing dowel/pin applications in machinery, tooling, automotive assemblies, and precision equipment where controlled fit, strength and corrosion resistance are required.
• Who uses this standard:
  • Mechanical designers and engineers specifying pins for assemblies
  • Fastener and component manufacturers producing to ISO dimensions and hardness
  • Quality assurance and inspection teams verifying acceptance criteria
  • Procurement and supply chain professionals sourcing standardized pins

Related standards

• ISO 965‑2 - metric thread tolerances (6H)
• ISO 3269 - fasteners - acceptance inspection
• ISO 3506‑1 - mechanical properties of corrosion‑resistant stainless fasteners (reference for C1)
• ISO 4042 - electroplated coatings and hydrogen embrittlement precautions

Keywords: ISO 8735, parallel pins, parallel pins with internal thread, cylindrical pins, hardened steel pins, martensitic stainless steel, dowel pins, fastener standard, pin dimensions, thread tolerances.