ISO 6157-1:1988 PDF

Overview

ISO 6157-1:1988 - "Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements" defines permissible surface discontinuities and inspection principles for bolts, screws and studs used in general applications. It applies to fasteners with nominal thread diameters of 5 mm and larger, product grades A and B, and property classes up to and including 10.9. The standard establishes limits for defects (cracks, bursts, seams, voids, folds, tool marks, damages) and includes an annex sampling plan for acceptance inspection.

Key topics and technical requirements

• Scope and applicability: Covers bolts, screws and studs for general requirements; special or tighter limits (e.g., for automatic assembly) are covered in ISO 6157-3 or must be specified by purchaser/product standard.
• Types of surface discontinuities: Descriptions and causes of
  • Cracks (including quench cracks - expressly not permitted in any location)
  • Forging cracks and bursts and shear bursts
  • Seams and laps (raw material defects)
  • Voids (non-filled pockets from forging/upsetting)
  • Folds
  • Tool marks
  • Damages (dents, nicks, scrapes)
• Quantitative limits (examples given in the standard):
  • Voids: depth h