ISO 12686:1999 PDF

Overview

ISO 12686:1999 - "Metallic and other inorganic coatings - Automated controlled shot-peening of metallic articles prior to nickel, autocatalytic nickel or chromium plating, or as a final finish" - defines requirements for automated controlled shot-peening used before or after nickel or chromium plating. The standard covers selection and conditioning of shot (cast steel, conditioned cut wire, ceramic shot, glass beads), process control (intensity, saturation, coverage), and verification methods (Almen strips, gauges, calibration). It specifically excludes hand-peening and rotary flap-peening and is usually not suitable for brittle materials.

Key topics and technical requirements

• Shot materials and form: permitted media are cast steel, cut wire, ceramic shot and glass beads. Shot must be spherical after conditioning and free of sharp edges or broken pieces.
• Hardness requirements: cast steel shot typically HRC 45–55 (special hard 55–65); cut-wire minimum hardness varies by size (about HRC 36–48); ceramic shot ≥ 560 HV30; glass beads ≈ Mohs 5.5.
• Size and conditioning: shot size must produce required intensity and meet sieve/screening requirements. New cast steel charges require conditioning (minimum passes) to remove oxides.
• Process control parameters: intensity (measured by Almen strip arc height at saturation), saturation curves, coverage percentage, shot flow, air/wheel speed, nozzle position, peening time and process-interrupt parameters.
• Measurement & verification: use of Almen strips, holders and gauges, calibration systems and tests for freedom from iron contamination (see Annex A–F normative).
• Effects on material: shot-peening induces residual compressive stresses and changes near-surface microstructure (can include phase transformation), helping to limit plating-induced fatigue reduction or increase fatigue life for unplated parts.

Applications

• Improving fatigue life, resistance to stress-corrosion cracking, and dimensional correction of machined parts prior to electrolytic or autocatalytic nickel or chromium plating.
• Final surface finish for components in automotive, aerospace, bearing, tooling, and heavy engineering where plated surfaces can reduce fatigue performance unless peened and controlled.
• Situations requiring documented, repeatable, automated processes with traceable intensity and coverage records.

Who uses this standard

• Plating shops, surface-treatment specialists, metallurgists, process engineers, quality managers and OEMs that specify controlled shot-peening before/after nickel or chromium plating.
• Machine builders and integrators of microprocessor-controlled peening systems and inspection labs performing Almen testing and certification.

Related standards

ISO 12686 references test-sieve and inspection standards (e.g., ISO 565, ISO 3310-1) and includes normative annexes (A–F) and informative Annex G for guidance. Use ISO 12686:1999 alongside material-specific fatigue or plating specifications for full process control.

Keywords: ISO 12686:1999, shot-peening, automated controlled shot-peening, nickel plating, chromium plating, Almen strip, cast steel shot, cut wire shot, ceramic shot, glass beads, residual compressive stresses, fatigue life.