Overview
ISO 18684:2020 - Timekeeping instruments - Watch external parts made of hard material - General requirements and test methods defines performance and test methods for watch external parts (cases, bezels, crowns, bracelets, clasps) made of hard materials (massive components with Vickers hardness ≥ 1 200 HV). The standard excludes watch glasses and focuses on resistance to mechanical and thermal shocks, corrosion, wear, scratches, impact and sunlight exposure. It also covers inspection principles, sampling statistics and practical acceptance guidance for horological components.
Key topics and requirements
- Scope and definitions: Applies to massive hard-material components (≥ 1 200 HV); notes potential allergens (nickel, cobalt) and prohibits harmful shapes.
- Mechanical shock resistance: Follows ISO 1413 requirements with a reduced drop height of 0.75 m for hard materials; acceptance - no functional or cosmetic failures.
- Thermal shock: Cyclic test - soak at 70 °C ±2 °C (2 h) then immersion in 5 °C ±2 °C water for ≥30 s, repeated at least five cycles; no visible degradation allowed.
- Corrosion resistance: Uses methods from ISO 9227:2017 (salt spray) and ISO 3160‑2:2015; acceptance criteria set by concerned parties.
- Wear and scratch resistance: Uses ISO 23160:2011 procedures; scratch tests use sharp-edge alumina abrasive Corundum F70 (Dv ~210 µm, hardness ≈ 1 900 HV).
- Impact resistance & accidental damage: Tests per ISO 23160 for impacts, falls and luggage friction; acceptance per ISO 23160.
- Sunlight (colour) stability: Climatic/light exposure using filtered Xenon/metal halide lamps with controlled irradiance and airflow (per ISO 4892 guidance).
- Statistical sampling & inspection: Recommends statistical approaches (Annex C) due to brittleness variability; includes annexes on hard materials, test examples and inspection rules.
Applications
ISO 18684:2020 is practical for:
- Watch manufacturers designing and validating cases, bezels, crowns, bracelets and clasps made from tungsten carbide, technical ceramics and similar hard materials.
- Component suppliers and material producers establishing material specifications (≥ 1 200 HV) and quality-control tests.
- Quality assurance and test laboratories performing standardized shock, corrosion, wear, scratch and sunlight tests.
- Design and compliance teams assessing durability, consumer safety and product claims (scratch resistance, wear life).
- Regulatory and procurement specialists requiring harmonized test evidence for sourcing and conformity.
Related standards
ISO 18684:2020 provides targeted test methods and acceptance guidance for durable, high‑hardness watch components - essential reading for horology professionals working with tungsten carbide, ceramics and other hard materials.