Overview
EN ISO 11381:2016 (Ophthalmic optics - Spectacle frames - Screw threads) specifies ISO metric screw-thread requirements for spectacle-frame use. Published by CEN and identical to ISO 11381:2016, it covers nominal screw sizes, classes of fit, length tolerances, and requirements for related taps and gauges used in ophthalmic optics and spectacle-frame manufacture.
Key topics and technical requirements
- Scope: Applies to ISO metric screw threads for spectacle frames in sizes:
- S0,8 × 0,2; M1,0 × 0,25; M1,2 × 0,25; M1,4 × 0,3; M1,6 × 0,35; M2,0 × 0,4.
- Thread types and standards:
- S0,8 × 0,2 complies with ISO 1501 (miniature threads).
- M1.0–M2.0 sizes comply with ISO 965-3 (tolerances for constructional threads).
- Class of fit: Specifies nut and screw tolerance classes (example: M1.6 × 0.35 – 6H/6h). Table of classes assigns tolerance grades/positions per thread size.
- Screw head and length definitions:
- Clear definitions for flat head, countersunk, fillister (raised countersunk), pan and cheese head screw lengths (including chamfers/radii).
- Tolerance on length: nominal length tolerance is 0 mm to −0.15 mm unless otherwise specified by purchaser.
- Screwing taps and gauges:
- Taps for M1.0–M2.0 comply with ISO 529; S0.8 × 0.2 taps are not specified by an international standard.
- Gauges must comply with ISO 1502.
- Annex A (informative): Maps typical screw sizes to frame uses (e.g., pads, joints, closing blocks).
Practical applications and users
- Who uses this standard:
- Spectacle-frame manufacturers and component suppliers
- Product designers and mechanical engineers in ophthalmic optics
- Quality assurance and inspection laboratories
- Tooling and fastener producers supplying miniature screws, taps and gauges
- Standards bodies and procurement teams specifying compliant components
- Why it matters:
- Ensures interchangeability and reliable assembly of tiny fasteners in eyewear
- Reduces rejects and warranty issues due to incompatible threads or incorrect tolerances
- Guides selection of taps and gauges for production and inspection
Related standards
- ISO 1501 - Miniature screw threads
- ISO 965-3 - Metric screw thread tolerances (constructional)
- ISO 529 - Short machine taps and hand taps
- ISO 1502 - Gauges and gauging for metric threads
EN ISO 11381:2016 is essential for anyone specifying or producing screw threads for spectacle frames, ensuring consistent thread geometry, fit classes, and length tolerances across the ophthalmic optics supply chain.
