ISO 7297:1985

Overview

ISO 7297:1985 defines the mechanical, physical and magnetic characteristics of a lubricated magnetic disk intended for data storage devices with a nominal outer diameter of 200 mm (7.9 in) and inner diameter 63.5 mm (2.5 in). The standard (prepared by ISO/TC 97) specifies requirements to give satisfactory performance at approximately 95 840 flux transitions per track (title nominally cites 96 000). First published in 1985, ISO 7297 covers dimensional tolerances, environmental and operating conditions, surface quality, magnetic testing and durability criteria for high‑density disk media.

Key topics and technical requirements

• Dimensional and mechanical: outer diameter d3 = 200.00 ± 0.10 mm; inner diameter d2 = 63.500 ± 0.005 mm; thickness 1.905 ± 0.025 mm; concentricity and circularity limits; clamping area specifications.
• Environmental / storage: operating air temperature 15–57 °C, storage −40 to +65 °C; ambient stray field limit at disk surface not to exceed 4 000 A/m (reduced when heads concentrate fields).
• Surface quality: magnetic surfaces roughness < 0.025 µm Ra; undulation peak‑to‑peak < 0.15 µm; clamping area roughness < 0.8 µm Ra.
• Magnetic and track parameters: effective track width for testing 40 ± 4 µm; tested area radii and track spacing defined for 95 840 transitions/track; discharge path requirements so charges flow to clamping area.
• Runout and dynamics: axial runout ≤ 0.076 mm up to 4 000 r/min; velocity and acceleration limits for axial runout; disk must survive rotational stress at 7 000 r/min.
• Friction and wear: dynamic coefficient ≤ 0.200 (peak‑to‑peak variation ≤ 0.035); static coefficient ≤ 1.0 after 48 h stationary contact; durability test of 10 000 head take‑off/land cycles.
• Test heads and calibration: defined test head parameters (gap length, inductance, loading) and calibration to a Standard reference surface; annexes A–C detail air cleanliness class, head/disk friction method and effective track width measurement.
• References: ISO 1202 and ISO 1302 referenced for related measurements and surface texture notation.

Applications and who uses ISO 7297

• Disk media manufacturers and coatings suppliers for product specification and quality control.
• Hard disk drive (HDD) designers, test laboratories and QA teams validating mechanical and magnetic compatibility.
• Suppliers and buyers setting procurement and acceptance criteria for 200 mm high‑density magnetic disks.
• Archives and organizations maintaining legacy magnetic media who need formal specifications for storage, testing and preservation.

Related standards

• ISO 1202 (referenced) and ISO 1302 (surface texture notation). Annexes A–C in ISO 7297 give procedural detail for cleanliness, friction testing and track‑width measurement.

Keywords: ISO 7297, magnetic disk standard, 200 mm disk, 96 000 flux transitions per track, disk surface roughness, runout, data storage media, magnetic characteristics.