Overview
ISO 7271:2011 - Aluminium and aluminium alloys - Foil and thin strip - Dimensional tolerances - specifies dimensional tolerances for aluminium and aluminium‑alloy foil and thin strip intended for general purposes. It applies to products shipped in rolls, covering double‑rolled foil (6 µm to 50 µm) and single‑rolled foil / thin strip (21 µm to 200 µm). The standard defines preferred thicknesses, thickness and width tolerances, measurement and arbitration methods, alloy groups for foil, and required ordering information.
Key topics and technical requirements
- Scope and product types: Double‑rolled foil (one bright side, one matt side) and single‑rolled foil/thin strip (both sides same).
- Preferred thicknesses: A list of preferred nominal thicknesses for double‑rolled foil (e.g., 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 25, 28, 30, 35, 40, 45, 50 µm) and covering areas based on density.
- Thickness tolerances:
- Tolerance on average thickness for a batch: ≤ 10 000 kg → ±10%, > 10 000 kg → ±8%.
- Point thickness tolerance: ±10% of nominal.
- Average and point thickness measurements require that more than 50% of measurements lie within ±5% of the average.
- Arbitration (gravimetric) method: For disputes, the standard prescribes a weighing method using a sample area of ≈1 dm², degreasing if necessary, balance accuracy ≈1 mg, dimensional measurement accuracy ±0.1 mm, and the gauge formula:
- E (µm) = (10 × M) / (A × D) where M = mass (mg), A = area (dm²), D = density (g/cm³).
- Width tolerances: Defined by nominal width; typical symmetric tolerances are ±1 mm for widths up to 1 000 mm and ±2 mm for widths over 1 000 mm; the standard also provides all‑plus or all‑minus tolerance options.
- Ordering information: Must include quantity (kg), alloy or minimum Al mass fraction, temper, thickness and tolerances, width, roll dimensions, core type/diameter and surface aspect (bright/matt).
Applications and users
ISO 7271:2011 is primarily used by:
- Aluminium foil and thin‑strip manufacturers and rolling mills
- Quality and inspection laboratories (material testing and arbitration)
- Purchasing/specification engineers and suppliers preparing contracts
- Industries using foil for packaging, electronics, thermal insulation and other general engineering applications that require controlled dimensional tolerances
Related standards
- Alloy designations referenced to international alloy registration (e.g., Aluminum Association “Teal Sheets”) and other ISO standards for wrought aluminium alloys (see Annex A for commonly used alloy groups: 1000, 3000, 5000 and 8000 series examples).
Keywords: ISO 7271:2011, aluminium foil tolerances, thin strip tolerances, thickness tolerances, width tolerances, gravimetric method, preferred thicknesses, aluminium alloy foil.
