8011 Aluminium Foil at a Glance: Alloy and Temper
8011 aluminium foil is an aluminium-iron-silicon alloy supplied to EN 573-3 as EN AW-8011. Its composition is built around Si 0.50-0.90% and Fe 0.60-1.00%, with Cu, Mn, Mg, Cr, Ni and Zn each limited to low maxima, typically 0.10, 0.20, 0.05, 0.05, 0.05 and 0.10% respectively, and Ti capped at 0.08%. The alloy is not heat treatable, so all strength comes from work hardening and from control of the rolling and annealing schedule.
Foil is normally delivered in O, H14, H16, H18, H22, H24 and H26 tempers, in thicknesses from about 0.006 mm to 0.2 mm and web widths up to roughly 1500 mm. Typical reference standards are EN 546 for aluminium foil, GB/T 3198 for foil of general engineering grades and ASTM B479 where barrier foil properties are specified. Because the whole converting line downstream of the mill depends on repeatable incoming properties, the alloy and temper specification already determines most of the processing behaviour.
Formability and Its Effect on Rolling and Annealing
Formability is the first property that shapes processing technology. In the O temper 8011 foil is soft and highly ductile, with elongation well above that of harder tempers, so it can be wound, printed, lacquered and formed into container lids or blister pockets without tearing. As the material is work hardened towards H18 it gains tensile strength and load-bearing capacity but loses elongation, so deep drawing and fine embossing operations must be run in softer tempers.
At the mill this translates into control of the reduction per pass, front and back tension, rolling speed and the total reduction before intermediate annealing. A schedule that pushes reduction too hard produces edge cracking, bright banding and residual stresses; a schedule that under-rolls forces extra passes and raises the risk of thickness drift. Intermediate and final anneals soften the work-hardened metal, relieve stresses before formability-critical operations and stabilise the temper so that the mechanical properties quoted on the certificate are reproducible from coil to coil.
Thermal Conductivity, Surface Quality and Coating Behaviour
The thermal conductivity of 8011 foil is close to that of pure aluminium, in the region of 200 W/m·K at room temperature, with density around 2.71 g/cm³. In converting lines this high conductivity is a real advantage: heat applied in lacquering and printing ovens is distributed quickly across the web, so drying and curing can be run faster and at lower oven energy input, and heat seal and lamination steps reach bonding temperature more evenly across the web width.
Surface quality is the second driver. Foil intended for lacquering, printing or lamination must be free of roll marks, pinholes, oxide streaks and residual rolling oil, because any of these causes coating skips, pinholes and adhesion failures. Surface treatments such as cleaning, chemical conversion coating or corona treatment raise the surface energy so that lacquer and adhesive wet out evenly.
Corrosion Resistance and Compatibility with Downstream Use
With low copper content and a fine dispersion of iron and silicon phases, 8011 resists atmospheric and food-contact corrosion well, which is why it is common in pharmaceutical blister lamination, container lids, dairy closures and food packaging. Resistance improves further when the foil surface stays clean and dry and when it is coated or laminated so that aggressive media never reach bare metal.
In heat-exchanger fin stock and other thermally cycled applications, corrosion resistance and formability work together with fin stiffness. A foil that forms crisp fins but corrodes at the fin roots will fail early, so the temper, surface treatment and any applied coating must be matched across the whole package rather than optimised one property at a time.
The Practical Process Window
Recommended practice on a converting line handling 8011 foil:
Hold rolling-oil temperature, viscosity and filtration within a tight band, since oil film thickness controls friction, roll forces and surface brightness.
Control web tension independently on unwind and rewind; excessive tension produces coil collapse and stretcher strains, too little causes telescoping and wrinkles.
Keep the roughness and crown of the work rolls matched to the target finish and to the thickness tolerance required.
Verify annealing soak temperature and time so that the temper reported on the certificate matches the temper delivered.
Condition the surface immediately before lacquering, printing or laminating, and check wetting with a simple test ink or dyne test.
Monitor flatness and thickness continuously at the exit of the mill; flatness defects found later on the converting line are far more expensive to correct.
Frequently Asked Questions
Q: What are the key properties of 8011 aluminium foil?
Good formability, high thermal conductivity, corrosion resistance, low density and reliable surface quality for coating and lamination. Together these decide how the foil behaves in rolling, annealing and converting.
Q: How do material properties affect the processing technology?
High conductivity shortens oven cycles and evens out heat seal temperatures; high formability widens the drawing and embossing window. Harder tempers raise strength but narrow the forming window.
Q: Which tempers are used for which process?
O and H22/H24 tempers suit deep forming, lacquering and lamination. H14 and H16 balance strength with forming. H18 gives the highest stiffness for fins and lids where forming strain is low.
Q: Why does 8011 foil blister or show coating defects?
Usually because of residual rolling oil, oxide streaks or trapped moisture, or because of an unstable annealing schedule. Clean surface condition and controlled lubrication remove most of these defects.
Q: How does foil performance influence finished product quality?
A foil with consistent thickness, flatness and temper produces better dimensional accuracy and adhesion, less breakage on high-speed lines and more predictable barrier and mechanical performance in the finished pack.
Q: What should be checked when receiving a coil of 8011 foil?
Check the certificate for alloy, temper and mechanical properties, measure thickness and width at several points, inspect surface for roll marks and pinholes, and confirm the coil ID and mass match the order.
