GlossaryKind of term: Manufacturing termEN AW-2011 (free-machining aluminium)
What is EN AW-2011?
EN AW-2011 is an aluminium-copper alloy with bismuth and lead, made for turning: chips break short, but it welds poorly and resists corrosion badly.
EN AW-2011, chemical designation EN AW-Al Cu6BiPb, is a precipitation-hardening aluminium-copper alloy with small additions of bismuth and lead. These form fine, low-melting inclusions that make the chip break, hence the name free-machining aluminium. It is supplied mainly as drawn round, square or hexagon bar, for example in temper T3 or T8, for bar-fed turning, including on Swiss-type lathes.
What does the short chip of EN AW-2011 do?
Short chips allow high cutting speeds and feeds without long swarf wrapping round the tool and the part. That favours unattended turning, but whether a batch really runs unattended also depends on the bar feeder, chip evacuation, tool life and how dimensions are checked. The copper that gives the alloy its strength also makes it less corrosion-resistant than the 5xxx and 6xxx series, and gives a thinner anodic layer that protects less and colours less evenly. Fusion welding is not recommended because the alloy is prone to hot cracking.
What does the standard say about EN AW-2011?
The composition is in EN 573-3 and the temper designations in EN 515; mechanical properties of drawn bar are in EN 754-2 and of extruded bar in EN 755-2. Because 2011 contains lead, substance restrictions come into play, such as RoHS for electrical and electronic equipment, the rules for food contact materials and those for vehicles. Whether lead is permitted, and up to what content, depends on the regulation and the exemptions in force at the time. Lead-free free-machining alloys exist in the 2xxx and 6xxx series.
How does EN AW-2011 behave in the shop?
2011 suits series-turned parts such as bushes, pins, nipples and connector parts, where chip breaking and cycle time count for more than strength, corrosion resistance or appearance. Whether that advantage shows up in the cost depends on quantity, whether you run unattended, the bar price and the finishing. A part that has to be anodised, welded or used in a corrosive environment can come out cheaper in another alloy, even if it turns more slowly. If the drawing only says free-machining aluminium, ask which alloy is meant.
What is EN AW-2011 often confused with?
Free-machining aluminium is a collective name, not an alloy: 2011 is the best known, but other grades exist, some of them lead-free. Nor is it free-cutting steel: the principle is the same, inclusions that break the chip, but base metal, strength and finishes differ. And 2011 is not 6082: 6082 is the general-purpose alloy for milling and turning, better for welding and anodising, but with longer chips.
Frequently asked questions
Why is 2011 better than 6082 for unattended turning?
Because the bismuth and lead inclusions break the chip short. 6082 can produce long, stringy chips that wrap round the tool or the part. With a chip-breaking geometry, higher coolant pressure and adjusted cutting data, 6082 can often be controlled too, but with less margin.
Can you anodise EN AW-2011?
Yes, but the copper leaves a thinner, less protective layer with less even colour. Hard anodising is difficult. If the customer needs a decorative or protective layer, discuss the choice of alloy before quoting.
Can EN AW-2011 be used in electronics or in contact with food?
That depends on the lead content and on the regulation that applies, such as RoHS or the food contact rules, with their exemptions. Check this for each application. A lead-free free-machining alloy is a common alternative.