About 2011|The free-machining aluminum. Lead and bismuth additions make this the closest thing aluminum has to 12L14 steel — chips break clean, surface finish is excellent, and tools last. Rated at around 90% machinability, tied with
6262 for the top spot among aluminum alloys. The tradeoff is corrosion resistance (worse than
6061) and it’s essentially non-weldable. Used for high-volume screw machine parts: fittings, connectors, precision bushings, and anything that comes off an automatic lathe. If you’re making 10,000 aluminum parts on a Swiss machine, spec 2011. Compare to 6262 (similar machinability, better corrosion resistance) and 6061 (standard shop alloy, much gummier to machine).