1100 is the workhorse of the 1xxx "commercially pure" series, guaranteeing a minimum of 99.0% aluminum by weight — the lowest purity floor in the group, and the one deliberately alloyed with a small, controlled addition of copper (0.05–0.20%) to nudge up strength slightly over unalloyed 1050 or 1070. That small copper addition doesn't make 1100 heat-treatable; like the rest of the 1xxx family, it firms up only through cold working, and even in hardened tempers it remains a soft, low-strength material next to any 2xxx, 6xxx, or 7xxx alloy.

What 1100 trades away in strength, it recovers in formability, corrosion resistance, and excellent electrical and thermal conductivity. It's one of the most widely available and least expensive aluminum grades on the market, commonly used for spun and deep-drawn parts, chemical process and food equipment, heat exchanger fins, nameplates, foil, and general sheet metal fabrication where cost and workability matter more than mechanical performance. Shops often reach for 1100 specifically because it forms, welds, and finishes easily — not because it's expected to carry structural load.

1100's small copper addition takes the edge off the extreme gumminess seen in 1050, 1070, and 1080, but it's still a soft, low-strength material and the same core problem applies: it doesn't shear cleanly, it smears. Low strength combined with high ductility means the material deforms plastically ahead of the cutting edge rather than fracturing into a clean chip, which promotes built-up edge (BUE) — aluminum welding onto the insert and then tearing back off, degrading surface finish and dimensional control.

The fix is the same discipline that applies across the whole 1xxx family: keep cutting edges sharp and polished rather than honed, use high positive rake angles to shear rather than push through the material, and run at the higher end of the recommended speed range instead of throttling back. Slower speeds give the material more time to stick to the tool — exactly the opposite of what "soft material, go easy" intuition suggests. Adequate coolant or air blast helps keep the cutting zone clean and reduces the chance of chips re-welding to the workpiece.

1100 still produces long, continuous chips that need active breaking, though slightly less aggressively stringy than the purer 1xxx grades thanks to the copper content. A chipbreaker geometry designed for non-ferrous materials, paired with feed rates high enough to keep the chip from ribboning out indefinitely, is the standard approach for keeping chip control manageable.