Strong, conductive, endlessly reshaped — metals are the quiet backbone of everything from a power line to a piece of jewelry. Here's a look at the ones we rely on most, and the numbers behind them.
Machining figures are typical starting points for solid-carbide tooling with a Ø6 mm cutter — surface speed (Vc) is the real spec, so treat the rpm as an example that scales with tool diameter. Stiffness and thermal expansion are close to intrinsic, but tensile strength swings widely with alloy and temper, so those are shown as ranges. Always tune for your material and machine.
What makes a metal a metal is a shared set of behaviours: they conduct heat and electricity, they reflect light with that characteristic lustre, and — crucially — they bend and stretch without shattering. That last trait, ductility, is why metal can be drawn into wire, rolled into sheet, and forged into almost any shape we need.
Few are used pure. Most of the metal around you is an alloy — a blend tuned for a job. Iron becomes steel with a pinch of carbon; copper becomes bronze with tin, or brass with zinc. Mixing lets us trade a little of one property for a lot of another: more strength, less corrosion, a higher melting point.
And unlike most materials, metals are almost endlessly recyclable. A steel beam or an aluminium can be melted down and reborn with little loss — which is part of why these few elements keep building, and rebuilding, the world.