bar

A bar is a length of metal drawn, rolled, or extruded to a uniform cross-section, whether round, square, hexagonal, octagonal, or rectangular. It begins as cast metal, usually an ingot, which is then hot-worked through rolling mills or draw benches to create a product of consistent profile and much smaller cross-sectional area. In North American practice, anything with a smallest dimension of 1/4 inch or greater qualifies as a bar; thinner material falls under the classification of strip or foil.

Bars serve as the primary intermediate product between raw casting and finished parts or further processing. A round bar, or rod, might be drawn from mild steel, stainless steel, aluminum, or copper alloys and used directly for shafts, bolts, or mandrels, or cut into billets for forging. Square and rectangular bars enter stamping presses, CNC mills, or are cut to length and ground for precision applications. Hexagonal and octagonal profiles are less common and typically serve specialized fastener or tool applications.

The term carries weight in trade because it signals a specific stage of the value chain. A bar represents material that has already undergone significant thermomechanical work, conferring directional grain structure and mechanical properties superior to cast stock. When a supplier quotes 'bar stock' rather than 'billet' or 'slab', they are confirming that surface condition and dimensional tolerance have met working standards, though not necessarily finished tolerances.

Common defects in bar stock include surface scale, seams (subsurface longitudinal cracks from ingot segregation), and dimensional runout. The profile dimension varies within accepted limits, typically plus-or-minus a few thousandths of an inch depending on size and material. Stainless bars require controlled cooling after rolling to avoid sensitization; carbon steel bars may be normalized or annealed depending on intended use.

The distinction between bar and strip is not semantic but commercial and functional. A 0.125-inch-thick piece of steel would be called strip and sold by the pound or coil; a 0.250-inch hexagonal rod is a bar and sold by the foot or by the piece. This boundary matters for pricing, handling, and the machines that will consume it. Wire is a separate category altogether, typically cold-drawn and coiled, produced in diameters below 1/4 inch.