bar stock
Portions of metal (stock) in the form of bars, suitable for machining (such as turning) or fabrication (such as welding). It comes in standard cross-sections and certain lengths, such as 6 to 12 feet.
bar stock: metal in standard profiles, ready to machine
Bar stock is metal supplied in long, straight pieces with uniform cross-sectional profiles. It arrives ready for immediate use in turning, milling, forging, or welding operations, eliminating the need to cast or extrude custom shapes in-house. Common lengths run 6 to 12 feet, though vendors stock shorter and longer lengths depending on material and cross-section.
The cross-sectional profiles follow industry standards. Round bar is the most common, available in diameter increments of 0.125 inches from 0.25 inches up to several inches. Flat bar comes in standard widths and thicknesses, typically 0.125 to 2 inches thick. Square bar, hexagonal bar, and angle iron are stocked routinely. Specialty profiles such as T-stock, channel, and I-beam are less frequently kept on hand but can be ordered. The material itself varies widely: mild steel, stainless steel grades (304, 316, 410), aluminum alloys, brass, copper, and tool steel all come in bar form.
Machinists favor bar stock because the geometry is already established. A CNC lathe can load a 1-inch diameter rod and begin turning without setup delays. The stock profile determines how much material must be removed; a round bar requires less facing than a square bar of equivalent weight. When stock diameter or thickness exceeds the final part dimension significantly, chip load increases and tool life drops, making oversized bar wasteful. Selecting the closest standard size reduces both tool wear and scrap.
Supply chains and defects
Bar stock moves through distributors who cut bulk lengths to customer specifications. A 12-foot length might be cut into three 4-foot pieces or six 2-foot pieces for a job shop. The cut surfaces show oxidation or saw marks that must be cleaned before finish machining. Surface finish varies by rolling mill and material; cold-drawn bar is smoother and more dimensionally consistent than hot-rolled, but costs more. Centerline segregation and internal porosity are rare in modern bar stock but must be monitored in critical applications, particularly in tool steel.
The term 'stock' reflects its role in inventory control. A job shop holds a range of standard profiles and diameters in common materials, pulling from inventory as jobs arrive rather than waiting for custom extrusions. This approach keeps material cost down and lead time short but commits floor space and working capital to inventory. The alternative, ordering only to job specification, saves storage space but delays projects and usually incurs a minimum order penalty from the supplier.