Hexagonal cross-section bar to ASTM A479 / A276 for nut blanks, hex-fitting bodies, and CNC-lathe-friendly stock
Hex bar is the natural feedstock when the finished part already has a hexagonal profile and the manufacturer wants to skip the milling pass that would otherwise turn round bar into hex. Nuts (regular and heavy hex), hex pipe plugs, hex fitting bodies, and CNC-lathe blanks for hex-headed components are typically machined directly from across-flats hex bar. Ferralium 255 (UNS S32550, EN 1.4507) hex bar covers 6 mm to 100 mm across-flats per ASTM A479 / A276 and the metric series per EN 10088-3, supplied solution-annealed at 1080 °C with water quench, ferrite content within the 35 to 55% qualifying band. Per-heat EN 10204 type 3.2 MTC. RFQ: info@torqbolt.com / WhatsApp +91-22-66157017.
| Across-flats (AF) | Tolerance class | Length | Use case |
|---|---|---|---|
| 6 mm to 14 mm | ISO h11 (cold-drawn) | up to 6 m | Small fastener and instrumentation hex parts |
| 14 mm to 36 mm | ISO h11 (cold-drawn) | up to 6 m | Standard hex nut feedstock M10 to M30 |
| 36 mm to 75 mm | ISO h12 (peeled / hot-rolled) | up to 6 m | Heavy hex nut feedstock M36 to M64 |
| 75 mm to 100 mm | ISO h13 (hot-rolled) | up to 4 m | Large hex valve plug and fitting blanks |
For finished parts with a hex profile (nuts, plugs, fittings) the hex bar feedstock saves one or more secondary operations. A 50 mm AF hex bar machined to a finished M30 heavy hex nut requires only ID-drilling and tapping plus the chamfer, while the same nut started from 60 mm round bar needs an additional 6-flat milling operation. The cost saving is typically 15 to 30% of finished-part cycle time at moderate volumes (above 100 pieces per heat). For very low volume (below 50 pieces) round bar is often more economical because the inventory carrying cost of multiple AF sizes outweighs the milling saving.
