Bar turning (décolletage in French) is the high-volume machining of small parts of revolution cut from a bar or wire fed into the machine. The automatic lathes that do it combine turning, drilling, milling, tapping and parting-off, and the part comes out finished, most often with no further operation. In France, the Arve valley in Haute-Savoie is its historic birthplace.
The emblematic machine is the sliding-head lathe, often called a “Swiss-type lathe”: the bar is guided in a bush very close to the tool and it is the bar that advances, which limits deflection and allows long, slender parts to be machined accurately. A sub-spindle picks up the part to work the other end. Multi-spindle machines, which machine several parts in parallel, reach very high rates, and cam-driven automatics long dominated high-volume work. Today CNC equips most machines, which makes changeovers faster.
Bar-turned parts include screws, pins, dowels, end fittings, connectors, electrical contacts, watch components, connector elements, instruments and medical implants. Materials are most often brass, free-machining steels, aluminium and stainless steel. For small runs, CNC turning is often more economical; from several thousand parts upwards, bar turning generally has the advantage. The guide on bar turning or CNC turning details this choice; for bar-turned parts, see also CNC machining.
In a quote request. State the annual quantity and batch size, the bar diameter, the part length, the material, and the dimensions with their tolerances. Specify the edge condition (deburring), the surface finish, the level of in-process inspection expected and the delivery method (loose, tubes or trays), which affects handling as well as price.