PROFILE TURNING

Profile turning encompasses all metal-cutting machining operations — primarily turning, but also threading, tapping, drilling, or milling — carried out in continuous series from a bar of metal set in rotation, on automatic lathes called profile turning machines. The name comes from the original gesture: “décolleter” a part, meaning to reduce its collet, its narrowest section, by turning. Cam-type profile turning machines machine each part in succession from the bar using a set of cams synchronized with the spindle; recent CNC models replace these cams with servo-controlled axes. Horologist (watchmaker) profile turning is characterized by the very small size of the parts produced — screws, rods, pivots, sleeves, rough-machined pinions — and by dimensional tolerances that can go down to the micron, obtained from brasses or steels known as “free-cutting steels”, chosen for their good machinability. Historical birthplace of this technique in the 19th century, the Swiss Jura Arc (cantons of Solothurn, Jura, Neuchâtel and Bernese Jura) remains today one of the world centers, alongside the French Arve valley. Profile-turned parts generally undergo additional heat treatments or surface treatments before their assembly in the Movement.