ROLLING

Rolling is a shaping process by plastic deformation: the Metal passes between two cylinders rotating in opposite directions (the rolling mill), which progressively reduce its thickness and elongate it. Upstream of watchmaking, rolling transforms ingots and billets into strips, sheets or wires of controlled thickness, the raw material for cut or stamped components (plates, bridges, springs, dials, External parts (case, dial, hands) elements). A distinction is made between hot rolling, which does the rough shaping, and cold rolling, which gives fine dimensions, a good surface finish and work-hardens the metal, increasing its Hardness and its Elasticity — a property used in particular for springs and blades. The Testing of the thickness, flatness and surface condition of rolled strips is essential, as it determines the precision of subsequent Stamping and cutting operations. Rolling is part of the chain of processes for transforming Metals, alongside drawing (for wires and tubes), wire drawing and die forging. A poorly rolled strip compromises the entire downstream production.