A CNC wire bender takes a straight length of steel and produces a finished three dimensional part in under two seconds. The machine looks crude. The physics governing it is anything but. Wire arrives off a spool carrying residual curvature from being wound. Before anything can be formed, that memory has to be erased. The wire is dragged through two orthogonal sets of offset rollers, each one plastically overworking the material past its yield point so it emerges genuinely straight rather than merely bent the other way. From there the sequence is deceptively simple: - Servo driven pinch rollers advance the wire, with an encoder counting developed length to a fraction of a millimetre - A bend head rotates a forming pin around a fixed mandrel, wrapping the wire to a radius set by the tooling - Between bends, either the wire rotates about its own axis or the head orbits it, placing the next bend in a new plane The difficulty is springback. Bending is elastic and plastic at once. The ou...