Slow wire is the use of continuous moving fine metal wire (called electrode wire, generally copper wire) as an electrode, pulse spark discharge on the workpiece, produce more than 6000 degrees of high temperature, corrosion of metal, cutting into the workpiece of a CNC processing machine. The principle of slow wire processing is that there is a gap between the online electrode and the workpiece, and the phenomenon of continuous discharge removes the metal. A set of water circulation system is used to purify water quality and deion to achieve the role of working liquid reprocessing.