The induction coil is the heart of the induction furnace, induction coil by medium frequency power supply, have a strong magnetic field in the medium frequency power supply, electric current, the magnetic field in the hearth of the metal to produce eddy current heating, induction coil is the key to energy conversion. So the coil design is particularly important. The original induction wire tube tube production process using general electrolytic copper by melting and casting, extrusion and heating into standard, after repeated stretching to the standard tube, after molding tensile, finally with no protection type heating annealing production in rectangular conduit. The research and development of new technology, it is made of high quality steel ingot, electrolytic copper smelting, heating extrusion into standard production, then forming a D type wire tube rolling with eccentric compression method, and then through the induction furnace heating annealing and gas protection to produce smooth and bright surface clean conduit. Effectively improve the efficiency and save energy. This is a new breakthrough for electric sensor.