passage 221 and the holding platform 23 on the holding platform 23 there is a first push device 25 for moving the iron cores 40 a 40 b to the machining platform 24 on the machining platform 24 there is a cutting mechanism 30 which includes an electric driving device 31 a rotary shaft 32 driven by the electric driving device 31 and cutters 33 mounted on the rotary shaft 32 for cutting the air gaps 41 a 41 b on the iron cores 40 a 40 b referring to fig2 a and 2b the material holding area 21 further has a plurality of sensors 11 a 11 b and 11 c for detecting moving paths of the iron cores 40 a 40 b and generating signals to the electronic control box 10 when the iron cores 40 a 40 b are dropped to the holding platform 23 from the transporting passage 221 and tube 222 the sensor 11 b on the material holding area 21 detects the iron cores 40 a 40 b and generates signals to notify the electronic control box 10 the electronic control box 10 synchronously generates signals to activate the transmission system 20 to move the.