Development of an Injection Nozzle Heating System for the Production of Automotive Control Cables

Control cables are crucial in automobiles, facilitating door and window operation, as well as the engagement of the handbrake and accelerator. The terminals of these control cables are small die-cast parts typically manufactured from light and low-melting point alloys, predominantly zamak. During the injection process, issues related to the heating of the injection nozzle are common, leading to challenges in extracting the control cable terminal from the injection mold. This work aims to develop a new solution for heating zamak alloy injection nozzles by electromagnetic induction for the manufacture of control cable terminals. Heating is normally carried out by electric resistors, which do not assure precise control of the components’ temperature or a rapid response to variations in the injection nozzle temperature. An induction heating solution was proposed in this work as replacement with a frequency of 155 kHz and power of 410 W, in which the electric current is transmitted by an external circuit to a multi-coil solenoid-shaped inductor, which is ideal for workpieces with cylindrical geometry, and the temperature is measured by a pyrometer. The necessary temperature provided to the injection set to assure the required 550 ºC in the injection nozzle was estimated by the Finite Element Method as 600 ºC. The calculated return-on-investment was shortly below 13 years.