Effect of Coil Geometry on Induction Heating for Injection Mold Part

In this study, a sample mold plate was used to test an induction heating system with different coil designs. Four coil configurations, parallel, spiral, 3D, and serial coil, were constructed for the induction heating process. The mold surface temperature was heated in 2 s. The temperature at three points and the temperature distribution on the heating surface were then collected to evaluate the effect of the coil geometry on the induction heating process. At the same heating power, the spiral coil has the highest heating rate of 35.5 degrees C/s, followed by the 3D coil at 25.5 degrees C/s. In addition, the spiral coil creates a ring-shaped high temperature area while the 3D coil creates a rectangular high temperature area. The 3D coil also exhibits better temperature uniformity than the spiral coil, which reduced the temperature difference between 3 points from 41 degrees C (spiral coil) to 23 degrees C (3D coil). Results also show that the heating effect of the parallel and serial coil are not good enough for use in the injection molding process. By using the 3D coil, double sided heating was achieved with positive results. Although the heating rate of the double sided heating is not as high as with single sided heating because of the larger area that must be heated, the temperature difference between three points fell from 23 degrees C to 17.5 degrees C in the experiment when double sided heating was used.