Rapid control of mold temperature during injection molding process

The control of mold surface temperature is an important factor that determines surface morphology and its dimension in thickness direction. It can also affect the frozen molecular orientation and the mold surface replicability in injection molded products. In this work, thin thermally active films were used to quickly control the mold surface temperature. In particular, an active high electrical conductivity carbon black loaded polyimide composites sandwiched between two insulating thin polymeric layers was used to condition the mold surface. By controlling the heating time, it was possible to control precisely the temporal variation of the mold temperature surface during the entire cycle. The surface heating rate was about 40 degrees C/s and upon contact with the polymer the surface temperature decreased back to 40 degrees C within about 5 s; the overall cycle time increased only slightly. The effect on cross section sample morphology of samples of iPP were analyzed and discussed on the basis of the recorded temperature evolution.