The cooling time in injection and blow molding processes is a crucial factor for economic success. Since unfilled polymers show a low thermal conductivity compared to metals – due to the lack of free electrons - the polymer dominates the cooling efficiency, intensely for thick-walled part geometries. The aim of this study was to increase both the thermal conductivity λ and the thermal diffusivity of high density polyethylene (λ = 0.44 Wm-1K-1) by adding a suitable filler system up to a filler content of 30 vol.%. In a first test series the influence of the filler content on the thermal conductivity was determined. SiO2 filler showed a linear increase of the thermal conductivity with rising filler content, which is in good agreement with calculated values using the Maxwell- and Lewis-Nielsen-Modell. In a second test series, the filler content was set to 30 vol.%. The influence of numerous filler types as well as mixtures of fillers (polymer + filler1 + filler2) was analyzed. For combined-filler compounds, no synergetic effect was found, in contrast to other studies. However, adding hexagonal boron nitride increased λ by 900%. In a third test series three compounds were injection molded, which leads to an inhomogeneous filler distribution if anisotropic filler particles (L/D >> 1, e.g. talcum) are used. While CaCO3 and SiO2 (L/D = 1) yields almost isotropic thermal conductivity, analyzing core and surface sections of talcum compound specimens proved, as expected, the anisotropic filler distribution over the part thickness. Calculating the cooling time for a 4mm thick part, compared to unfilled HDPE, reductions by 45% and 35% were estimated using 30 vol.% of SiO2 and CaCO3 respectively. In conclusion, thermal conductive polymers increase the production efficiency of injection molding. Further studies on improved mechanical performance will be published elsewhere.