The development of additive manufacturing using metallic materials, such as the selective laser melting, has allowed the manufacture of free form cooling channels inside the molds for plastic injection. Reduction on the injection cycle time and product quality are expected using such cooling channels (also known as conformal cooling channels). The knowledge to design such cooling system are limited today. This work aims to collaborate with this issue. A new design of cooling channels using series and parallel concept are proposed and its efficiency were analyzed against some conformal cooling geometry found on the literature today. The analyses were carried out by a Computer Aided Engineering software using an automotive component as a workpiece. The results show that the design of the new approach of conformal cooling channels has an influence on the cooling performance and if the conformal cooling was not carefully designed, it cannot achieve the expected benefits. POLYM. ENG. SCI., 58:552-559, 2018. (c) 2017 Society of Plastics Engineers