Cooling of injection moulds manufactured by machining has limitations because cooling channels are formed by conventional straight holes. With additive manufacturing, the cooling channels can be produced in the shape which is adjusted to the cavity and core surface of injection moulds. Those kinds of cooling channels are called the conformal cooling channels. Conformal cooling channels can significantly reduce cycle time of plastic injection moulding process and significantly improve the quality of products. Thus, in this work conformal cooling channels for industrial case study were constructed and analysed. Besides expected tests, cooling simulation has been performed, comparing conventional and proposed cooling technology. Results have been confirmed also by testing prototype with conformal cooling channels, showing significant improvement in reducing cycle time, more than 40 %.