Due to the demand for short product development cycles, plastic injection mould designers are required to compress their design time and to accommodate more late changes. This paper describes an associative design approach embedded in a cooling channel module of a mould design software package. It gives a set of comprehensive object definitions for cooling circuits, and addresses balanced or unbalanced designs. CAD algorithms that have been developed are briefly explained. With this new approach, mould designers can easily propagate changes between mould plates or inserts and the cooling system without the need for tedious rework. Hence, this approach can significantly reduce the total design time and the impact of late changes.