The main advantages of cold runner systems are the reduction of handling efforts and the savings in material. Lacking knowledge of the operational conditions and the design of cold runner systems prevents the wide industrial application. Especially lacking guidelines for an effective separation of hot and cold sections make it difficult to dimension cold runner systems. The main detail of thermal dimensioning is the separation between the hot plate and the cold die top. This paper shows in which way the shape of the die top and the selection oi the die material affect the temperature distribution at contact.