runnerless mold
A runnerless or hot-runner mould system could be considered as an extension of the moulding machine injection unit. In this case,the polymer is kept molten right up to the cavity gate by means of additional heating elements controlled by thermocouples. The working temperature of the hot-runner system is not dissimilar to that of the molten polymer being processed. In order to maintain a stable running temperature, the hot feed system is either insulated from the rest of the mould,e.g. by an air gap,or controlled by the addition of cooling channels within the immediate vicinity. The choice of method depends on the design of hot feed system adopted. Advantages of the hot-runner mould The principal advantages of employing a hot-runner mould are: (a) reduced cycle times as a result of having a component cooling requirement only. The runner and feed system remain molten above the quickly frozen gate. (b) material savings result from having no sprue or runner systems to granulate or d