Thermal conductivity augmentation of epoxy injection moulds for cooling time reduction

Polymer injection moulds are generally manufactured with tool steels which give reliable functioning of moulds with long service life. Manufacturing of injection moulds in steel is a lengthy process due to the strength and hardness. If the injection mould is required quickly for a short prototype or production run, one of the good choices is to use Aluminum filled epoxy material, which can give a mould in a very short time using Rapid Tooling (RT) techniques, as compared to a machined tool. Aluminum-filled epoxy tools work best for relatively simple shapes. The benefits of fabricating injection moulds with epoxy resins includes time saving, ability to set at room temperature and ease of machining. But a major drawback of epoxy material is that the cooling time for epoxy injection moulds are still relatively long due to the poor thermal conductivity of epoxy. This paper reports investigation of an innovative idea for enhancing the thermal conductivity for epoxy moulds. The basic concept behind the idea was to embed high thermal conductive metal insert within the mould between the cavity and the cooling channel. This technique will increase the effective thermal conductivity of the epoxy mould, leading to reduction in cooling time for the injection moulded polymer part. By substituting part of the epoxy with low-cost aluminum, a cost advantage is also to be derived, besides increased mould strength. Experimental analysis done in the current study also verified that mould with embedded metal insert has considerable shorter cooling time. © Copyright 2014 by Research Publishing Services.