An investigation into the fast thermal cycling of injection mould tools to extend the flow length of filled and un-filled polymer compounds at thin sections (～0.5mm) with standard equipment at reduced pressures

摘要

The traditional approach to manufacturing parts with very thin sections (～0.5mm) is to use extremely high injection pressures and speeds, with often the use of additional accumulators fitted to the injection moulding machines. This allows material to be injected quickly before it chills and solidifies inside the mould tool. As a consequence moulds tools have multiple gates, need to be strong/robust so are often of high mass with very thick faces which are intransient to thermal change. Today a part is probably designed with a thicker section and a low level of reinforcement to meet specification, increasing weight and cost. This is because material's with high reinforcement levels (>30%) are difficult to mould, more so with long fibre lengths (>10mm). If this could be changed designers would have greater freedoms and could make thin, lightweight parts with high levels of reinforcement. The main aim was to use active thermal cycling of the mould tool to achieve longer polymer low lengths in injection mouldings at section thicknesses of 0.5mm with reduced injection and clamp force pressures. This paper describes the practical research undertaken using active thermal control of the mould tool to manufacture thin section mouldings at high gloss levels with unreinforced and reinforced polymers.