Analysis of an as-built metal additively manufactured tool cavity insert performance and advantages for plastic injection moulding

Abstract

Abstract Metal additive manufacturing (MAM) of mould components is associated with cost-intensive post-process finishing operations, which are currently one of the main drawbacks preventing wider industrial adoption of MAM. This work analyses the current possibilities and limitations of MAM for plastic injection moulding tool applications, demonstrating the opportunity to limit post-processes to heat treatment and the machining of the MAM insert outer geometry, which was only intended to ensure the assembly of the insert in the injection moulding frame. The results focused on evaluating the as-built insert cavity geometrical characteristics and the dimensional replication performance of the injection moulding process. The as-built cavity surface texture was comparable to a surface roughness that would be alternatively manufactured by electrical discharge machining (EDM). The cavity texture and features was replicated to the plastic injection moulded samples with an average replication fidelity higher than 95 %, enabling the direct production of inserts with integrated enhanced surface properties and aesthetics. Additional geometrical characteristics, such as global cavity dimensions, corner radii, and the staircase effect of selected features, typical of MAM products, were examined to gather further knowledge of the MAM process resolution and the corresponding replication capabilities of the IM process. Additional considerations with regards to the insert mechanical loading conditions and its durability in terms of the expected fatigue lifetime were addressed, verifying the usability of the MAM insert for production batches of at least 2⋅106 injection moulding cycles. Finally, the improvements in terms of lead-time reduction and production costs associated with MAM compared with conventional tooling technologies were evaluated and discussed, confirming the potential of the presented process chain of MAM for injection moulding tools production.