Optimisation of the Injection Moulding Process for Thick-Walled Parts Using Conformal Cooling Channels and CuBe Alloy Inserts

The injection moulding of thick-walled parts presents significant challenges, particularly during the cooling phase. Alternative mould strategies, such as conformal cooling channels (CCC) or the use of high-thermal-conductivity materials, can enhance heat transfer and reduce cycle times. This study investigated the injection process using 316 L stainless steel moulds with conventional cooling and CCC, comparing their performance with a copper–beryllium (CuBe) mould, which exhibits approximately ten times higher thermal conductivity. CAE simulations revealed a significant reduction in cavity temperature when CuBe mould was used, as well as increased temperature homogeneity with CCC, even at a coolant flow rate 3.5× lower due to manufacturing constraints. Injection process monitoring showed cycle time reductions of 18% for the CuBe mould and 11% for the CCC mould compared with the conventional 316 L cavity, alongside proportional improvements in part weight and dimensional accuracy. Furthermore, the improved temperature homogeneity achieved with CCC improved the mechanical strength of the parts by 17%, while the higher thermal conductivity of the CuBe mould increased crystallinity and frozen-layer thickness, reducing mechanical properties by 13%. Nevertheless, all parts met the minimum requirements for high-pressure applications, demonstrating that gains in process efficiency did not compromise product performance. The financial assessment showed that, despite higher manufacturing costs, productivity gains made the CuBe mould the most economically favourable option, whereas the CCC mould, although delivering superior mechanical properties, was less cost-effective due to higher manufacturing costs and lower thermal efficiency, even when lattice structure optimisation was applied to reduce costs associated with PBF-LB manufacturing processes.