Microneedle arrays consist of multiple micron-sized features with lengths between 20 to 2500 µm. By puncturing these sharp features into the skin, microscopic pathways are creates which allow the transportation of drug or vaccines to the skin. In a recent work, we demonstrated a methodology to mass produce solid polymer microneedles. The technique utilises a femtosecond laser which ablates microneedle cavities in a metal insert. Afterwards, the cavities are replicated in an injection moulding process to achieve polymer microneedles. Accurate flow simulations would cut down both costs and time for the development of these microneedles, which can vary in size, geometry and polymer, while taking into account different process conditions. In this work, we determine the microneedle replication fidelity using numerical simulations in Moldex3D and compare it to the experimental replication fidelity. The comparison is performed for different sizes of microneedles, different thermoplastics (polypropylene and polycarbonate), and different mould materials (tool steel, copper alloy and aluminium alloy). Accurate injection moulding simulations were achieved by optimizing the heat transfer coefficient, while using a multiscale mesh with a high number of elements.