Laser-powder bed fusion molds without post-processing for micro-injection molding of mini/micro-products

The use of additive manufacturing (AM) processes at the micro-scale helps to increase the development of micro-systems, thus enabling shorter tooling development to be exploited for other micro-technologies, such as micro-injection molding (mu-IM). In recent years, these process combinations have shown their capability of providing greater flexibility to micro-technologies and facilitating a high production rate, in particular allowing mu-IM to be economically feasible for low-volume production. Therefore, in order to assess the feasibility of micro-metal AM for mu-IM mold production, a set of mini- and micro-polymeric parts injected by using molds realized via the laser-powder bed fusion (L-PBF) process is discussed in this paper. The molds were manufactured in low-carbon steel and have been characterized and tested experimentally, without any post-process treatment. Two selected geometries, corresponding to a mini dogbone for tensile tests and a flexural hinge with features at the micro-scale, were designed and realized by the mu-IM process. These were replicated in order to assess the accuracy of the whole process. The obtained results of replication accuracy and mechanical tests confirm that the mu-IM process, performed with an L-PBF-made mold insert, is feasible and affordable for micro-production, although great accuracy, especially in mold design, fabrication, and assembly, is required.