To a great extent, metalcasting is problem solving, and as metalcasting technology advances the problems that are solved grow more complex – overcoming the limits of time, space, and cost. The emergence of 3D printing as an effective production-scale process is expanding foundries’ potential to address customers’ needs, solving problems in new ways. 

Producing sand molds and cores is the most notable recent development in foundries’ incorporation of 3D printing, and much of that is that has been the work of Voxeljet Technology GmbH. It supplies industrial-scale 3D printing systems and operates one of Europe’s largest service centers producing metalcasting molds and cores on demand.

Recently, one of Voxeljet’s customers, the Schmolz + Bickenbach Guss Gruppe, ordered a VX1000 large-format, 3D printer (with a build space of 1,060x600x500 mm), and will introduce the process for mold production at one of its specialty steel foundries.

The problem-solving dimension of 3D printing in mold production emerged recently in a project involving Wolfensberger AG, a steel foundry in Switzerland, and Turbal AG, a manufacturer of turbine systems, and a small hospital in Ethiopia where a defective Francis wheel for a critical water turbine was impeding the availability of electricity.

The effort to produce a new wheel for the Ethiopian clinic was led by Turbal, a family-owned company in Switzerland. Solving the clinic’s problem was made difficult because conventional production of turbine wheels is highly detailed, labor-intensive, and expensive process because it requires manual production of several sand core segments and complicated undercuts. Voxeljet's 3D printing technology offered a well-designed, fast, and cost-effective alternative.

"Once we heard about the problem, we immediately decided to help,” explained Dr. Ingo Ederer, CEO of Voxeljet Technology GmbH. “Our 3D print technology is virtually predestined for cases such as these. The state-of-the-art printing equipment at our service center allows for economical and tool-less production of high-quality sand molds and cores for metalcasting based on CAD data, even for a batch size of one. Producing a sand core for the wheel is a routine undertaking for us.”

Once the necessary CAD data for the wheel was available, Voxeljet started the process of producing the flow-carrying interior for the Francis wheel. In this step, forming the monoblock sand core is a fully automated process using 3D printing. It replaces several sequential, manual processes for producing core segments. In contrast to standard mold manufacturing, for which producing model plates or core boxes may can take several weeks, 3D printing makes it possible to print smaller sand molds in as little as a few hours.