The materials specialist company, Schunk – through its partnership with AIM3D – looks to grow as a service provider for metal 3D printing with a particular focus on copper. As a supplier of series-production solutions for metal powder pressing and injection molding, as well as other technologies, Schunk has been expanding its service offering to include metal 3D printing capabilities at its facility in Thale, Germany. In 2020, the company acquired an ExAM 255 multi-material 3D printing system from German startup AIM3D. Based on the proprietary composite extrusion modeling process (CEM), the AIM3D systems are able to produce green parts by extrusion of bound metal thermoplastic pellet feedstock materials. These can be subsequently sintered in a furnace as if they were produced via metal injection molding processes.
The first results of this development partnership can now be seen, as Christian Stertz, project manager for systems engineering at Schunk, explained.
For Schunk, the expansion of the metal injection molding process chain into the field of additive manufacturing makes sense with regard to future bionic construction applications and topology optimization. The aim of the cooperation between Schunk and AIM3D covers three strategic approaches. Namely, material developments (such as copper materials and nickel-based materials), further development of plant technology (for example extruder cooling or vacuum clamping table applications), and marketing and acquisition for Schunk, as a supplier of 3D metal parts with production batch sizes right down to single items.
The focus is on rapid prototyping and low-volume production, where batches are too small for conventional sintering technology. The creation of copper components using 3D printing is one such development project.
Additively manufactured component development in copper is of strategic importance to Schunk, as there are only a few suppliers currently on the market. This conductive material is required for several components in the electronics industry, however, the range of industries and applications is much wider, including applications focusing on thermal management, primarily in mechanical and plant engineering. There are also applications with an emphasis on low-loss energy transmission, such as e-mobility, welding and hardening technology, as well as in the field of energy supply. Pure copper as well as copper alloys are utilised in these applications.
“When it comes to additive manufacturing strategies we really are just at the beginning. There is still great development potential in machine and plant technology, too. Of course, at Schunk we don’t just see potential in copper-based materials. Low and high-alloy steels or nickel-based materials such as Inconel or Hastelloy-X also play a role, as do cobalt-based materials. Currently, our focus is less on aluminium and titanium alloys, but all metallic high-performance materials will be of great importance in the future”, said Stertz.
According to Stertz, the ExAM 255 system from AIM3D, featuring CEM technology, enables thermal or electrical conductivity advantages to be retained in 3D printing processes. He sees this as a unique selling point, highlighting better and higher conductivity values on the surface and within the components compared to other additive manufacturing processes. In addition, the CEM process offers material price and resource conservation benefits.
For example, Schunk has developed induction hardeners (inductors) for gear wheels in the automotive sector and for chain wheels on chainsaws. This involves induction hardening of a component through partial surface hardening for the highest mechanical requirements. The physical properties of these copper components are a density of approx. 8.5 g/cm³ (rel. approx. 95-96%) with 75-80% conductivity (% IACS). The density values achieved are comparable to metal injection moulding (MIM) processes. The density of the copper, in particular, affects conductivity as well as mechanical properties, such as hardness or wear resistance.
Stertz emphasised the benefits of this AM process compared to conventional manufacturing strategies. The high degree of geometric freedom allows for internal channels or undercuts. In addition, bionic structures that save weight and material while increasing functionality also enable cost savings. As is the case with any AM process, using CEM systems from AIM3D results in savings on machining and tooling costs as it is not a mould-based process. However, the CEM process tends not to be suitable for very simple geometries and for large batches, since well-established series-production processes such as MIM are more advantageous in these cases.
“With the further development of customer demands regarding new design and material options, such as bionic design, the range of 3D printing technologies will also continue to evolve. Certain applications favour processing with certain AM methods. Niches will also emerge and competition that squeezes out niches using established processes will continue to drive technology development forwards”, said Stertz.