In 2020, Schunk expanded its expertise to include the composite extrusion modelling process (CEM) by acquiring an ExAM 255 multi-material 3D printing system from German 3D printing specialist AIM3D. The first results of this development partnership can now be seen, as Christian Stertz, project manager for systems engineering at Schunk, explains.

Materials specialist company Schunk is now also a service provider for 3D metal printing. The supplier of series-production solutions for metal powder pressing and injection molding as well as other technologies, has expanded its expertise to include 3D metal printing at its facility in Thale, Germany. This expansion of the metal injection molding process chain in the field of additive manufacturing (AM) makes sense with regard to future bionic construction applications and topology optimization. Component characteristics and cost-effectiveness require different process technologies and manufacturing strategies when it comes to 3D metal printing.

In 2020, Schunk and AIM3D formed a development partnership with three aims:

  • Material developments, such as copper materials and nickel-based materials
  • Further development of plant technology, for example extruder cooling or vacuum clamping table applications
  • Marketing and acquisition for Schunk as a supplier of 3D metal parts with production batch sizes right down to single items.

The focus was 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.

3D metal printing with copper

3D component development in copper is of strategic importance to Schunk, as there are only a few suppliers on the market. The conductive material is required for certain components in the electronics industry. However, the range of industries and applications is wide, 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. The ExAM 255 system from AIM3D featuring CEM technology enables thermal or electrical conductivity advantages to be retained in 3D printing processes. This is a unique selling point, highlighting better and higher conductivity values ​​on the surface and within the components compared to other AM processes. In addition, the CEM process offers material price and resource conservation benefits.

Projects using copper

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 approximately 8.5 g/cm³ with 75-80% conductivity (% IACS). The density values achieved are comparable to metal injection molding (MIM) processes. The density of the copper affects conductivity as well as mechanical properties, such as hardness or wear resistance. There are a lot of 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 mold-based process. However, the following also applies: 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.

Market trends

There is strong AM process potential in a very diverse range of market segments:

  • Transport solutions in aerospace, automotive, rail and shipbuilding
  • parts for drive units
  • interior/exterior components as well as reengineering solutions
  • Medical technology for prostheses and instruments
  • Mechanical and plant engineering
  • Tool-making
  • Sports equipment
  • The construction industry
  • Jeweller
  • Consumer goods.

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.

CEM potential

What makes the AIM3D CEM process so interesting? In general, every AM process offers design and cost benefits compared to conventional manufacturing strategies. Design-wise with the use of bionic geometries and cost-wise in terms of material consumption and tool-free production. The CEM process from AIM3D achieves high densities, high degrees of hardness and high conductivity values for products made of copper. This is unmatched by other AM processes. What’s more, the ExAM 255 from AIM3D featuring CEM system technology is a multi-material printer. So, we can also consider multi-component 3D part applications.

We see a lot of potential for 3D printed copper applications. In the future, copper and copper alloys will play an important role in the MIM and AM business at Schunk for special electronic and thermal requirements. Bearing materials such as bronze or brass are also possible. Here, AM serves as an entry-level technology: AM can deliver prototypes as well as small batches or pre-series production. In addition, this manufacturing strategy reduces the development costs for design optimisations, i.e. redesign or reengineering, as well as producing a variety of versions of copper components.

In principle, there are three groups of applications for 3D printed copper. Firstly, applications with good electrical conductivity in the field of e-mobility, such as electrical contact pickups, e-motors, coils and transformer components. Secondly, applications with good electrical and thermal conductivity in the field of plant engineering, such as in welding and hardening technology, internally cooled inductors in the case of induction hardening of partial structures, such as sprocket teeth, but also specifically shaped welded contacts/sealing jaws with internal cooling. Thirdly, applications with good sliding properties, for example low-volume batches of plain bearings.

With regards to the future market importance of 3D printed copper components – of course, we are talking about a niche market here. For certain applications, bionic structures offer some advantages in the case of reengineering. In future, AM components will not only look different in terms of geometry, they will also perform better functionally, for example in terms of wear resistance. I'm not only thinking about rapid prototyping, but also about the aftersales market. When it comes to spare parts, supply security for small quantities of parts or over very long periods of time can be ensured without the need for expensive tools. In addition, multi-component parts are also possible. Looking ahead, I can see functional and mechanical optimisation of components taking place, since a large variety of alloys will enable numerous new ideas.

Other material groups are also of interest to the Schunk Group. When it comes to AM 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 aluminum and titanium alloys, but all metallic high-performance materials will be of great importance in the future.