Batch size is the most important criterion in the trade-off between metal injection molding and 3D metal printing. That is the conclusion of the German supplier Schunk Group, which has both techniques in house. 3D printing is interesting for less than 100 parts. This makes 3D printing interesting for the manufacture of, for example, copper coils for induction hardening of parts. Because the properties are at the same level as copper MIM parts.
The Schunk Sinter Metal business, which is part of the group that has 9,000 employees worldwide, has more than 90 years of experience in processing metal powder into high-quality end products. It uses, among other things, Metal Injection Molding for this. This business unit has invested in AIM3D’s CEM technology.
Low volume production of copper inductors ideal application for printing technology from AIM3D
No filament but pellets
CEM stands for Composite Extrusion Modeling. In this process, MIM powder is processed into raw material for the 3D printer, but this time not in the form of filament, but pellets. This makes it easier to 3D print. Binding takes place both chemically and thermally, and the last step is sintering. Two years ago, the supplier already bought the ExAM 225 multimedia material 3D printer from AIM3D, and the two companies started working together. This has taken place in material development (including copper), further development of printing technology (including cooling of the extruder and clamping with vacuum) as well as marketing and procurement.
Copper parts for e-mobility
One of the concrete results of this collaboration is 3D printing with copper, a material that is gaining interest as e-mobility grows. Schunk has developed inductors for induction hardening of automotive gears and sprockets on chainsaws. These parts undergo, among other things, induction hardening for the highest mechanical requirements. The physical properties of these copper components are a density of about 8.5 g / cm³ (rel. About 95-96%) with a conductivity of 75-80% (% IACS). The obtained density values are comparable to MIMs. In particular, the density of copper affects the conductivity, but also the mechanical properties, such as hardness or abrasion resistance.
The benefits of 3D printing
Christian Stertz, System Engineering project manager at Schunk, finds the benefits of additive manufacturing in design freedom, such as internal cooling ducts or undercuts. In addition, you can 3D-print bionic structures that save weight and material while increasing functionality. The technology also contributes to cost reductions because the cost of machining and tools is lower because it is not a mold-based process. However, the following also applies: the CEM process is usually not suitable for very simple geometries and for large batches, as established series production processes such as MIM are more economical in these cases. And it is precisely at this last point that 3D printing and MIM meet in his eyes.
Prototyping and low volume production
Schunk focuses on fast prototyping and low-volume production, where batches are too small for conventional sintering technology. 3D printing can therefore be an excellent supplement here. Christian Stertz sees applications in several markets: In addition to the automotive industry, it is the pharmaceutical industry, general machine construction, the tool industry, the construction industry, jewelry production and consumer products. “As customer demand develops for new design and material options, such as bionic design, the range of 3D printing technologies will also continue to evolve. Certain applications prefer processing with certain AM methods. There will also be niches.”
3D printing of several materials
The Schunk project manager sees a major role for both MIM and additive manufacturing in the future, especially for copper elements for electronics and thermal applications. He also sees opportunities for the aftermarket, the spare parts business. Schunk is also very interested in the fact that AIM3D’s CEM technology is suitable for printing several materials at once. “In the future, I see functional and mechanical optimization of parts taking place, as a wide range of alloys will enable many new ideas.” As for additive manufacturing, the group is, according to him, only in the beginning. There is also still a great deal of development potential in mechanical and plant technology. At Schunk, of course, we do not only 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. At present, our focus is less on aluminum and titanium alloys, but all high-performance metallic materials will be of great importance in the future. “