by Benjamin Delignon, Head of Innovation at AMEXCI
In the last two years, more and more additive manufacturing technologies claimed to print copper. At first sight, it is now possible to produce small to large components, even with high accuracy. Does copper printing already reached its mature age?
Copper printing – for what applications?
Traditionally, Copper alloys are used in the industry for applications where heat or electrical conductivity plays a major role, such as heat exchangers or coils – often with complex shapes to optimise their function, leading to rather expensive manufacturing methods.
Thermal and Electric conductivities highly depend on the material produced (e.g., alloy composition, density, thermal history), but these functions can also be enhanced through the design of the component: that is where Additive Manufacturing plays a major role. Complex structures and shapes can now be manufactured, and at a relatively low cost compared to the function improvement they provide.
AM technologies producing copper applications
Several AM techniques are currently available to produce pure Copper* components. Laser Powder Bed Fusion (with Green or Blue lasers, or high power infrared lasers) is struggling with the low heat absorptivity of the laser, which complexifies the production parameters definition – but promising results are already available from companies like Trumpf, EOS and more recently Reinshaw. Furthermore, a potential solution might lay in the powder: the Swedish company Graphmatec is currently studying the effect of graphene addition, with highly promising results.
What about Electron Beam Melting? Using no lasers, it is not facing the same challenges as LPBF, but has its own – such as a limited process window and the removal of the sintered powder surrounding the part. However, some products are already on the market, for instance inductor coils, manufactured by Spanish company 3D Inductors. For larger components where productivity is the key word, cold spray companies such as Spee3D are pushing the limits and getting more interest, as shown by their increasing number of machines set up.
On the other side, for small parts, Metal FDM and Metal Binder Jetting are showing great promises for high-accuracy components. Digital Metal just announced the addition of copper to their material portfolio, and Markforged Metal X machines have already been set up all around the globe.
Machine and feedstock are available – but are they industrial solutions?
As part of one of our Multi Owner projects, we investigated the material properties of various AM technologies, with diverse results. In this project, the Metal FDM samples were produced by Marcel Escursell, AM expert at SKF, in their Göteborg facility. He accepted to share his feedback on their machine, and especially on Copper printing:
What type of applications lead to this investment, and why this Metal X machine in particular?
Mostly tooling, we chose MetalX since we already had good experience with MarkForged composite printers. We’re mainly targeting tooling, sometimes we print non-functional prototypes but not so often.
When did you set up the machine and how easy was it to learn how to use it?
We installed the printer in 2019 and it was fairly easy to learn how to use it. However, it’s considerably more complex to handle than a polymer or composite printer since there are 3 steps involved: printing, de-binding and sintering. The machine set up took 2-3 days and training only half a day. Knowing that the software is the same as for Markforged composite printing (Eiger), our previous experience helped.
Are you globally satisfied with the machine?
We succeed to print the components we planned for, but we were surprised by the total leadtime (printing, de-binding, sintering took 1 to 2 weeks in total) and the printer speed, which is significantly slower than those for MarkForged composite printers. The maintenance costs are also higher than for composite printing.
What machine evolution are you expecting?
Like other Metal FDM suppliers, a great step to shorten the leadtimes would be to skip the de-binding (washing) step. When printing solid parts the de-binding takes several weeks, which is too long for our needs. Printing larger parts would also be a great addition, but I guess the sintering step remains a challenge.
For the moment we haven’t confirmed the maximum potential for the MetalX. The main limitations are the cost and time as well as the component size. Knowing we don´t have a CNC machine in our department, as soon as a machining operation is needed, then using the MetalX is not relevant due to the high total leadtimes. For other components, using the Metal X is often a valuable option.
As for any AM challenge, one of the first question should be: what for? Why print in Copper? The component function, size, and accuracy required, will already filter the list of AM materials and technologies compatible with your need. Following these first technical considerations (“is it feasible?”), comes the economic question. Compare to conventional solutions, AM is also often more expensive – especially true for Copper printing which requires expensive feedstocks. Its high cost has to be compensated with high value add(s), such as a great function improvement (exceptional increase in thermal or electric conductivity through material properties and redesign), additional advantages in the supplychain (e.g, low MOQ, shorter leadtimes) and other improvements specific to your application and company – for instance reducing the carbon footprint of your component. As always in AM, a look at the big picture is needed to see the global impact of this Copper printing solution.
Nonetheless, the technologies might not match your requirements (yet), but numerous projects are trying to solve this challenge, to finally have a reliable, accurate and mature solution – industrial, in a sense.
* In this article, we only consider all the materials marketed as “pure copper” – e.g. not the CuCrZr alloy, well established in the AM Space industry.