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Fraunhofer IWS project enables green laser to melt pure copper

02 Sep 2020

Previously, it was not possible to melt copper for complex 3D-printed parts using an infrared laser.

Creating intricately-shaped plastic parts with a 3D printer is no longer a challenging process, but an everyday technology. However this scenario is quite different when the material is pure copper: until now, it has not been possible to completely melt this low-melting point metal to create complex components layer by layer using infrared lasers.

But now, the Fraunhofer Institute for Material and Beam Technology (IWS) in Dresden, germany, is now using a novel additive manufacturing system, which processes the metal almost defect-free using a shortwave, green-emitting laser.

This capability, says IWS, enables new production approaches which previously could not be realized with pure copper. Thus, complex components made of pure copper and copper alloys can be realized for aerospace and automotive industry and the efficiency of electric motors and heat exchangers can be increased.

Fraunhofer IWS can now design and create pure copper components with excellent electrical and thermal conductivity. These components enable, for example, more efficient electric motors and innovative heatsinks in power electronics.

Furthermore, applications in coil and inductor production are conceivable. Additively manufactured copper components are particularly suitable for compact devices with small installation space, high efficiency and high performance. For example, more efficient and compact heat sinks for future power electronics can be manufactured as well as particular individual coils for electrical drives in satellites, cooling systems in space propulsion systems and many other parts.

Rare capability

The new laser beam melting system is unique in Saxony – there are only few comparable systems in Germany. Instead of infrared light with a wavelength of 1064 nm, the system utilizes a disk laser with high- energy green light with a wavelength of 515nm.

“Previous experiments have repeatedly shown that infrared laser beam sources of up to 500 watts are not efficient enough to completely melt copper,” commenetd Samira Gruber, who supervises the project as a research assistant at IWS.

Only 30 percent of the energy used reaches the copper material – the rest is reflected by the metal. The new green laser with a maximum of 500 watts offers a different solution: Here, the copper powder absorbs more than 70 percent of the energy used and melts completely, which in turn permits its application in additive manufacturing.

Since copper conducts heat and electricity very well, it constitutes a major improvement if this metal can also be processed in additive production systems. “Components made of pure copper and copper alloys play an important role in aerospace, electronics and automotive industries, for example, in electric drives or as heat exchangers,” said Elena Lopez, head of the additive manufacturing department at Fraunhofer IWS.

“Additively manufactured copper parts are superior to many aluminum solutions due to a higher volume-specific conductivity. This is particularly interesting wherever small designs and high performance are required.”

Many copper parts can already be machined, forged or cast today. However, the implementation of additive manufacturing processes opens up new options to produce highly complex geometries, which are simply not possible with conventional manufacturing.

AM researchers join forces in Saxony

The new Fraunhofer IWS equipment was realized via the “Smart Production and Materials” performance center. This center is an alliance of Technische Universität Chemnitz, Technische Universität Dresden and the Fraunhofer Institutes IWS, ENAS, IWU as well as IKTS, all of which are researching innovative manufacturing technologies and materials for Industry 4.0.

The Trumpf TruPrint1000 laser processing machine equipped with a green laser is now located at the Additive Manufacturing Center Dresden (AMCD). IWS engineers and scientists from TU Dresden collaborate in this center on many further pioneering technologies for additive manufacturing.

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