Copper and copper alloys are widely used in applications where thermal and electrical conductivity is required. Coppers are used to make cables, wires, tubes, profiles, sheets and plates in aerospace and energy sectors. In addition to its conductivity properties coppers are highly malleable. All-in-all copper is a very popular material. But it is exactly because of its properties that 3D printing with copper has had limited success so far. But recent developments are opening new possibilities for this material in additive manufacturing.
Powder bed fusion is the print technique used to print with copper. The copper comes in the form of powder. Powder bed fusion uses electronic beams to melt the powder so that the material ‘glues’ together. Consolidation happens when the temperature drops. This technique is also commonly known as SLS (Selective Laser Sintering) or SLM (Selective Laser Melting), when working with metals.
SLS is great printing technique for many metals, but for copper this process presented a particular challenge: because of its conductivity properties the heat of the electronic beams was not absorbed but reflected. Another problem that occurred was that when the temperature drops too fast and too low, cracks can appear in the model.
Towards a solution: Green laser and pre heating
Researchers at the Fraunhofer Institute in Aachen (Germany) have been working to address these problems and developed a new technique that should make printing with copper possible. They developed a different type of laser beam, a so called green laser, who’s heat is is better absorbed by the copper, allowing the material to melt more easily.
To avoid cracking of the material when the temperature drops, the material is pre-heated before lasering, thus avoiding temperature drops.
Machine manufacturer TRUMPF has applied these technologies in its new machine, the TruPrint 5000. The machine uses TruPrint Laser Metal Fusion (LMF), a green laser, and preheats to material to 500 °C.
The TruPrint 5000 was demonstrated at the Formnext, 3D print fair in Frankfurt in November 2018. The machine also prints with other precious metals, other then copper.
Heraeus is a German technology group with a focus on precious and special metals, copper among them. Their additive manufacturing division is working on a portfolio of precious metals for 3D printing.
The group developed a highly conductive copper powder with 99.8 percent density of solid copper and conductivity of about 95 percent IACS (International Annealed Copper Standard. Around 85 percent IACS is customary in the market.)
Heraeus presented its highly conductive 3D-printed copper components at At the Formnext 2018.
Copper is a soft, malleable, and ductile metal. Copper is a native metal with a has an orange-red color. It has very high thermal and electrical conductivity.
Applications for copper are:
- electrical wiring (copper is a conductor of heat and electricity,
- building material for roofing, plumbing, decorative elements and sculptures (for ex the Statue of Liberty is made from copper). The copper oxidizes and becomes a light green color.
- constituent of various metal alloys, such as bronze (a copper-tin alloy) and brass (a copper-zinc alloy) and Sterling silver (silver-copper alloy)
- machinery and motors
- marine applications: copper is biostatic, bacteria or other live forms will not grow on it. It was used in shipping to prevent growth on hulls.
- sinks, faucets, doorknobs, handrails etc. Because copper is biostatic it is used (in various alloys) in appliances that are handled by many people, to avoid spreading bacteria.
In summary 3D printing with copper is fast becoming a reality. Technical hurdles are being overcome, and large companies are developing copper alloys in anticipation of market demand.