A 3D printed copper alloy for energy-efficient induction coils
When we look at the future of induction hardening, our team at GKN Additive knows that additive manufacturing will play an important role, especially in the design and production of more efficient copper induction coils.
Fortunately, we do not have to look too far into the future to see the benefits of 3D-printed copper coils: production is already possible using a specialized copper alloy. GKN Additive’s CuCr1Zr alloy offers users the benefits of copper, like strength and conductivity, without the challenges associated with traditional production.
Comparing conventional and 3D-printed copper induction coils
Pure copper, though sought after for its high conductivity, has presented challenges to the additive manufacturing industry. Because of its high reflectivity, the material is not suitable for use with powder bed systems that rely on infrared laser technology. We have created a copper alloy that offers the best of pure copper: High conductivity and perfect 3D printability. The ideal combination lies with adding certain metal alloys to pure copper, like chromium and zirconium, and adjusting the melting and heat treatment process.
EDX analysis of CuCr1Zr (left) compared with pure copper (right)
Looking at the mechanical properties of our copper alloy for additive manufacturing, the material’s strength is superior to pure copper. To simplify production, manufacturing companies can integrate-3D printed coils into their existing processes since the material can easily be soldered with the same equipment and material used for conventional copper.
Overview of the mechanical properties of CuCr1Zr
In terms of conductivity, arguably the most important characteristic of copper, comparing CuCr1Zr and pure copper could be an initial concern to skeptics. Looking at the printed raw material, our copper alloy has 23 percent of the electrical conductivity of pure copper. However, after the 3D printing process is complete, parts printed from the alloy have to undergo thermal processing to achieve much higher conductivity rates. At the end of the process, a heat-treated, 3D-printed part made from CuCr1Zr has 90 percent of the electrical conductivity of pure copper.
The electrical conductivity of heat treated CuCr1Zr is about 90% compared to the electrical conductivity of pure copper.
🔈 Are you interested to learn more about the hardening results of additively vs. traditionally soldered inductors? Then head over to Galina's latest blog post right here!
CuCr1Zr alloy unlocks the power of additively manufactured copper induction coils
To envision this copper alloy for additive manufacturing, it is vital to consider how the geometry and design freedom created by Powder Bed Laser Fusion (PBLF) elevate the material’s characteristics. In other words, 3D-printed induction coils made using our copper alloy powder have superiority potential against more traditional pure copper coils - soldered or bended - in terms of performance, durability, efficiency and cost.
A recent induction hardening simulation where we compared one of our 3D printed copper coils to a conventional bended copper coil showcases the many ways that 3D printing an induction coil achieves better results.
In the experiment, we maintained the same boundary conditions, magnetic excitation and frequency of simulation for both induction coil versions. As shown below, the main difference between the coils at first glance is displaying the conventional copper coil’s rounded tube structure and the 3D-printed coil’s square geometry.
The 3D-printed coil’s new generated geometry allowed us to improve a number of performance factors. For one, by integrating a hollow, square-shaped coil, we were able to achieve a larger cooling area to increase the coil’s lifetime and reduce its energy consumption. While the conventionally-bended coil requires a current value of 1,454A, the 3D-printed coil only requires 1,333A.
In this sample, the magnetic field created with excitation of the AM-coil, is more penetrating than the one created by the conventional coil. The thickness of the AM coils' hardening layer is higher than the hardening layer of the conventional coil. (Boundary conditions and load: f=100kHz, same magnetic excitation)
Further, the simulation demonstrated that the magnetic excitation field of the 3D-printed copper coil penetrates deeper than in the conventional coil. This deeper magnetic excitation means that the thickness of the hardening layer also increases.
If you were to 3D print an exact replica of a traditional bended copper coil, it is likely that the coil’s properties and performance would not be up to standard of the conventional coil. By leveraging the benefits inherent in the additive manufacturing process, like design freedom, it is possible to produce induction coils that are superior in every way.
We’ve also conducted similar simulations comparing 3D-printed induction coils to soldered coils and have found similar results. Across the board, 3D-printed coils made from our copper alloy perform more efficiently than conventional ones due to advanced design techniques.
Higher repeatability and longevity for your coils
Questions surrounding the tolerance and repeatability of our 3D-printed copper alloy are inevitable. And for manufacturers accustomed to working with pure copper, these questions are warranted. Proven through advanced testing, this copper alloy can achieve tolerances in accordance with ISO 2768 class mK and has a surface roughness of Rz<40μm.
The magnetic field of the Inductor has fit perfectly to the component.
Repeatability also often comes up in questions, our clients ask us, to assure that ordering a 3D-printed coil today will be the same as if they order another one in two months. Due to a combination of technical reliability and our ADDvantage production software, repeatable results for 3D-printed copper coils are never a concern at GKN Additive. Compared to bending or soldering, 3D-printed copper coils have demonstrated a much higher degree of repeatability.
Extensive R&D work has shown that induction coils 3D printed from our copper alloy are more durable than conventional pure copper coils. Compared to soldered coils, our printed coils demonstrate a 3-4 times greater durability. 3D-printed coils are minimum twice as durable as bended coils because the wall thickness is consistent throughout the structure, whereas bended coils shows weaknesses and thinner walls where they have been bent.
GKN Additive’s 3D printed copper induction coils present a range of benefits compared to conventional pure copper coils, thanks to a combination of GKN Additive’s innovative CuCr1Zr alloy and extensive manufacturing experience and the design freedom of additive manufacturing. Those interested in ordering a 3D-printed copper induction coil from GKN can expect rapid delivery times (within 10-15 days) and in-depth support from our skilled product engineering team, including the design of an induction coil 3D model (within 5 additional days).
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