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Innovation at eldec: Additive Manufacturing Provides Greater Precision in Induction Heating

Traditionally, inductors for induction heaters must be produced using a very sophisticated manufacturing process. Despite the many years of experience and great craftsmanship from those who manufacture these precision tools, there are certain limitations to this manufacturing method. All handcrafted products generally have slight deviations. Even if these can be compensated for without any problem, they still frequently require corrections when it comes time to change the tool. All machine setters are aware of this, even when machining by stock removal. Another limiting factor is the inductor’s size. The smaller and more complex an inductor is, the more elaborate its production becomes— until it can no longer be handcrafted. This was the status quo for a long time until a new manufacturing process involving additive manufacturing was developed, advancing entirely new dimensions of induction heating.

Optimal coolant flow through additive manufacturing of inductors
Additive manufacturing in inductor production
Mounting the inductor winding onto the inductor base
MIND-L 1000 induction hardening machine from EMAG eldec

Dr. Dirk Schlesselmann, Head of R&D for Application Technology at eldec, is eagerly glancing at the laser that is running over the machine’s powder bed. The contour of an inductor winding, produced using the Selective Laser Melting (SLM) process, is slowly taking shape from the powder.

“This is one of the most thrilling innovations to me,” explains Dr. Schlesselmann. “I can switch from design to the production of an inductor winding with just one intermediate step.”

The machine data for additive manufacturing are prepared during this intermediate step—this is known as preprocessing. Optimal surface quality, dimensional accuracy and tool life can only be guaranteed if the winding is correctly aligned within the machine’s installation space.

On average, the production of an inductor winding takes 8 to 16 hours. The tool is manufactured from a copper alloy, and then must be subjected to a heat treatment to establish the material’s optimal electrical conductivity. The winding is then manually soldered to the base of the inductor. “After this step, the inductor can be used and I can run the first tests. This allows me to load the prepared data into the machine on Monday, and by Wednesday I can be testing the first parts in the lab. This is an unbeatable pace,” explains Dr. Schlesselmann.

Additive Manufacturing Enables Perfect Coolant Flow

However, speed is not the only advantage, since the process also opens entirely new possibilities from a design standpoint.

“Optimal inductor cooling is one of the challenges in induction heating. To minimize this temperature rise and the resulting thermal expansion in the tool, a coolant flows through the inductors. This is the only way to guarantee a decent service life. Additive manufacturing now enables us to design inductors in such a way that we are able to guarantee optimal coolant flow,” explains Dr. Schlesselmann. That’s why eldec is relying on the combination of engineering expertise and digital simulation software. The software is used to calculate and analyze the coolant flow. For instance, if there are any “dead spots” in which there is absolutely no coolant flow or if there are any turbulences in the inductor, these areas can be optimized by making targeted adjustments to the topology. This will eliminate hot spots, and a regular and high flow rate can be achieved. The SLM process guarantees that the geometry is implemented as designed and therefore that the inductor also has a perfect cooling capacity.

“This high-precision implementation of the design data is yet another advantage that comes with this process. The dimensional accuracy of the printed and soldered inductor windings is much better than the one produced during the handcrafted production. We use 3D measuring arms to guarantee the required dimensional accuracy. This ensures that each inductor is the highest quality,” argues Dr. Schlesselmann.

A New Process Enables Complex Geometries

In addition to the innovations previously mentioned, Dr. Schlesselmann thinks of a completely different highlight when asked about the advantages of the technology:

“For the first time, we’re not restricted by the limitations in the manufacturing process when designing inductors. We’re now able to manufacture inductor geometries that would not be possible if done by hand. I’m particularly thinking of very small and delicate inductors that open up the use of induction heating for an entirely new range of workpieces. This is where we’re breaking new ground with our customers. And, that’s really thrilling,” explains Dr. Schlesselmann.

The fact that the process works as reliably as described here was already confirmed by eldec in field tests with selected customers. Dr. Schlesselmann reports: “Up until now, we’ve only received positive feedback from our customers. We’re not yet able to make a definitive assessment when it comes to service life, but the results so far show that a significantly longer service life can be achieved with SLM inductors. One customer was able to double tool life with an additively produced inductor without the inductor showing any signs of wear.”

Additive Manufacturing as Part of eldec’s High-Precision Tool System

The new manufacturing process is part of a quality campaign by eldec, aiming to bring induction hardening to a new level.

EMAG eldec calls this bundle of measures high-precision tool system or HPTS and expects it to turn an entire industry upside down.

“It all began with the construction of our new MIND-L 1000 induction hardening machine,” explains Andreas Endmann, Head of Sales for hardening systems at eldec. “The machine stands out because of its very sturdy structure and particularly high precision. We started experimenting with additive manufacturing just around the same time and we quickly realized that we were faced with a unique opportunity to bring induction hardening to an entirely new level of quality. In order to not lose the advantage of a solid machine design and the high precision of the inductors due to imprecise integration of the tools in the machine, we designed an entirely new inductor base as well as a corresponding inductor socket for the machine: the 3D coil connect. This innovation combined with the 3D measurement of printed inductors mentioned above provides for a continuously high-precision induction hardening process, without needing to make expensive adjustments at every tool change. This truly is an enormous advancement,” concludes Andreas Endmann.

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