High-performance electrical steel strip with outstanding magnetizability for large magnets used in medical radiation equipment

Daniel Dunker, responsible for the special product electrical steel strip in Waelzholz’s Material Technology Department, explains: “The electrical steel strip has to generate extremely powerful magnetic fields for this application. Due to the size of the magnets, a large amount of iron is also required. This is why electrical steel strip with a thickness of approximately one millimeter (0.039 inch) is the standard material used to manufacture these special magnets. We supply various versions of it in accordance with the EN 10106 standard.” In addition to its excellent magnetizability, the large material thickness also offers advantages during the subsequent production steps, as it reduces the number of steel plates required for each magnet and therefore the time and effort required for the necessary punching processes.

For magnet-based medical technology applications, Waelzholz offers electrical steel strip with a coating of bonding varnish. Marco Baptista from the Sales Department explains the benefit for the customer: “Large magnets consist of lamination stacks, which in turn are made up of many individual electrical steel strip plates. Thanks to the special varnished surface, customers can efficiently join these plates together into a stable stack via a bonding process. This eliminates the need for additional welding operations.” According to Dunker, in addition to the increased stability of the lamination stacks, joining the plates using bonding varnish has another key advantage for the final application in the state-of-the-art radiation equipment: “This method creates low-vibration stacks that ensure the proton beam is guided reliably and the magnetic field is constantly generated. In addition, magnets whose lamination stacks are connected via bonding varnish operate more quietly, reducing noise pollution and thus stress for the patient. Conventional mechanical connections involving welding or riveting of the steel plates can result in extremely fine gaps, which can lead to vibrations and thus to “frequency hum.”

Coating the electrical steel strip with bonding varnish thus fulfills several requirements simultaneously when it comes to manufacturing large magnets and their subsequent use in medical radiation equipment:

• High stability of the lamination stacks
• Undisturbed magnetic flux for maximum magnetizability by eliminating damaging connections between the steel plates
• Low-vibration stacks for precise beam guidance

For more than ten years, Waelzholz has been supplying electrical steel strip materials used to manufacture high-performance large magnets for radiation therapy. In addition, the magnetic material is suitable for other fields of application in medical technology, such as mechatronic magnet-driven intramedullary rods for bone-preserving leg lengthening procedures.

In this way, we also meet the requirements of the most state-of-the-art technologies for international cutting-edge medicine thanks to the exceptional, customized material properties and precision of our steel strip materials.