The effects of toroid winding methods on properties of amorphous ribbon toroids

Amorphous ribbons are principally used in devices as wound toroids. The toroids can be wound in two different ways; i.e. forward wound with the wheel side of the ribbon on the inside of the toroid, or reverse wound with the wheel side of the ribbon on the outside of the toroid. Toroids have been made using these two winding techniques and their magnetic properties (power loss, coercivity, remanence and saturation induction) have been measured under sinusoidal flux conditions at inductions up to 95% of saturation over the frequency range 20 Hz to 20 kHz. Toroids made from two types of material have been investigated; namely Metglas 2605SC type material, Fe81B13.5Si3.5C2, and Vitrovac E6010 type material Co58Fe5Ni10Si11B16. These toroids have also been subjected to annealing at temperatures in the range 325°C to 425°C in air, nitrogen and hydrogen atmospheres with and without an applied field. It has been found that the reverse wound toroids of Metglas 2605SC type material have improved properties compared to the forward wound toroids, with annealing temperature below 365°C. There is no difference in the properties of the reverse and forward wound toroids for the zero magnetostriction Vitrovac E6010 type material. It can be seen that full stress relief does not occur for annealing temperatures below 365°C. The difference in properties of toroids made by the two winding methods are shown and explained by considering the manufacturing stresses, winding stresses and the effects of annealing temperature.