The Design of a Magnetic Component for Induction Brazing
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Within the mining industry, jaws are used for drilling in large quantities. Slots are milled in each jaw, into which tungsten-carbide teeth are fitted and brazed. The current brazing process requires heating the whole jaw in a furnace for 4 hours, an inefficient and time consuming process. Induction brazing offers a much faster, cheaper alternative that reduces electricity consumption. Through the development of a concentrated induction coil, consistent uniform brazing can be achieved. For brazing at high production rates a furnace- based technique has disadvantages. These include inconsistency in outcomes, low efficiency and high electricity demand. Induction brazing offers improvements in these respects, particularly if magnetic fields can be focused to give selective heating. However, difficulties may be experienced when brazing metals of dissimilar size and magnetic properties, as magnetic field penetration may be insufficient to give rapid heating of the brazing filler metal. This research proposes a coil design that guides the magnetic field to give penetration at desired locations, despite the presence of materials that could otherwise act as a magnetic shield. Magnetic modelling using the finite element method is presented, considering variations in magnetic diffusivity and skin depth in the approach to Curie temperatures. Comparison to a coil without magnetic field guidance indicates the proposed coil achieves superior performance. This study will add to the scientific knowledge in the field of induction heating, specifically in the area of ensuring that a magnetic field penetrates to a brazing region surrounded on all sides by conductive materials with differing properties.