Things to Consider
Type of metal
The power and heating rate required will be determined by the type of metal of the work piece. High resistivity metals strongly resist the current flow that is required in induction brazing and heat builds up quickly in these metals. Steel and iron will heat faster than low resistivity metals such as aluminum, copper, and brass, which require more power.
Size of the metal
The size of the piece determines the induction heating system’s operating frequency. Brazing smaller parts requires higher frequency (>50 kHz), while larger parts require lower frequency (>10 kHz) to achieve more heat penetration. You should also consider the thickness of the metals to be brazed. With conductive materials, about 85% of the heating effect occurs on the surface, meaning thinner pieces typically heat faster than thicker pieces. Therefore, larger or thicker parts will take longer to reach the brazing temperature compared to smaller or thinner parts.
In addition to the heat induced by eddy currents in induction brazing, magnetic materials also produce heat through what is referred to as the hysteresis effect. Because of this effect, magnetic materials heat faster than non-magnetic ones.
The design of the coil used in induction brazing is crucial to ensure even heating of the brazed components.The coil should be individually designed for each braze joint in order to maximize the efficiency; coils may be as simple as a single round section to much more complex shapes. The closer in proximate the coil is to joint the more efficient the brazing process will be.