Reports of failures to effect repairs are usually of the forms:
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“I cannot get the rods to melt by rubbing it on the metal”
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“The rod melts when I rub it on the hot metal, but does not stick when cool”
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“I just ended up with a big blob of metal”
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The first problem is due to using too small a torch. All torches have a high enough flame temperature, but more important is the total amount of heat the torch can produce. It must be able to heat the work faster than the metal can dissipate the heat. Apart from larger torches, using insulated bricks to form a brazing hearth can help by minimising heat loss from the work.
There are three reasons for the second problem:
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The user is trying to braze an unsuitable metal e.g. Steel.
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The user is trying to braze copper, but has not heated it sufficiently -
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The user is repairing aluminium, but has melted the rod with the flame.
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The final problem is usually due to a low melting point alloy. This is often a magnesium alloy. Although magnesium melts at a similar temperature to aluminium, some of its alloys melt at very low temperatures close to the melting point of HTS-