Fig. 1 Heavy basket used to hold light-weight parts. (Dan Kay photo)
In this month’s article, we continue to look at methods you can use to keep fixturing-weight down to a minimum, especially in furnace brazing, remembering once again that fixtures (baskets, frames, grates, dead weights, etc.) represent a large mass of metal (the material most often used in fixturing) that absorbs a lot of heat and can thus significantly increase the brazing time needed to complete a braze. Make it your job to significantly reduce the amount of fixturing-weight put into your brazing furnace.
In last month’s article, I mentioned that someone increased the productivity of their brazing operations by over 75% when they implemented the fixturing recommendations I made to them during the brazing-seminar they attended (the same recommendations I’m making in this article).
The heavy basket shown in Fig. 1 was used to hold some very light parts for furnace-brazing. The parts, which, as a group, only weighed a few pounds, required the use of a fork-lift truck because of the heavy weight of the basket used to hold them. The basket was too heavy to be lifted and carried by two men without significant risk of back injury. Why did they use this heavy basket? I was told it was the standard basket they used in their furnace for all their brazing, irrespective of the weight or size of the parts being brazed. These people were NOT taking into consideration the large amount of heat energy needed to heat the basket, which was significantly greater than the heat needed to braze the light-weight parts. Note, too, that those light-weight parts were hollow tubes onto which they wanted to braze a series of thin laminations.