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This question is one being asked in many brazing shops today, and the answer is a resounding “Yes!” — carbon-fiber reinforced carbon (C/C) fixtures are being used more and more frequently in brazing shops around the world due to their lightweight, high strength, and dimensional stability over a wide temperature range as compared to similar fixtures made from steel.

As shown in Fig. 1, carbon-fibers are long filaments made of carbon, that when blended/woven in a matrix of carbon, creates a reinforced carbon structure that is very strong, lightweight, and has some flexibility. When woven into a carbon-fiber reinforced carbon structure, the material looks like that shown in Fig. 2, where the visible “weave” resulting from reinforcing carbon fibers is clearly evident. When such structures are stacked into a fixture for use in a brazing furnace, it would look similar to that shown in Fig. 3.

In this month's article, we will look further at the placement of TC's in furnace brazing loads, and how, together with correct furnace heating/cooling rates, they can help to maximize uniformity of temperature throughout each brazing load and minimize any distortion of the components being brazed.

To have good control of any furnace-brazing process-run, you will need to know the temperature of the parts being brazed inside the furnace, and in batch-type furnaces this can only be done via well-placed thermocouples (TC's) throughout the furnace and in the load of parts being brazed.

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).

We look now at the fifth of the seven important criteria for good-brazing that are listed in Table 1, namely, the use of fixtures in the brazing process. Fixtures hold the parts being brazed, whether it is a metal vice holding parts for torch brazing, or a large furnace-grate on which parts are set for furnace-brazing, just to name two types of fixtures. The important thing to always remember about fixtures is that they usually 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.

Fixturing. People often do not have a proper understanding of the roll of fixtures in brazing. It can, in fact, have a significant effect on the performance and profitability of any brazing process, be it an operation performed by torch, induction, or furnace. I recently had someone tell me that when they had implemented the fixture-recommendations they learned from my brazing seminar that they had attended, the profitability of that brazing operation went up over 75%. Yes, fixturing is a very important topic that needs to be evaluated thoroughly and properly implemented to optimize your brazing operations.