ABSTRACT
It is a fact of brazing technology that 90% of all manufacturing problems start life on the drawing board. It is important to realize that many interrelated factors have to be taken into account when designing a joint that is to be manufactured by brazing. The five most important considerations are:
1. The type of parent metals to be joined 2. The position of these parent materials relative to each other in the
joint 3. The type of filler material to be used to make the joint 4. The brazing process to be employed 5. The fixturing of the components
The majority of brazing applications are carried out in air. Unless copper is to be brazed to copper with one of the self-fluxing, phosphorus-containing filler materials, the use of a flux is mandatory. To be successful, a chemically clean surface is provided at the faying surfaces of the joint at brazing temperature so that the filler material will wet and flow into and through it. The fact that a flux needs to be present for brazing operations that are to be carried out in air has a marked effect on the minimum joint gap dimension that can be employed. If too small a joint gap is used it will be impossible for the joint to contain sufficient flux to provide the necessary oxide removal action. As we saw in Chapter 1, for this to occur the mating surfaces of the joint have to be substantially parallel, relatively close together (see Figure 1.5) and chemically clean.
