Red Seal Welding Practice Exam

In OFB, how is the filler drawn into the joint?

1. By gravity

2. Using a rod

3. Capillary action

4. Magnetic force

The correct answer is: Capillary action

Capillary action refers to the phenomenon where a liquid, in this case the filler, is drawn into a narrow space or joint by the forces of cohesion and adhesion. In the OFB (Oxygen-Free Continuous Casting) process, the filler is drawn into the joint between two copper plates through capillary action. This is due to the narrow gap between the plates, which enhances the capillary forces, and the surface tension of the molten filler. Options A, B, and D are incorrect as gravity, a rod, and magnetic force would not be able to draw the filler into the joint in the same way that capillary action does.