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AC/OX CUTTING/WELDING/BRAZING Edge preparation

Capillary brazing

Capillary brazing requires a filler material, which melts to a thin flowing liquid with excellent wetting properties, and a joint with parallel surfaces. The opening between the surfaces should preferably be 0,05 - 0,1 mm to obtain sufficient strength and capillary effect. This effect is based on the surface tension of the liquid filler metal, which will pull the filler in between the surfaces.

Joint types

Where possible the surfaces should overlap 3–5 times the wall thickness of the thinner part.

Heating should be done with a neutral or slightly reducing flame, which will give assistance to the flux in removing oxides from the surface. Heat the entire area of the joint uniformly. Starting with the thicker

part to ensure that both surfaces

reach correct temperature quickly and simultaneously, within max. 2-3 minutes to avoid damaging the flux. Do not heat directly on the filler material. When the joint has reached correct temperature the end of the brazing rod should be touched to the joint, and the heat from the workpiece will melt off filler material.

Maximum capillary gap between joint Surface 0.1 mm.

Coat joint surface with flux

Allow sufficient time for the capillary action to take full effect. With proper joints this will happen very quickly. Keep the workpiece in position until it has cooled off and the filler has solidified. The workpiece can then be released, and if the material allows, cooled off in water.

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Flux residues should be removed to avoid corrosion.

Heat evenly