Brazing
Brazing is a metal-joining process that uses a filler alloy with a melting temperature above 450 °C but below the melting point of the base metals, so the parent parts do not melt. The molten filler is drawn into a tight joint gap by capillary action and solidifies to form a strong metallurgical bond.
In CNC and manufacturing shops, brazing is chosen when a strong, precision joint is required between metals—including dissimilar metals—without melting the parent parts. Typical production methods include torch, furnace, induction, and dip brazing. On the millwork side, a CNC-milled steel engraving can be filled with bronze brazing rod using an oxy-fuel torch, then machined flat in a finishing pass. Tooling relies on brazed carbide assemblies, where carbide inserts are attached to steel shanks and later ground to final geometry. Components are machined to close fit, cleaned, fluxed if required, and heated until filler flows into the interface. Joint clearance and surface cleanliness are critical because brazing depends on wetting and capillary flow rather than mechanical clamping alone. In thermal-manufacturing contexts, controlled atmosphere or vacuum furnace brazing reduces oxidation and improves repeatability on production parts.
Why is brazing useful for CNC-made assemblies?
Brazing allows precise, close-tolerance parts to be joined after machining with less base-metal distortion than fusion welding. This is important for assemblies that must stay dimensionally stable.
What joint condition matters most for a sound braze?
A close-fitting joint with controlled clearance matters most, because brazing relies on capillary action to draw molten filler into the interface. Excess clearance weakens capillary flow and can produce a weak bond.
How is brazing used in tooling manufacture?
Brazed carbide tools use a brazing alloy to attach carbide inserts to a steel shank, after which the assembly is ground to final geometry.