The Brazing process is a joining process that uses a filler metal to bond two or more metal components together. It involves heating the metal parts to a temperature below their melting point and melting the filler metal, which then flows between the joint surfaces by capillary action. As the joint cools, the filler metal solidifies, creating a strong and permanent bond.
The Brazing Process Steps
Here is a general overview of the brazing process:
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Selection of materials:
Choose the appropriate base metals and filler metal for the brazing operation. The base metals should have compatible melting points and also metallurgical properties, while the filler metal should have a lower melting point than the base metals.
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Surface preparation:
Thoroughly clean the surfaces to be joined. Remove any dirt, oxides, oils, or other contaminants that could interfere with the brazing process. Surface preparation methods may include degreasing, chemical cleaning, wire brushing, or abrasive cleaning.
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Assembly:
Position the metal parts in the desired configuration for brazing. Use fixtures, clamps, or jigs to hold the parts securely in place during the heating and cooling process.
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Flux application:
Apply a flux material to the joint area. The flux serves multiple purposes: it removes oxides from the metal surfaces, promotes wetting and flow of the filler metal, and prevents the formation of new oxides during heating. Common types of flux include borax, boric acid, and flux pastes.
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Heating:
Heat the assembly to the appropriate brazing temperature. The specific temperature depends on the base metals and filler metal being used. Heating methods can include torch brazing, furnace brazing, induction heating, or resistance heating. The heat source should be controlled to ensure uniform heating and prevent overheating or distortion of the components.
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Filler metal application:
Once the base metals reach the appropriate temperature, introduce the filler metal into the joint. The filler metal can be in the form of wire, rod, foil, or preforms. It is placed near the joint and allowed to melt and flow into the gap between the parts through capillary action.
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Capillary action and solidification:
As the filler metal melts, it is drawn into the joint by capillary action. The capillary forces depend on the joint clearance and the surface tension of the molten filler metal. The filler metal wets the base metal surfaces and forms a metallurgical bond. Allow the joint to cool naturally, allowing the filler metal to solidify and form a strong, durable bond.
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Post-braze treatment:
After brazing, remove any remaining flux residues and clean the joint. This can be done through mechanical or chemical methods, depending on the flux used. Inspect the brazed joint for quality and integrity.
It’s important to note that brazing can be performed with different types of base metals and filler metals, each with specific temperature requirements and considerations. The process parameters may vary depending on the application and the specific materials being joined. Finally, contact Custom Creek today for all your fabrication needs!