Note: Brazing copper tubes to a brass manifold block
Objective:
Heating a brass block and two copper tubes to 1400 °F (760 °C)
End Product:
Brass block
Equipment:
Ambrell 2.4 kW, 150-400 kHz solid state induction heating system equipped with a remote heat station containing two 0.66 μF capacitors (total 1.32 μF) A multi-turn helical coil
Materials:
Brass block (diameters of .25 in /6.35mm and .375 in /9.5mm) Copper tubes Braze pre-forms Flux
Temperature:
1400 °F (760 °C)
Frequency:
106 kHz
Testing:
The copper tubes and brass block were fluxed, assembled, and placed into the induction coil. There were two assemblies. The .375 in /9.5mm copper block assembly had more mass and required 90 seconds to bring it to temperature. The .25 in /6.35mm copper block assembly was heated to temperature within 60 seconds. Faster cycle times were tried in both cases, but localized melting occurred.
Benefits:
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Speed: The proposed process met the client"s time objective, and is faster than oven heating
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Part quality: The client was suffering from part quality issues and rejects while using an oven; induction offers a good quality braze joint
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Floor space: Induction uses less floor space than an oven
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Energy efficiency: Ovens take time to warm up and use more energy than induction, which has instant on/off

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