Optimizing HVAC Brazing with Induction Heating: A Journey to Perfection

Application: Brazing 

Industry: Appliances & HVAC 

Application Objectives: A leading HVAC manufacturer is on a mission to combat climate change by boosting productivity with green energy and eliminating open flame torch brazing. Enter UltraFlex Power, providing an energy-efficient and eco-friendly way to harness the power of induction brazing. 

However, the journey wasn’t without challenges. The engineering teams had to: 

• Establish a new brazing process. 
• Prove the feasibility of the U-braze system. 
• Enhance quality and reliability. 

The biggest challenge? Avoid melting the copper tubes, as the brazing alloy has a high melting temperature. They needed to find the fastest heating times without altering the sample geometry (i.e., removing the flanges).  

Equipment: SOLO U-Braze Series with custom coil 

Materials:  

• Copper U-bend Tubes
• Straight tubes
• Plates: magnetic material  

Process:  Optimizing HVAC Brazing with Induction Heating: A Journey to Perfection

The initial brazing tests began with full power for 10 seconds, leading to overheating and excessive alloy flow. Adjustments were made, reducing power to 75%, resulting in longer heating times but still not ideal results. Further fine-tuning brought power back to 85%, shortening the heating time to around 15 seconds, but temperatures remained too high. 

A breakthrough came when small modifications were made to the U-tubes and heat exchanger tubes by adding flares to create a “bed” for the rings. This reduced excessive alloy flow and improved joint quality. The optimized setup, with 75% power and a heating time of 17-18 seconds, produced consistent results without overheating. 

To further enhance consistency, it was noted that robotic automation would eliminate variations caused by manual coil positioning. The customer embraced the idea, and a successful demonstration using a preprogrammed Solo Dragon 24 Series unit showcased flawless results, highlighting the energy efficiency, ecological benefits, and productivity improvements achieved through automation. 

Reference: AR 3464-7285