UltraFlex Induction Heaters Solder Brass Tube within 25 Seconds

[July 20th, 2018] Several tests performed by UltraFlex Power Technologies showed that brass tubes can be soldered to galvanized steel pans within less than 0.5 minutes. It took only three tests to optimize the soldering results, identifying the best flux and induction heating process to be used.

All three tests had been performed using brass tube 67.31” (0.66mm) high and 0.037” (0.93mm) thick, with 1.5” (38.1mm) outside diameter. The tube had to be soldered to a 0.026” (0.66mm) thick galvanized steel plate using AlphaFry 0.125” (3.17mm) diameter lead free solid wire and soldering flux. Three types of soldering flux had been used in the testing, to identify the one performing best in this induction heating application: 95 Tin, 5 antimony AlphaFry soldering paste flux, 95 Tin, 5 antimony Rectorseal, Nokorode regular paste flux and 95 Tin, 5 antimony Harris Bridgit lead free burn resistant soldering paste flux.

The induction heating was done using a 5 kW Induction Heating system from the UltraFlex UltraHeat SM series. This is a compact induction heating system, easy to tune to a wide range of loads and coils and capable of delivering full power in the 30kHz – 200kHz frequency range. In this case, power of 2.5 to 2.9 kW had been used to reach a target soldering temperature of 420°F (215°C).

In the first test case, where 95 Tin, 5 antimony AlphaFry soldering paste flux was used, the surface coating was first removed using sand blaster. During the induction heating, adjustments of the tube position in the coil were applied to prevent melting of the top of the tube. Power was also turned on and off to avoid overheating of the tube.

The first test case showed that the flux used was too flammable. The solder flow was, in addition, a bit uneven, favoring one side. This was also due to the fact that the part had been heated before. It took up to 25 seconds for the entire solder cycle.

In the second test case the soldering set up was optimized by skipping the sand blasting of the surface and heating the part plus applying some alloy at the solder joint beforehand. The induction coil was positioned at the center of the brass tube and the induction heating continued for 15 seconds without overheating the part. This test resulted in improved spread of allow around the part and good solder joint, even though one piece of the alloy did not entirely melt.

In the third test the steel pans had an additional pan inside, to help keep the brass tube in the correct location. A new part, not exposed to any heat, alloy or flux had been used.

The additional pan added extra mass to the part and created an additional heat sink. Overheating of the tube was possible in this case, so power was turned on and off.

This third case showed the best solder results, with solder flow evenly flowing around the tube.

In all three tests, temperature controller and temperature monitoring system had been used to eliminate the possibility of overheating and damaging the parts. UltraFlex engineers confirmed that if a lower, 2 kW induction heating unit had been used, the process could be achieved in a similar timeframe but with lower risk of overheating the parts and better solder alloy flow.

This demonstration proved how fast it is to optimize the soldering process using induction heating - changing different parameters and evaluating results achieved within minutes. In addition to replacing traditional flame-based heating solutions, UltraFlex induction solutions can help reduce manufacturing costs, increase energy efficiency, improve safety, and meet lean manufacturing objectives.

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About UltraFlex Power Technologies:

UltraFlex Power Technologies (ultraflexpower.com) offers the most advanced and innovative digitally controlled induction heaters in the industry. Its compact modular and flexible systems are suitable for a wide variety of induction heating, casting and melting applications.

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