Brazing/Welding 2 aluminum parts

By n003lb Date 06-04-2005 04:19

Howdy,

First time poster here, and I need a little help. My brother is trying to attach a small aluminum mesh to a piece of flat aluminum bar. He is trying this with a butain soldering torch as well as a 25 watt iron and Rosin core solder. The mesh overlaps the bar a little. The problem is when he heats up the materials, the solder just sticks to the tip of the iron and won't adhear to the metals. He can't just braze it because there is no way to set the proper clearence between the parts, since the mesh actually sets on the bar. Any idea how he can do this? We are working with pretty small parts here. The bar is 1/4" wide flat aluminum folded into a "C" shape and the entire unit is only about 2 1/2" wide by about 1 1/4" tall.

Thanks for any help.
Cory

By Ed Kay Date 07-03-2005 20:36

Cory, you can't solder aluminum with lead solder. There are special aluminum rods that melt at low temperature that might work. You would have to check with a local welding supply, or maybe find it at a hardware store. You might also consider epoxy to hold the parts together.
Good luck.
Ed Kay

By swnorris (****)

Date 07-05-2005 16:47

The soldering of aluminum differs from the soldering of most other metals in several ways. The most important concern is the oxide that forms rapidly on aluminum. In most cases, this requires the use of active soldering fluxes that are specifically designed for aluminum. Non corrosive fluxes are not suitable. A second difference is that special techniques are required to obtain solder flow into certain types of joints. A third important difference is that the corrosion resistance of soldered aluminum joints is more dependent upon the composition of the solder than for similar joints in copper, brass, or steel. Alloying elements influence the solderability of aluminum. Commonly soldered aluminum alloys are 1060, 1100, 3003, 5005, 6061 and 7072. Readily soldered aluminum alloys contain no more than 1% magnesium or 5% silicon. Alloys containing greater amounts of these elements have poor flux wetting characteristics and may be rapidly attacked intergranularly by the solder. The commercial solders for aluminum can be classified into low (300-500 degrees melting range) , intermediate (500-700), and high (700-800) temperature groups.