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OAW Aluminum Welding

Part of racing is crashing so, being able to repair some of the broken bits yourself is obviously a good thing. I'm not going to go into a long discussion about welding because there's way too much and I know way too little so, I'll summarize: Bike's tend to have alot of aluminum on them. To weld aluminum you either need a TIG welder, which is far and away the best method but is way out of my price range, or to learn the nearly forgotten art of welding aluminum with gas. A gas rig is cheap and versatile. It can cut, heat (for bending) and weld.

Back during WWII they used Oxy-Hydrogen because Acetylene was not avialable and it burns a little cooler but, using the more common Oxy-Acetylene has it's advantages. Special eyewear from TM technologies is required to remove the sodium orange flare caused by the flux.

The problem with aluminum is that it's a very good conductor of heat and doens't show color as it's heated. When you get the edge to melting temperature, the whole piece is nearly melting temperature. It is very common to think you are going to weld an aluminum item, and have the entire thing melt into a puddle instead. I've done it plenty of times.

I've been told that one trick it to cover the weld area with soot from a carburizing flame prior to beginning to weld as the carbon will burn off as you're approaching the melting point. Remember to use a slighlty reducing flame on aluminum and to push the weld.

Here's a summary pirated from various websites:

WELDING RULES
Note: The following procedure is for oxy acetylene, because of the more technical nature and varied availability of hydrogen. The rules are simple. Follow them or fail!
  1. Open the oxygen bottle fully to seat the upper packing, then just crack the acetylene. Set regulators to equal pressures, from 2 to 5 pounds each, with smaller tips needing lower pressures.
  2. Choose a torch tip one size larger than would be used on steel, i.e. If choosing a 00 (double ought) tip for .040 steel sheet, then move up to an 0 tip for .040 aluminum sheet.
  3. If oily, clean the material with solvent, lacquer thinner. or alcohol. Scrub with stainless brush on both sides just prior to welding.
  4. Flux either the rod (or wire), or the part -- or, in extreme cases, both. The flux will be a white powder which will be mixed 1/3 with either 2/3 water or alcohol.
  5. Safety precautions such as eye protection, adequate ventilation, and keeping one's head out of the fumes, are recommended.
  6. Choose the proper filler metal for the alloy to be welded. Common weldable aircraft alloy sheetmetals are shown in Metal Filler Selection Chart. Hollow, flux filled rod, was made available years ago, but aside from the questionable alloy, it had the persistent bad habit of neatly dividing itself, building up the edges of the joint without joining them together.
Metal Filler Selection Chart
Base
Metals
1100
3003
5005505250866061
60614043(A)
4047
4043(A)
5183
5356
5554(D)
5556
5654(C)
5356
5183
5554
5556
5654(C)
4043(A)
5356
5183
5556
4043(A)
4047
5183
5654(C)
5554(D)
5556
5356
50865356
4043(A)
5356
5183
5556
5356
5183
5556
5356
5183
5556
 
50525183
5356
5556
4043(A) (B)
4043(A)
5183
5356
5556
4047
5654(C)
5183
5356
5554(D)
5556
4043
  
50055183
5356
5556
4043(A) (B)
5183
5356
5556
4043(A) (B)
   
External Links:
tinmantech.com - Videos, books and supplies / equipment for aluminum gas welding.
bikewebsite.com - Instructions for welding aluminum with gas.
metalshapers.org - Antoher tutorial

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July 09, 2010