How I weld Aluminium

The first major task today was to have a go at welding Aluminum for the
very first time. I used the Durafix system which is advertised as being
simple to use.

Well we have all heard that before and I must admit to some skepticism as I
prepared to have a practice on a couple of scrap aluminum pieces. I decided
to make one edge of each have a chamfer so giving me a v to fill. The process
involves cleaning up the part to be welded with the supplied stainless steel
wire brush. Then the parts need to be brought to the temperature at which
the welding rods will melt when in contact with the metal, and not the flame
of the propane.

Here is where I learnt an important (and obvious now) fact that there is a
considerable amount of heat required to get the metal to the 700 °plus
needed. The great amount of heat is made worse by holding the parts to be
welded together in the vice. As we know aluminum is a great conductor of
heat so you end up heating the parts plus the iron vice!

Well when the heat was eventually reached the welding rod was rigorously
rubbed in the indented V between the two parts and the rod flowed easily
enough into the space. After letting the whole area (!) cool down the two
pieces were inspected and there seemed to be a good weld considering the
small run or weld.

Armed with this experience I moved out into the garage and decided to hold
the casting to be welded in my 'old' B&D work bench. At least the heat
transfer problem from the trial wouldn't occur although the piece to be
heated up was much bigger than the practice piece. At least I knew it would
take some heating up and I was now prepared for that.

After grinding out a V shape in each side of the crack the casting was held in
the workmate bench and heating started. When I thought it was getting close
to temperature the flames fierceness was dropping off…..yes the gas was
running out. Quickly I got my spare cylinder out only to find it also was
empty. How I don't know but it was. So I had to go and find a supplier,
needless to say the first one only had empties himself! Eventually I returned
home with a full cylinder but a cold casting! SO the process started again
with cleaning the area to be welded being brushed hard with the supplied
stainless steel brush, the heating supplied and after several minutes the rod
was applied away form the flame and it ran into the V nicely. It was here
that I learnt my second and important lesson, if I turned the casting over,
would the weld already made drop through? Well it was too late to worry
about that now and heat was again applied to get the casting up to
temperature and the weld done as for the first one. When looking, the work
done before was undone.

I decided that the crack, which opened slightly when heated the first time,
allowed the welding rod to flow through so that was a positive but I would
redo the outside edge and accept that the inside joint would have to be held
the best I could. When allowed to cool the outside weld was done and the
inside had also a good depth of weld but it had been about to drip. So the
next time I try a repair similar to this one I will place some material over
the first repair so it has no where to go, before doing the second side. I am
sure that will make a neater and therefore stronger weld.

So what were my overall impressions?

1. You need a significant source of heating if you are repairing a large part.

2. The three steps are easy enough to remember and the kit does come with
everything you need.

3. I was considering ordering a larger amount of rods (I got 20) but they
should last for a long time, as there didn't seem to be a lot of wastage.

4. I am happy that the casting repair was done to the instructions i.e. the rod
being melted by the casting and not the flame. Therefore it should be a
strong weld, as they say it is stronger than the surrounding metal.

5. It takes longer than you think to heat the material.

Will I use it again? You bet. I think this is a serious solution to welding
aluminum and I will experiment with other repairs to learn better techniques.
So I think it was a success. Makes a change to find something that in the end
does what it says!

If you want a source for the aluminum welding kit there is an eBay link on
this page.