Lotney,

Aluminum with its high thermal conductivity rate can be problimatic when localized heat is applied.

Your options depend alot on what your doing and what kind of equipment is available. An Oven is great if you can fit the part in and cover it with blankets as soon as you remove it.

Tell us more about your project.

1. Material type (Cast, Sheet, Thickness, alloy designation)

2. Joining process your likely to use

3. Are you looking to make a single repair or a production run.

Like so many other things used improperly is not a good thing.

Oxy/Acet used incorrectly can severly distort a $750,000 Turbine Rotor but we still use it.

We also use Propane/Oxy torches, Propane weed burners with out Oxygen, Induction heating coils and Resistance heating pads.

Each job determines the method of preheat.

Out in the field many times I have been with out Temp sticks or other devices to determine the preheat temp we used straight Acet to blacken the area around the weld area then turn on the Oxy and heat untill the Black dissolves away then you can weld.