1. Base-metal preparation:
To weld aluminum alloys, operators must take care to clean the base material and remove any aluminum oxide and hydrocarbon contamination from oils or cutting solvents or NC machines coolants. Aluminum oxide on the surface of the material melts at about 2035o C while the base-material aluminum underneath will melt at 650o C. Therefore, leaving any oxide on the surface of the base material will inhibit penetration of the filler metal into the work piece. To remove aluminum oxides, use a stainless-steel bristle wire brush (and/or grinding) or solvents and etching solutions. If grinding is used for cleaning/preparing weld areas it should be paid attention to the brand used since some grinding wheels use an organic binder that leaves a residue behind, that will possibly cause weld porosity. Thus, it is recommended to test the particular brand of grinding wheels before actual use, in a welding test work piece
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