The basic types of welds are fillet, square, and grooved. Weld strength can be upto the strength of the underlying material. To improve overall system robustness it is better to increase material thickness rather than over specifying the weld. The surface to be welded needs to be clean and degreased and any foreign debris should be removed. In the case of hot-rolled steel or aluminum, wire brushing may need to be done to remove scales and oxides, for the highest quality welds.
Weld distortion occurs whenever a weld is done.
Parts should be designed with features that are self-locating with respect to mating parts. This removes the need for dedicated fixtures and its costs. Fixtures also introduce additional tolerances due to deflections imposed on the parts by the clamping pressure. Welds locations should be located with operator access in mind. If it is not accessible to a weld electrode, it is not weldable.