Micro Tig is welding at very low amperages with welding wire as small 0.005”. It allows extremely accurate control, minimal sink (shrinkage between the weld and parent material) undercutting and warping. Conceptually, it is like welding with a very fine hair.
The techniques used require an expert welder using a microscope to obtain extreme precision. The process builds only the damaged location with no excess weld to permit minimal machining. Besides saving time and cost, the capability often enables a repair instead of replacing an expensive part.