Combining existing analytical models with newly developed simulation models leads to better understanding of the manufacturing processes and creates necessary conditions for optimizing them in terms of longer tool life, better surface integrity, higher production rate and reduction of production disturbances. Machining is indisputably the most common manufacturing process in manufacturing of high precision, discrete metal parts. Friction Stir Welding (FSW), which is a relatively recently developed solid state joining technique is both energy efficient and environmental friendly method. Both manufacturing processes are modeled using finite element techniques.