Mechanical engineering is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and maintain mechanical systems. It is the branch of engineering that involves the design, production, and operation of machinery. Mechanical engineering is among the prime engineering fields. The graduate job market is known to be excellent, but as mechanical engineers use math and physics practices to design and produce the worlds mechanical devices, graduates tend to be in high demand all around the world Aerospace engineer. Structural engineer.