Energy, motion, and machines — the broadest of the engineering disciplines.
Mechanical engineering is the discipline concerned with the design, analysis, and manufacture of machines and mechanical systems — anything involving force, motion, energy, heat, or fluid flow, from a single bolted joint to an entire power plant.
Mechanical engineering applies the principles of physics and materials science to design and analyze machines and the systems that power them. It is the broadest engineering field, spanning machine design, thermodynamics, fluid mechanics, heat transfer, dynamics and vibration, materials, manufacturing, and controls. Mechanical engineers size shafts and gears, select bearings and fasteners, design pressure vessels and piping, analyze stress and fatigue, and model how energy moves through engines, pumps, turbines, and HVAC and refrigeration systems.
Because its scope is so wide, mechanical engineering overlaps with many adjacent fields — HVAC, manufacturing, aerospace, automotive, and energy. The licensing path reflects this: engineers take the FE Mechanical exam, then the PE Mechanical exam in one of three depth areas — Machine Design & Materials, Thermal & Fluid Systems, or HVAC & Refrigeration. Underneath all of it is a shared toolkit of statics, dynamics, mechanics of materials, and thermal-fluid science.
Sizing shafts, gears, bearings, springs, and fasteners; stress, fatigue, and failure analysis; and material selection for strength and durability.
Energy balances, power and refrigeration cycles, combustion, and the conversion of heat to work in engines, turbines, and compressors.
Pipe and duct flow, Bernoulli and head loss, pump and system curves, and the sizing of pumps, fans, and piping networks.
Conduction, convection, and radiation; heat exchangers, fins, and thermal sizing of components and systems.
Applying thermal-fluid principles to building mechanical systems, refrigeration cycles, and ASME-code piping and pressure vessels.
Mechanical engineers design, analyze, and improve machines and mechanical systems — anything involving force, motion, energy, heat, or fluid flow. Day to day they size machine elements, run stress and thermal calculations, design piping and pumping systems, model components in CAD and FEA, and produce the drawings and documentation needed to manufacture or build a system.
Mechanical engineering covers an unusually wide range of physics-based subjects — machine design, thermodynamics, fluid mechanics, heat transfer, dynamics, materials, manufacturing, and controls — and applies them across nearly every industry, from HVAC and energy to automotive, aerospace, and manufacturing. This breadth is why the PE Mechanical exam is split into three separate depth areas.
The NCEES PE Mechanical exam offers three depth options: Machine Design & Materials, Thermal & Fluid Systems, and HVAC & Refrigeration. Candidates first pass the FE Mechanical exam, gain qualifying experience, then choose the PE depth that matches their specialty to earn a license that lets them stamp engineering work.
Common references include the ASME Boiler & Pressure Vessel Code, the ASME B31 piping codes, and ASME Y14.5 for drawing tolerances, along with ASHRAE standards for HVAC work and API/ASTM standards for materials and equipment. The NCEES FE/PE Mechanical Reference Handbook is the allowed reference during licensure exams.