What is Mechanical Engineering?

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Mechanical engineers build things such as machines and tools that improve the conditions of life. (Image credit: Scorpp | Shutterstock )

Mechanical engineering is one of the oldest branches of engineering, dating back to when the first wheels were put to practical use by mounting them on an axle to make a cart. Throughout recorded history, people have been inventing and building increasingly more sophisticated devices and machines in order to improve the conditions of life. Many of the machines we encounter every day — cars, appliances, tools and climate control systems — were made possible by mechanical engineers. 

"Mechanical engineering dates to ancient Greece and China, where mechanisms like screw pumps, steam engines, clocks, seismometers and even differential gears were invented,” according to the American Society of Mechanical Engineers (ASME). Pioneers in the field — people who built the machines for which they became famous — include Archimedes (Archimedes’ screw pump, block-and-tackle pulley, etc.), Johannes Gutenberg (movable-type printing press), James Watt (steam engine), Robert Fulton (steamboat), Eli Whitney (cotton gin) and Henry Ford(automobile assembly line).

One of the most significant drivers of innovation in the field of mechanical engineering, particularly in its earliest stages, has been war, according to the Viterbi School of Engineering at the University of Southern California.

“Mechanical engineers can create basic commodities that an every-day person would use, or other highly valued items for the military or government,” the school's website states. Catapults, battering rams, chariots and siege towers were all the products of mechanical engineering. Many of the machines of modern warfare, such as armored vehicles, ships, aircraft, artillery and firearms, also owe their existence to mechanical engineers. 

What does a mechanical engineer do?

Simply put, "mechanical engineering deals with anything that moves," according to the Fu Foundation School of Engineering and Applied Science at Columbia University. Mechanical engineers still use basic components that have been known and used for centuries — such as wheels, axles, levers, screws, springs and hinges — to make machines such as vehicles, farm machinery, household appliances, robots and industrial equipment. Mechanical engineers also design sub-assemblies for these machines, including control systems and instruments as well as individual parts. 

Movement can be powered by the muscles of humans or animals, heat and pressure of combustion, hydraulic or pneumatic actuators, electromagnetism, gravity or springs of all shapes and sizes. Therefore, a mechanical engineer must be familiar with all of these basic motion and power components in order to design more complex devices. For instance, in an automobile, the starter motor uses electromagnetism; the engine is powered by expansive pressure from the combustion of gasoline; the power steering, brakes and automatic transmission use hydraulic pressure; and the suspension system uses springs. 

Mechanical engineering is one of the broadest engineering disciplines, according to the U.S. Bureau of Labor Statistics (BLS). Mechanical engineers must have a basic working knowledge of many other areas of engineering, including structural, aerospace, computer and electrical engineering. Additionally, they should be familiar with instrumentation and control, manufacturing processes and materials in order to design devices that can be built efficiently and at a reasonable cost. 

Critical skills needed in mechanical engineering are an in-depth understanding of physics, mathematics and materials. This knowledge allows engineers to calculate failure conditions based on the dimensions of a part, the properties of its material and the conditions under which it will operate. An engineer can then specify the required dimensions and materials of a part so it can withstand a given force. 

Engineers work with many types of materials, including metals, ceramics, polymers and composites. In "Mechanical Behavior of Engineering Materials" (Springer, 2007), Joachim Roesler, Harald Harders and Martin Baeker write that it is very important for mechanical engineers to study the mechanical behavior of materials. Knowing the properties of these materials, such as their density, hardness, tensile strength, bulk modulus and bending strength, allows mechanical engineers to calculate how these materials will perform under stresses such as compression, tension, bending and twisting as well as under various environmental conditions of temperature, pressure, corrosive gasses and liquids, and even radiation. They also need to be able to predict how these materials will stand up over an extended period of time. 

More and more, mechanical engineers rely on computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, so proficiency with computers is essential. According to theUniversity of Pittsburgh website, "To design all the machines that use and produce power, today's mechanical engineers use CAD/CAM drawing programs to draft their designs exactly before any manufacturing and testing is done." In addition to speeding up the drafting process, CAD systems allow for quick and easy modifications of designs, three-dimensional (3D) visualization of finished parts and assemblies, and rapid prototyping using 3D printing and computer-aided manufacturing (CAM) software with computer numeric controlled (CNC) machine tools. A comprehensive list of necessary skills and abilities for mechanical engineers can be found at MyMajors.com

Mechanical engineering jobs and salary

According to the BLS, "Mechanical engineers generally work in professional office settings. They may occasionally visit worksites where a problem or piece of equipment needs their personal attention. Mechanical engineers work mostly in engineering services, research and development, manufacturing industries, and the federal government." 

For most jobs, mechanical engineers need at least a bachelor’s degree in engineering, and many employers, particularly those that offer engineering consulting services, also require certification as a Professional Engineer. A master's degree is often required for promotion to management, and ongoing education and training are needed to keep up with advances in technology, materials, computer hardware and software, and government regulations. Additionally, many mechanical engineers belong to the American Society of Mechanical Engineers

According to Salary.com, as of July 2014 the salary range for a newly graduated mechanical engineer with a bachelor's degree is $52,626 to $74,524. The range for a mid-level engineer with a master's and five to 10 years of experience is $73,238 to $108,609; and the range for a senior engineer with a master's or doctorate and more than 15 years of experience is $95,251 to $141,806. Many experienced engineers with advanced degrees are promoted to management positions or start their own businesses where they can earn even more. 

The field of mechanical engineering is expected to grow. The BLS states, "Employment of mechanical engineers is projected to grow 5 percent from 2012 to 2022, slower than the average for all occupations. Job prospects may be best for those who stay abreast of the most recent advances in technology." Having good grades from a highly rated institution should give a job seeker an advantage over the competition. 

Look for top-rated mechanical engineering programs at TopUniversities.com.

Jim Lucas is a freelance writer and editor specializing in physics, astronomy and engineering. He is general manager of Lucas Technologies

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Jim Lucas
Live Science Contributor
Jim Lucas is a contributing writer for Live Science. He covers physics, astronomy and engineering. Jim graduated from Missouri State University, where he earned a bachelor of science degree in physics with minors in astronomy and technical writing. After graduation he worked at Los Alamos National Laboratory as a network systems administrator, a technical writer-editor and a nuclear security specialist. In addition to writing, he edits scientific journal articles in a variety of topical areas.