Machine

A machine is a thermodynamic system that uses power to apply forces and control movement to perform an action. Machines help us do work more easily and efficiently. They can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power.

Throughout history, people have created machines to make tasks easier. During the Renaissance, natural philosophers identified six simple machines, which are basic devices that help move heavy loads. These simple machines form the foundation for more complex machines we use today.

Modern machines are found all around us. They include many types of vehicles, such as trains, automobiles, boats, and airplanes. We also use machines in our homes and offices, like appliances and computers. In farms, factories, and even in automated systems, machines help complete important tasks quickly and accurately, including farm machinery, machine tools, factory automation, and robots.

Etymology

The word machine comes from Middle French, which got it from Latin machina. Latin borrowed this word from Greek, where it meant a clever device or tool. Over time, the idea of a machine grew to include tools and devices that help us do work, like levers and wheels. By the 1700s, people started using the word to describe any tool that could move things or make work easier.

History

The hand axe, made by shaping flint, is one of the oldest tools and a simple machine called a wedge. Simple machines help us do work by changing the force or direction of movement. Other simple machines include the inclined plane (a ramp), the wheel and axle, the lever, the pulley, and the screw. These machines were invented thousands of years ago in places like Mesopotamia and ancient Egypt.

Later, people created machines powered by wind, water, and steam. These new machines helped make tasks easier and faster. During the Industrial Revolution, machines changed how people lived and worked, leading to big changes in factories, transportation, and everyday life.

Simple machines

Main article: Simple machine

Simple machines are basic tools that help us do work more easily. Long ago, thinkers like Archimedes identified simple machines such as the lever, pulley, and screw. During the Renaissance, more simple machines were added, including the wheel and axle, wedge, and inclined plane.

These machines make work easier by changing the force or direction of a push or pull. For example, a lever pivots on a point called a fulcrum, allowing a small force to lift a heavy object. A wheel helps move things by rolling, reducing the effort needed to push or pull a load. Simple machines are the building blocks for more complex tools and machines we use today.

Mechanical systems

A mechanical system uses power to perform tasks by applying forces and controlling movement. Modern machines include a power source and actuators that create forces and motion, a system of mechanisms that shapes this motion for a specific purpose, a controller with sensors to guide the machine, and an interface for an operator using levers and switches.

The term "mechanical" describes skills in using tools or science related to movement and forces, as studied in mechanics. Machines help us understand how devices from simple levers to cars and robots work by showing how forces and motion create useful power.

Power sources

Human and animal effort were the original power sources for early machines. Over time, people developed many ways to harness natural forces and energy.

Waterwheels appeared around the world around 300 BC to use flowing water to create motion for tasks like milling grain. Today, modern water turbines use water to produce electricity.

Windmills captured wind power for milling. Now, wind turbines also generate electricity, which powers many machines.

Engines come in many types. A steam engine uses heat to create motion, while automobile engines burn fuel to power cars. Jet engines use burning fuel to create thrust for airplanes.

Power plants generate electricity using heat from coal, natural gas, or nuclear reactions. This electricity is sent through transmission lines for people and industries to use.

Motors use electric current to create movement, from simple machines to complex robotic systems.

Fluid Power systems use pumps to move water or air to create linear motion.

Electrochemical sources like batteries, solar cells, and thermoelectric generators also provide power, each using different methods to convert energy into usable forms.

Mechanisms

The mechanism of a mechanical system is made from parts called machine elements. These parts give the system its shape and help control how it moves.

Some important parts that help control movement are gears and gear trains, which include belt drives and chain drives. There are also special parts like linkages, indexing mechanisms, and escapements. These parts work together to make machines move in useful ways.

Machine elements

The basic parts of a machine are called machine elements. These parts come in three main types: structural parts, mechanisms, and control parts. Structural parts include frames, bearings, splines, and seals. These help hold the machine together and let it move smoothly. For example, bearings help manage movement and reduce friction, while springs can hold parts in place or act like a suspension. Fasteners like screws and bolts are also important for putting machine parts together.

Mechanisms control how the machine moves. This includes things like gears, belts, chains, and levers. Control parts, such as buttons, switches, and sensors, help operate the machine. Even the shape and color of a machine’s cover can be important, making it easier and more pleasant for people to use.

Controllers

Controllers use sensors, logic, and actuators to help machines work well. A famous example is the flyball governor, which controls the speed of a steam engine. Other examples include thermostats that open valves to cool things down when they get too hot, and cruise control in cars that keeps the speed steady. Programmable logic controllers are computers that take the place of old-style relays to control machines. Servomotors are special motors that move parts of a machine exactly where they should go, making robotic systems possible.

Computing machines

Charles Babbage designed machines in 1837 to calculate logarithms and other math functions. His Difference engine was an advanced mechanical calculator, and his Analytical Engine was an early version of the modern computer, although these larger designs were never finished during his lifetime.

The Arithmometer and the Comptometer were mechanical computers that came before modern digital computers. Today, models used to study computers are called State machines and Turing machines.

Main articles: Difference engine, Analytical Engine, Modern digital computers, State machine, Turing machine

Molecular machines

Inside living cells, special molecules act like tiny machines. For example, myosin helps muscles contract by changing shape when it gets energy. Another molecule, kinesin, moves things inside cells along tiny structures. There are also machines that make energy, like ATP synthase, which creates the cell's energy source. Other machines help read and copy the cell's instructions, such as DNA polymerases and the ribosome that builds proteins. These natural machines are much more complex than any we can build artificially.

Impact

Main articles: Mechanization and Automation

Mechanization means using machines to help people with hard physical work. Instead of using just hand tools, modern machines include gears, pulleys, and motors that make work easier and faster. After electricity became common, most small machines were powered by motors instead of being hand-powered.

Automation uses computers and control systems to do jobs with little or no human help. It goes beyond just using machines to assist people; it can actually do the work on its own. Automation is very important in factories and is becoming a bigger part of our everyday lives.

Main article: Automaton

An automaton is a machine that operates by itself. The term is sometimes used to describe a robot, especially one that can work independently. One early example of a toy automaton was patented in 1863.

Mechanics

Hero of Alexandria's work on Mechanics looked at how to lift heavy weights. Today, mechanics is about understanding the forces and movement in mechanical systems. This includes studying how things move (kinematics) and how forces affect their motion.

The movement of machines can be studied by thinking of their parts as stiff, unchanging objects. This helps simplify the math used to predict how these parts will move and react when forces are applied. By using basic physics principles, scientists and engineers can simulate how machines will behave in real life, which is important for designing everything from cars to robots.

Machine design

Machine design is about planning and creating machines. It has three main parts. First is invention, where people find a need and develop ideas to make a new machine. Next is performance engineering, which focuses on making the machine work better and be easier to maintain. Finally, there is the recycle phase, where old machines are taken apart and their parts are reused.