This article is about devices that perform tasks.
The scientific definition of a machine is any device that
transmits or modifies energy. In common usage, the meaning is restricted
to devices having rigid moving parts that perform or assist in
performing some work. Machines normally require some energy source
("input") and always accomplish some sort of work ("output"). Devices
with no rigid moving parts are commonly considered tools, or simply
devices, not machines.
People have used mechanisms to amplify their abilities since before
written records were available. Generally these devices decrease the
amount of force required to do a given amount of work, alter the
direction of the force, or transform one form of motion or energy into
another.
Modern power tools, automated machine tools, and human-operated power
machinery are tools that are also machines. Machines used to transform
heat or other energy into mechanical energy are known as engines.
Hydraulics devices may also be used to support industrial applications,
although devices entirely lacking rigid moving parts are not commonly
considered machines. Hydraulics are widely used in heavy equipment
industries, automobile industries, marine industries, aeronautical
industries, construction equipment industries, and earthmoving equipment
industries.
History
Perhaps the first example of a human made device designed to manage
power is the hand axe, made by chipping flint to form a wedge. A wedge
is a simple machine that transforms lateral force and movement of the
tool into a transverse splitting force and movement of the workpiece.
The idea of a simple machine originated with the Greek
philosopher Archimedes around the third century B.C.E., who studied the
Archimedean simple machines: lever, pulley, and screw. However the
Greeks' understanding was limited to statics (the balance of forces) and
did not include dynamics (the tradeoff between force and distance) or
the concept of work.
During the Renaissance the dynamics of the Mechanical Powers, as
the simple machines were called, began to be studied from the standpoint
of how much useful work they could perform, leading eventually to the
new concept of mechanical work. In 1586 Flemish engineer Simon Stevin
derived the mechanical advantage of the inclined plane, and it was
included with the other simple machines. The complete dynamic theory
of simple machines was worked out by Italian scientist Galileo Galilei
in 1600 in Le Meccaniche ("On Mechanics"). He was the first to understand that simple machines do not create energy, they merely transform it.
The classic rules of sliding friction in machines were discovered by
Leonardo da Vinci (1452–1519), but remained unpublished in his
notebooks. They were rediscovered by Guillaume Amontons (1699) and were
further developed by Charles-Augustin de Coulomb (1785).
Impact
Industrial Revolution
The Industrial Revolution was a period from 1750 to 1850 where changes
in agriculture, manufacturing, mining, transportation, and technology
had a profound effect on the social, economic, and cultural conditions
of the times. It began in the United Kingdom, then subsequently spread
throughout Western Europe, North America, Japan, and eventually the rest
of the world.
Starting in the later part of the eighteenth century, there began a
transition in parts of Great Britain's previously manual labor and
draft-animal–based economy towards machine-based manufacturing. It
started with the mechanization of the textile industries, the
development of iron-making techniques and the increased use of refined
coal.
Mechanization and automation
Mechanization is providing human operators with machinery that assists
them with the muscular requirements of work or displaces muscular work.
In some fields, mechanization includes the use of hand tools. In modern
usage, such as in engineering or economics, mechanization implies
machinery more complex than hand tools and would not include simple
devices such as an un-geared horse or donkey mill. Devices that cause
speed changes or changes to or from reciprocating to rotary motion,
using means such as gears, pulleys or sheaves and belts, shafts, cams
and cranks, usually are considered machines. After electrification, when
most small machinery was no longer hand powered, mechanization was
synonymous with motorized machines.
Automation is the use of control systems and information technologies to
reduce the need for human work in the production of goods and services.
In the scope of industrialization, automation is a step beyond
mechanization. Whereas mechanization provides human operators with
machinery to assist them with the muscular requirements of work,
automation greatly decreases the need for human sensory and mental
requirements as well. Automation plays an increasingly important role in
the world economy and in daily experience.
Automata
An automaton (plural: automata or automatons) is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot.
Types
The mechanical advantage of a simple machine is the ratio between the
force it exerts on the load and the input force applied. This does not
entirely describe the machine's performance, as force is required to
overcome friction as well. The mechanical efficiency of a machine is the
ratio of the actual mechanical advantage (AMA) to the ideal mechanical
advantage (IMA). Functioning physical machines are always less than 100
percent efficient.
Mechanical
The word mechanical refers to the work that has been produced by
machines or the machinery. It mostly relates to the machinery tools and
the mechanical applications of science. Some of its synonyms are
automatic and mechanic.
Simple machines
The idea that a machine can be broken down into simple movable elements
led Archimedes to define the lever, pulley and screw as simple machines.
By the time of the Renaissance this list increased to include the
wheel and axle, wedge and inclined plane.
Engines
An engine or motor is a machine designed to convert energy into useful
mechanical motion. Heat engines, including internal combustion engines
and external combustion engines (such as steam engines) burn a fuel to
create heat, which is then used to create motion. Electric motors
convert electrical energy into mechanical motion, pneumatic motors use
compressed air and others, such as wind-up toys use elastic energy. In
biological systems, molecular motors like myosins in muscles use
chemical energy to create motion.
Electrical
Electrical means operating by or producing electricity, relating to
or concerned with electricity. In other words, it means using,
providing, producing, transmitting or operated by electricity.
Electrical machine
An electrical machine is the generic name for a device that
converts mechanical energy to electrical energy, converts electrical
energy to mechanical energy, or changes alternating current from one
voltage level to a different voltage level.
Electronic machine
Electronics is the branch of physics, engineering and technology dealing
with electrical circuits that involve active electrical components such
as vacuum tubes, transistors, diodes and integrated circuits, and
associated passive interconnection technologies. The nonlinear behavior
of active components and their ability to control electron flows makes
amplification of weak signals possible and is usually applied to
information and signal processing. Similarly, the ability of
electronic devices to act as switches makes digital information
processing possible. Interconnection technologies such as circuit
boards, electronic packaging technology, and other varied forms of
communication infrastructure complete circuit functionality and
transform the mixed components into a working system.
Computing machines
Computers are machines to process information, often in the form of
numbers. Charles Babbage designed various machines to tabulate
logarithms and other functions in 1837. His Difference engine can be
considered an advanced mechanical calculator and his Analytical Engine a
forerunner of the modern computer, though none were built in Babbage's
lifetime.
Modern computers are electronic ones. They use electric charge, current
or magnetization to store and manipulate information. Computer
architecture deals with detailed design of computers. There are also
simplified models of computers, like State machine and Turing machine.
Molecular machines
Study of the molecules and proteins that are the basis of biological
functions has led to the concept of a molecular machine. For example,
current models of the operation of the kinesin molecule that transports
vesicles inside the cell as well as the myosin molecule that operates
against actin to cause muscle contraction; these molecules control
movement in response to chemical stimuli.
Researchers in nano-technology are working to construct molecules that
perform movement in response to a specific stimulus. In contrast to
molecules such as kinesin and myosin, these nanomachines or molecular
machines are constructions like traditional machines that are designed
to perform in a task.
Types of machines and related components
| Classification | Machine(s) | |
|---|---|---|
| Simple machines | Inclined plane, Wheel and axle, Lever, Pulley, Wedge, Screw | |
| Mechanical components | Axle, Bearings, Belts, Bucket, Fastener, Gear, Key, Link chains, Rack and pinion, Roller chains, Rope, Seals, Spring, Wheel | |
| Clock | Atomic clock, Watch, Pendulum clock, Quartz clock | |
| Compressors and Pumps | Archimedes' screw, Eductor-jet pump, Hydraulic ram, Pump, Trompe, Vacuum pump | |
| Heat engines | External combustion engines | Steam engine, Stirling engine |
| Internal combustion engines | Reciprocating engine, Gas turbine | |
| Heat pumps | Absorption refrigerator, Thermoelectric refrigerator, Regenerative cooling | |
| Linkages | Pantograph, Cam, Peaucellier-Lipkin | |
| Turbine | Gas turbine, Jet engine, Steam turbine, Water turbine, Wind generator, Windmill | |
| Aerofoil | Sail, Wing, Rudder, Flap, Propeller | |
| Information technology | Computer, Calculator, Telecommunications networks | |
| Electricity | Vacuum tube, Transistor, Diode, Resistor, Capacitor, Inductor, Memristor, Semiconductor | |
| Robots | Actuator, Servo, Servomechanism, Stepper motor | |
| Miscellaneous | Vending machine, Wind tunnel, Check weighing machines, Riveting machines | |
Machine elements
Machines are assembled from standardized types of components. These
elements consist of mechanisms that control movement in various ways
such as gear trains, transistor switches, belt or chain drives,
linkages, cam and follower systems, brakes and clutches, and structural components such as frame members and fasteners.
Modern machines include sensors, actuators and computer controllers.
The shape, texture and color of covers provide a styling and operational
interface between the mechanical components of a machine and its users.
Mechanisms
Assemblies within a machine that control movement are often called
"mechanisms." Mechanisms are generally classified as gears and gear
trains, cam and follower mechanisms, and linkages, though there are
other special mechanisms such as clamping linkages, indexing mechanisms
and friction devices such as brakes and clutches.
For more details on mechanical machines see Machine (mechanical) and Mechanical systems.
Controllers
Controllers combine sensors, logic, and actuators to maintain the
performance of components of a machine. Perhaps the best known is the
flyball governor for a steam engine. Examples of these devices range
from a thermostat that as temperature rises opens a valve to cooling
water to speed controllers such the cruise control system in an
automobile. The programmable logic controller replaced relays and
specialized control mechanisms with a programmable computer. Servo
motors that accurately position a shaft in response to an electrical
command are the actuators that make robotic systems possible.