Lesson 1

Read the text: Machine tool

A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by machining, which is the selects removal of metal. The term machine tool is usually reserved for tools that used a power source other than human movement, but they can be powered by people if appropriately set up.

The scientific definition of a "machine" (derived from the Latin machina) is any device that transmits or modifies energy. In common usage, the meaning is that of devices having parts that perform or assist in performing any type of work. Machines normally require some energy source ("input") and always accomplish some sort of work ("output"). Devices with no rigid moving parts can be considered tools.

A machine is anything that makes work easier.

People have used mechanisms to transform one form of motion or energy into another.

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% efficient.

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.

Compound machines are composed of more elementary machines called simple machines, such as the wedge and the pulley. Machines are considered simple machines if they perform their action in one movement. These 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 earth moving equipment industries.

Machine tools can be powered from a variety of sources. Human and animal power are options, as is energy captured through the use of waterwheels. However, machine tools really began to be developed after the development of the steam engine. Today, most are powered by electricity.

Machine tools can be operated manually, or under automatic control. Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked on.

Nowadays the examples of machine tools are numerous :

* Broaching machine

* Drill press

* Gear shaper

* Hobbing machine

* Hone

* Lathe

* Milling machine

* Shaper

* Planer

* Stewart platform mills

* Grinders

When fabricating or shaping parts, several techniques are used to remove unwanted metal. Among these are:

* EDM (electrical discharge machining)

* Grinding

* Multiple edge cutting tools

* Single edge cutting tools

* Other techniques are used to add desired material. Devices that, fabricate components by selective addition of material are called rapid prototyping machines.

1. Match the left part with the right one:

1. Devices with no rigid moving parts can be considered	a) always less than 100% efficient .
2. Compound machines are composed of	b)to add desired material.
3.Several techniques are used	c) More elementary machines.
4. Functional physical machines are	d)tools.

2. Complete the sentences with the suggested words: equipment, moving, perform, support

Machines are considered simple machines if they ______ their action in one movement. These devices may also be used to ______ industrial applications, although devices entirely lacking rigid moving parts are not commonly considered machines. Hydraulics are widely used in heavy ______ industries, automobile industries, marine industries, aeronautical industries, construction equipment industries, and earth ______ equipment industries.