What is a Machine?

Machine design is an important part of engineering applications, but what is a machine? Machine is the devise that comprises of the stationary parts and moving parts combined together to generate, transform or utilize the mechanical energy. All the machines are made up of elements or parts and units. Each element is a separate part of the machine and it may have to be designed separately and in assembly. Each element in turn can be a complete part or made up of several small pieces which are joined together by riveting, welding etc. Several machine parts are assembled together to form what we call as complete machine.

Here are some examples of the machines:

1) Lathe: It utilizes mechanical energy to cut the metals. The other types of machine tools also perform the same task.

2) Turbines: They produce mechanical energy.

3) Compressors: They use mechanical energy to compress the air.

4) Engines: They consume the fuel and produce mechanical energy.

5) Refrigerators and air-conditioners: They use mechanical engineering to produce cooling effect.

6) Washing machines: They use mechanical energy to wash the clothes.

Considering the various applications of the machines, they are classified into three main types, these are:

1) Machines generating mechanical energy: The machines generating mechanical energy are also called as prime movers. These machines convert some form of energy like heat, hydraulic, electrical, etc into mechanical energy or work. The most popular example of these machines is the internal combustion engine in which the chemical energy of the fuel is converted into heat energy which in turn is converted into mechanical work in the form of the rotation of the wheels of the vehicle. Some other examples of this group of machines are gas turbines, water turbines, steam engine etc.

2) Machines transforming mechanical energy: These machines are called converting machines because they convert mechanical energy into other form of energy like electricity, hydraulic energy etc. Some examples of these machines are electric generator in which the rotation of the shaft is converted into electrical energy, and hydraulic pump in which the rotation energy of the rotors is converted into the hydraulic energy of the fluid.

3) Machines utilizing mechanical energy: These machines receive mechanical energy and utilize it for various applications. Some examples of these machines are lathe machine that utilizes the mechanical energy to cut metals and washing machine that utilizes the rotation of the rotor for washing the clothes.

Book: Machine Design by Dr. P. C. Sharma and D. K. Aggarwal