Groups of Engineering Materials.

Based on their properties, this post has grouped engineering materials into:

(1.) Alloys (or Metals)
(2.) Plastic Materials.
(3.) Ceramics and Rubbers.
(4.) Composite Materials.

Alloys (or Metals).
An alloy can be defined as a metallic solid or liquid which is a mixture of 2 or more metals. For two metals to form a strong alloy,  they must be able to mix with each other in their molten state. Alloy may contain some non-metallic elements such as carbon. Examples of alloys are Steel,  Cast Iron.

Plastics.
These are organic materials containing molecules of high molecular weight which can be moulded to shape through the application of pressure at moderately high temperatures. Once moulded, some plastics may retain their plasticity while others may become hard and brittle. Examples of plastics are polyethene, nylon and bakelite.

(3.) Ceramics and Rubbers.
Ceramics are inorganic non-metallic materials which in most cases have been subjected to high temperature at some stages during manufacture. Examples of ceramics are natural and man-made glasses used to make bottles, windows and lenses, cements etc.
Rubbers are substances which have polymer molecules arranged in a manner that allows reversible extension to take place at normal temperatures. Well an example of rubber is the natural one derived from the sap of rubber tree.

(4.) Composite Materials.
Composite materials are groups of dissimilar materials combined together to form a new complex whose properties are different in type and magnitude from those of its seperate constituents. An example of a natural composite is wood which consists of cellulose bounded by lignin.  Other examples of composites are reinforced concrete and vulcanized rubber.

Materials In Engineering.

All engineering products are made up of materials. In fact almost nothing in this world useful to man is not a material which has an engineering application. For example, the concrete of highways  and the bodies of automobiles are obviously engineering materials. Most of us know the importance of electricity to our modern world. But the materials used to transmit electricity from the source of power supply to our homes are engineering materials. Even our houses are made up of engineering materials. The food we eat, the water we drink or any edible thing we take into our bodies are processed and prepared using engineering materials. So there is almost nothing that is useful and  man made to us  in this world that is not an engineering material or closely related and connected to any engineering material. Therefore we can safely conclude that the advancement in  technology is strongly dependent on the development of materials which help us to translate the engineering ideas into reality.
Seeing the importance of engineering materials, it is necessary for all engineers in all engineering fields to have a basic knowledge of engineering materials so that they will be able to select and specify the best material which has the required properties for any engineering application. For instance, looking at the earlier examples given, the materials to be used for the design and the construction of highways should be such that they can be easily processed into satisfactory and economical final products. Again they must have the required properties which will enable them to  give the desired performance during service which is high strength and durability properties that cannot be ignored when looking at the safety of life and property. So any engineer in any engineering field  needs to have a basic knowledge of engineering materials so that he/she will be able to know the best material to chose for any engineering application.  The understanding of how engineering materials behave when subjected to different conditions will enable the engineer to know the limitations of the material chosen and the modifications he has to make both in the design and manufacture of the chosen material.