If you have studied chemistry you will know that the periodic table contains 103 known elements.

 A large proportion of these elements are metals. Some such as gold, silver, copper and aluminium are useful in their pure state. Many elements are of little practical use to designers unless they are combined chemically with other elements to produce materials with specific properties or characteristics.

When human beings first started to use materials they relied on organic materials such as wood and bone or inorganic materials such as rock and stone, which could be found in their immediate environment.

Classifying Materials

Metals

Metallic elements form almost one quarter of the earths crust by weight. With the exception of gold all other metals are found in the form of oxides or sulphates. In order to obtain metals in any useful form, they have to be extracted from an ore (a mixture of oxides or sulphates, earth, rock and clay). This is done by heating to a high temperature in a furnace.

Early humans must have discovered the techniques for reducing metallic ores to their pure state by chance. Alloying (combining two or more metals to create a metal with enhanced properties) began in the Bronze Age and still continues to this day. SMA (shape memory alloy) is a combination of titanium and nickel which produces an alloy called nitinol. 

Nitinol is one of a growing number of 'Smart materials' which have only recently been discovered. It has the ability to be bent, stretched or distorted but will return to is original shape and cross-section when heated to a specified temperature.

Metals are classified as follows:

Polymers

Polymers (commonly called plastics) are organic materials. They exist in both natural and synthetic form. Synthetic polymers are produced from carbon-based materials such as oil, coal and natural gas. 

Natural sources of polymers such as cellulose (from plant fibres) and latex (from trees) are relatively insignificant in comparison to the synthetic production (particularly from crude oil) of the many different types of polymers available to designers and manufacturers today.

Crude oil is refined to produce naptha. Naptha is a hydrocarbon it provides the hydrogen and carbon atoms which form the basis of the 'long chain molecules' from which polymers are made. 

Sometimes two polymers are mixed together to produce a co-polymer (this is similar to the process of alloying two or more metals).

Polymers are classified as follows:

Both thermosetting and thermoplastic polymers can be reinforced with carbon or glass fibres.

Timber based materials

Natural wood, processed directly from trees is still used in large quantities. Much of this is from trees known as softwoods, which because they grow relatively quickly can be managed as a renewable resource.

Unfortunately most hardwoods are obtained from tropical rain forests which once cleared are almost impossible to replace. Hardwood trees can take a century or more to regenerate.

Sheet and board materials are increasingly made from timber by-products such as wood chips or fibre which are glued together under pressure.

Hardwoods are becoming so rare and expensive that most are used to provide thin veneers for covering less expensive boards such as chipboard or MDF when manufacturing furniture. 

Timber based materials are classified as follows:

Selecting Suitable Materials

A product designer needs to know what materials are available, how they behave in use and how they can be worked or processed during manufacture and construction. Having a good understanding of these things will help you to select suitable materials for your product designs.