124 Section 3 Selecting Appropriate Materials
and alloys. Other types of engineering emphasize
performance and applications. Examples would be
chemical engineers, process engineers, and product
engineers.
Most materials engineers work in various types
of manufacturing. These types are primarily metal
production and processing, electronic and electrical
equipment, transportation equipment, and indus-
trial machinery and equipment. Materials engineers
also work in service industries such as research and
testing, and for federal and state governments.
Of all the materials in use today, the most com-
mon is metal. Its importance is evident when one
realizes that not a moment in our day goes by that
we are not using something made of metal. Metal
is also the most recycled material in the world. The
American Iron and Steel Institute points out that
steel is the most recycled material in the United
States, with the overall recycling rate typically over
65 percent. This percentage is higher than any other
recycled material and total tons recycled are greater
than all other materials combined.
Why Some Materials Are Used
Instead of Others
There are thousands of different materials used
today in the production of hard good manufactured
products, also known as durable goods. Twenty
years ago it would have been easy to make a fairly
accurate statement about the percentage of materi-
that could be attributed to the final cost of a als
product. In the time period from 1980 to 2000, about
50 percent of the final cost of most products was for
materials. Today, many specialized markets such as
aerospace, defense, and transportation require high
performance composites and exotic metals, raising
the material costs well above the 50 percent level.
One of the major factors that influence material
selection is tradition. If a company has been making
a product like a cell phone out of plastic, then it is
difficult for them to shift to another material. This
is because the company has invested in equipment,
knowledge, and training dedicated to processing
and forming plastic materials. It is much more likely
that if changes are anticipated, the company will
gradually transition to the use of new materials.
Market research is also a major driver influenc-
ing selection of materials for a particular product.
Surveys are conducted to determine what type of
product has the most appeal, and what types of
materials are preferred by the end users. Seldom
do manufacturers engage in a bold new venture,
investing in products made of unique materials,
without extensive market research. Usually small
production runs of a new product are conducted
to test the market before significant investment is
made. When the time appears right for a shift to
new materials, a careful analysis must be made in
terms of the cost, availability, performance, and
environmental impact.
There is no need to consider materials for
a product if it will fail under use. It must pass
the test of reliability, and perform consistently
throughout the product’s life cycle without failure.
Therefore, it is important to evaluate the perfor-
mance of the material being considered under the
same conditions as would be expected in the user’s
environment.
There are generally three performance crite-
ria that are important to the selection of materials:
mechanical properties, chemical properties, and
physical properties.
• Mechanical properties include hardness, tensile
strength, wearability, and toughness. An inter-
esting aspect of mechanical properties is that it
is the only one of the three performance criteria
that can be altered by a manufacturer. As an
example, when a screwdriver is being made,
the blade is formed when the metal is soft. The
blade is then heat-treated to make it hard so
that it does not distort or bend during use. The
mechanical property of hardness is controlled
by the toolmaker.
• Chemical properties address the density and
classification information such as corrosion
resistance and flammability. Data such as atomic
number, atomic symbol, atomic weight, electron
configuration, and oxidation states are found in
the Periodic Table of Elements, also known as the
Periodic Table of Chemical Elements.
• Physical properties include the material’s melt-
ing point, boiling point, and its behavior when
exposed to heat, light, or electrical energy.
When it is determined that the material will
perform reliably as desired, then it is time to move
to the next level of analysis—cost. If the material is
expensive, naturally the product costs will escalate,
possibly to a point where the product may not be sold.
Cost of the material is a factor that relates directly
to availability of the material. Some firms purchase
and alloys. Other types of engineering emphasize
performance and applications. Examples would be
chemical engineers, process engineers, and product
engineers.
Most materials engineers work in various types
of manufacturing. These types are primarily metal
production and processing, electronic and electrical
equipment, transportation equipment, and indus-
trial machinery and equipment. Materials engineers
also work in service industries such as research and
testing, and for federal and state governments.
Of all the materials in use today, the most com-
mon is metal. Its importance is evident when one
realizes that not a moment in our day goes by that
we are not using something made of metal. Metal
is also the most recycled material in the world. The
American Iron and Steel Institute points out that
steel is the most recycled material in the United
States, with the overall recycling rate typically over
65 percent. This percentage is higher than any other
recycled material and total tons recycled are greater
than all other materials combined.
Why Some Materials Are Used
Instead of Others
There are thousands of different materials used
today in the production of hard good manufactured
products, also known as durable goods. Twenty
years ago it would have been easy to make a fairly
accurate statement about the percentage of materi-
that could be attributed to the final cost of a als
product. In the time period from 1980 to 2000, about
50 percent of the final cost of most products was for
materials. Today, many specialized markets such as
aerospace, defense, and transportation require high
performance composites and exotic metals, raising
the material costs well above the 50 percent level.
One of the major factors that influence material
selection is tradition. If a company has been making
a product like a cell phone out of plastic, then it is
difficult for them to shift to another material. This
is because the company has invested in equipment,
knowledge, and training dedicated to processing
and forming plastic materials. It is much more likely
that if changes are anticipated, the company will
gradually transition to the use of new materials.
Market research is also a major driver influenc-
ing selection of materials for a particular product.
Surveys are conducted to determine what type of
product has the most appeal, and what types of
materials are preferred by the end users. Seldom
do manufacturers engage in a bold new venture,
investing in products made of unique materials,
without extensive market research. Usually small
production runs of a new product are conducted
to test the market before significant investment is
made. When the time appears right for a shift to
new materials, a careful analysis must be made in
terms of the cost, availability, performance, and
environmental impact.
There is no need to consider materials for
a product if it will fail under use. It must pass
the test of reliability, and perform consistently
throughout the product’s life cycle without failure.
Therefore, it is important to evaluate the perfor-
mance of the material being considered under the
same conditions as would be expected in the user’s
environment.
There are generally three performance crite-
ria that are important to the selection of materials:
mechanical properties, chemical properties, and
physical properties.
• Mechanical properties include hardness, tensile
strength, wearability, and toughness. An inter-
esting aspect of mechanical properties is that it
is the only one of the three performance criteria
that can be altered by a manufacturer. As an
example, when a screwdriver is being made,
the blade is formed when the metal is soft. The
blade is then heat-treated to make it hard so
that it does not distort or bend during use. The
mechanical property of hardness is controlled
by the toolmaker.
• Chemical properties address the density and
classification information such as corrosion
resistance and flammability. Data such as atomic
number, atomic symbol, atomic weight, electron
configuration, and oxidation states are found in
the Periodic Table of Elements, also known as the
Periodic Table of Chemical Elements.
• Physical properties include the material’s melt-
ing point, boiling point, and its behavior when
exposed to heat, light, or electrical energy.
When it is determined that the material will
perform reliably as desired, then it is time to move
to the next level of analysis—cost. If the material is
expensive, naturally the product costs will escalate,
possibly to a point where the product may not be sold.
Cost of the material is a factor that relates directly
to availability of the material. Some firms purchase