Page 35 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Section I.4 Green Design and Manufacturing

I.4 Green Design and Manufacturing

In the United States alone, 9 million passenger cars, 300 million tires, 670 million
compact fluorescent lamps, and more than 5 billion kilograms of plastic products
are discarded each year. Every three months, industries and consumers discard
enough aluminum to rebuild the U.S. commercial air fleet. Note that, as indicated
subsequently, the term discarding implies that the products have reached the end of
their useful life; it does not necessarily mean that they are wasted and dumped into
landfills.
The particular manufacturing process and the operation of machinery can each
have a significant environmental impact. Manufacturing operations generally produce
some waste, such as:

a. Chips from machining and trimmed materials from sheet forming, casting, and
molding operations.
b. Slag from foundries and welding operations.
c. Additives in sand used in sand-casting operations.
d. Hazardous waste and toxic materials used in various products.
e. Lubricants and coolants in metalworking and machining operations.
f. Liquids from processes such as heat treating and plating.
g. Solvents from cleaning operations.
h. Smoke and pollutants from furnaces and gases from burning fossil fuels.

The adverse effects of these activities, their damage to our environment and to the
Earth’s ecosystem, and, ultimately, their effect on the quality of human life are now
widely recognized and appreciated. Major concerns involve global warming, green-
house gases (carbon dioxide, methane, and nitrous oxide), acid rain, ozone deple-
tion, hazardous wastes, water and air pollution, and contaminant seepage into
water sources. One measure of the adverse impact of human activities is called the
carbon footprint, which quantifies the amount of greenhouse gases produced in our
daily activities.
The term green design and manufacturing is now in common usage in all
industrial activities, with a major emphasis on design for the environment (DFE).
Also called environmentally conscious design and manufacturing, this approach
considers all possible adverse environmental impacts of materials, processes, opera-
tions, and products, so that they can all be taken into account at the earliest stages
of design and production.
These goals, which increasingly have become global, also have led to the concept
of design for recycling (DFR). Recycling may involve one of two basic activities:

° Biological cycle: Organic materials degrade naturally, and in the simplest ver-
sion, they lead to new soil that can sustain life. Thus, product design involves
the use of (usually) organic materials. The products function well for their in-
tended life and can then be safely discarded.
° Industrial cycle: The materials in the product are recycled and reused continuously.
For example, aluminum beverage cans are recycled and reused after they have
served their intended purpose. To demonstrate the economic benefits of this ap-
proach, it has been determined that producing aluminum from scrap, instead of
from bauxite ore, reduces production costs by as much as 66% and reduces
energy consumption and pollution by more than 90%.