manufacturing technique is greatly influenced by the production volume.
The different production volume classifications are discussed elsewhere
but in this section, I am going to look at how automation influences manufacturing
and the role of CAD/CAM in the process.
have changed everything. They are not yet capable of creating things or
coming up with ideas. A computer has yet to have a number one hit or be
signed up by a leading fashion house but it will probably happen in our
lifetime. Instead computers have made the lives of designers and manufacturers
much, much easier.
now has access to the internet as a research tool,
can communicate with a client using email or video conferencing,
can turn sketches into 3-D computer modelled renderings (Pro-Desktop).
create files that can be sent to rapid modelling devices (stereo lithography)
that will enable them to handle an accurate prototype version of their
use computer models to test engineering properties of their design (every
major car manufacturer will "crash" a computer generated model
of a car before going to the enormous trouble of actually building one
and sending it hurtling into a concrete wall at 40 mph).
can use the CAD files and send the data to a computer-numerically controlled
(CNC) machine to manufacture that component. (Be aware, though, that this
is a fairly slow, wasting process and so does not lend itself to mass
uses computer controlled machinery to eliminate operator error, reduce
labour costs, replace humans in hazardous environments, extend tool working
life, improve flexibility at a more predictable cost,
uses computer controlled machinery to massively improve consistency and
therefore quality with virtually all machines using feedback from sensors
to monitor their own performance,
uses ICT keep track of stock control and to automatically respond to orders
and generate orders for bought-in components (see "just-in time")
The term automation
refers to a wide variety of systems and processes that operate with little
or no human intervention. In the most modern automation systems, control
is exercised by the system itself, through control devices that sense
changes in such conditions as temperature, rate of flow, and volume, and
then command the system to make adjustments to compensate for these changes.
Most modern industrial operations are too complex to be handled manually
or even with simple machines under manual control.
developed as a result of advances in the design of a machine. Although
early machines were often complicated, most were designed to operate under
a specific set of conditions; when these conditions changed, a manual
adjustment was necessary to assure proper operation. This was not a major
shortcoming, since the machines operated at relatively low speeds. During
the Industrial Revolution of the late 1700's and the 1800's, however,
more sophisticated machines were developed and applied to situations requiring
a faster response than was possible with manual adjustment. This need
led to the concept of automation.
Automation was quickly recognised as a valuable way to assure efficiency
and accuracy in manufacturing processes. The chemical industries developed
the technology of automation to regulate variables such as pressure and
temperature that are involved in the production of chemicals. The food
industries found that packaging, bottling, and sealing operations, as
well as the production of food products, could be accomplished more efficiently
by the use of automated systems. The methods of automation were refined
with the development of aircraft guidance systems and automatic pilots.
The development of digital computers, which can monitor external conditions
and make appropriate adjustments to a system, added further impetus to
the applications of automation. Today, through automation, an entire oil
refinery can be operated by just four persons. Industrial robots perform
numerous functions on assembly lines, and automated spacecraft on deep-space
probes are programmed automatically to make adjustments in operations.
An automated system adjusts its operations in response to changing external
conditions in three steps: measurement, evaluation, and control.
In order for an automated system to respond to the external environment,
it must be able to measure the physical variables in that environment.
Thus, if flow rate is to be controlled, a measurement must be made to
determine what the flow rate is. If a complex assembly procedure is to
occur, a measurement or series of measurements must be made to define
the present state of the assembly. These measurements supply the system
with information known as feedback, because the information is fed back
to the input of the system and used to exercise some control over it.
For example, if the process is self-guidance, the feedback will include
the system's location, speed, and acceleration.
The measured information is evaluated in order to determine if corrective
action must be initiated. Thus, if a spacecraft evaluates its position
and finds itself to be off course, a course correction must be made; the
evaluation function also determines exactly how long and in what direction
a rocket should be fired to correct the course.
The last step of automation is the action resulting from the measurement
and evaluation operations. Thus, the rocket gets an appropriate signal
to fire and thereby changes the path of the spacecraft.
In many automation systems, these operations may be difficult to identify.
A system may involve the interaction of more than one control loop - that
is, a loop in the path of the signal from the output back to the input.
All systems, however, include the steps of measurement, evaluation, and
Automation is used in numerous industries throughout the world. Some industries
have become more automated than others, and some devices could not work
at all without automated features. In many cases, specific applications
of the principles of automation have led to new fields.
The application of the principles of automation to the control of continuous
manufacturing operations is called process control. It is used extensively
in the chemical and petrochemical industries, where gas and liquid temperatures,
flow, pressure, reaction rates, and many other characteristics must be
controlled. Some plants have become so automated that human involvement
is needed only to monitor the operation for non routine conditions.
Many industrial operations require a device, called a servomechanisms,
to control such simple operations as the rotational rate of motor shafts,
the amount of current, hydraulic or pneumatic pressure within a system,
or the position of a valve. Servomechanisms function through a feedback
process. They are usually actuated by changes in a mechanical situation,
although some complex servomechanisms are set in motion by electric or
The use of automated machines that can be programmed to perform different
jobs under various operating conditions has recently become widespread.
These machines can properly be called industrial robots. Robots are employed
to drill, machine, and partially assemble automobile engines. By reprogramming
the controls or computer that oversees the operation, the same machines
might be used to align and assemble washing machines. The spacecraft sent
to the Moon and on deep-space missions are also types of robots. Although
radio contact is maintained with these craft, the distances involved are
so great that the craft must incorporate devices that can adjust operations
- based on the conditions encountered - without human commands.
As technology continues to be developed and improved, more and more of
the routine activities of business and industry will be taken over by
automated systems. Microcomputers, based upon the integrated circuit,
are already causing a vast change in the applications of automation; even
a device as simple as a washing machine can be put under computer control
and thus be programmed to respond to a variety of environmental conditions.
The continued deployment of automated systems will replace some traditional
employment opportunities for people, but new opportunities will be established.
Indeed, as automation is extended, it will become necessary to evaluate
its effect on society.
in durable miniature systems for computing, mobility, and energy storage
have made the robot of science fiction a near reality. It is likely that
future societies will see the first practical robot capable of interacting
with human beings. The key characteristic of such a completely automated
machine will be self-adaptability, the capacity to evaluate a new overall
condition and decide upon a course of action. Realising this potential
will require new developments in computer algorithms, pattern recognition,
and control functions. The use of computers to design and manufacture
complex systems is becoming increasingly common. CAD/CAM systems are now
capable of designing and controlling entire manufacturing processes. The
development of interactive robots will undoubtedly require the use of
even more highly sophisticated CAD/CAM systems.
A robot may be defined as a completely self-controlled device consisting
of electronic, electrical, or mechanical units; more generally, it is
a machine devised to function in place of a living agent. Most robots
sit alongside assembly lines and perform such tasks as welding, painting,
and inspection. In the field of CAD/CAM, robotic structures have been
used to manufacture such things as integrated circuits and solid models.
Japan is both the leading maker and user of robots, with a majority of
them employed on automobile assembly lines. In general, such robots do
not have the ability to learn new tasks. Instead they perform carefully
orchestrated procedures guided by a computer program. Manufacturers are
seeking to develop more completely computer-integrated manufacturing (CIM)
processes. These processes would involve increasingly autonomous robots
equipped with vision and touch sensors and able to share learned data
with one another.