Page 425 - Sensors and Control Systems in Manufacturing

CHAPTER 8

Sensors in

Flexible

Manufacturing

Systems

8.1 Introduction
Flexibility has become a key goal in manufacturing, hence the trend
toward flexible manufacturing systems. These are designed to pro-
duce a variety of products from standard machinery with a minimum
of workers. In the ultimate system, raw material in the form of bars,
plates, and powder would be used to produce any assembly required
without manual intervention in manufacture. Clearly, this is a good
breeding ground for robots.
However, it should be emphasized that the early FMSs are in fact
direct numerical control (DNC) systems for machining. And it must
be acknowledged that an NC machine tool is really a special-purpose
robot. It manipulates a tool in much the same way as a robot handles
a tool or welding gun. Then, with no more than a change in program-
ming, it can produce a wide range of products. Moreover, the control-
lers for robots and NC machines are almost the same. But for an NC
machine to be converted into a self-supporting flexible system, it
needs some extra equipment, including a handling device. It then
forms an important element in an FMS.
The principle of flexible manufacturing for machining operations
is that the NC machining cells are equipped with sensors to monitor
tool wear and tool breakage. Such cells are able to operate unmanned
so long as they can be loaded by a robot or similar device since the

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