Page 101 - Sensors and Control Systems in Manufacturing

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control device, or a direct interface to a computer network. This sim-
ple activity, once done successfully, will enable varieties of manufac-
turing operations to direct a combination of production plans accord-
ing to the computer-integrated manufacturing strategy.
Inductive proximity sensors are used in place of limit switches for
noncontact sensing of metallic objects. Capacitive proximity switches
are used on the same basis as inductive proximity sensors; however,
capacitive sensors can also detect nonmetallic objects. Both inductive
and capacitive sensors are limit switches with ranges up to 100 mm.
The distinct advantage of photoelectric sensors over inductive or
capacitive sensors is their increased range. However, dirt, oil mist,
and other environmental factors will hinder operation of photoelec-
tric sensors during the vital operation of reporting the status of a
manufacturing process. This may lead to significant waste and
buildup of false data.

2.5.1 Typical Applications of Inductive Proximity Sensors
Motion position detection (Fig. 2.33):
• Detection of rotating motion
• Zero-speed indication
• Speed regulation

Motion control (Fig. 2.34):
• Shaft travel limiting
• Movement indication
• Valve open/closed

FIGURE 2.33 Motion/ FIGURE 2.34 Motion
position detection with control, inductive proximity
inductive proximity sensor. sensor.