Page 112 - Sensors and Control Systems in Manufacturing

Classification and Types of Sensors

FIGURE 2.58 Sensing range variation—with temperature. 73

2.6.7 Surrounding Conditions
Several environmental factors must also be considered in order to
obtain reliable information from inductive proximity sensors. These
surrounding factors are:
• Embeddable mounting. The shielded sensor in Fig. 2.59 is often
referred to as a flush-mounted sensor. Shielded sensors are not
affected by the surrounding metal.
• Flying metal chips. A chip removed from metal during milling
and drilling operations may affect the sensor performance
depending on the size of the chip, its location on the sensing
face, and type of material. In these applications, the sensor
face should be oriented so that gravity will prevent chips
from accumulating on the sensor face. If this is not possible,
then coolant fluid should wash the sensor face to remove the
chips. Generally, a chip does not have sufficient surface area
to cause a sensor to turn on. If a chip lands on the center of the
sensor face, it will have a negligible effect, but elsewhere on
the sensor face, it will extend the range of the sensor.

FIGURE 2.59 Embeddable and nonembeddable sensors.