Automating Manufacturing Systems - Process Control and ...

discrete sensors - 4.19
ure 4.22. These values show the percentage of incident light on a surface that is reflected.
These values can be used for relative comparisons of materials and estimating changes in
sensitivity settings for sensors.
Reflectivity
nonshiny materials
shiny/transparent materials
Kodak white test card
white paper
kraft paper, cardboard
lumber (pine, dry, clean)
rough wood pallet
beer foam
opaque black nylon
black neoprene
black rubber tire wall
clear plastic bottle
translucent brown plastic bottle
opaque white plastic
unfinished aluminum
straightened aluminum
unfinished black anodized aluminum
stainless steel microfinished
stainless steel brushed
90%
80%
70%
75%
20%
70%
14%
4%
1.5%
40%
60%
87%
140%
105%
115%
400%
120%
Note: For shiny and transparent materials the reflectivity can be higher
than 100% because of the return of ambient light.
Figure 4.22
Table of Reflectivity Values for Different Materials [Banner Handbook of
Photoelectric Sensing]
4.3.4 Capacitive Sensors
Capacitive sensors are able to detect most materials at distances up to a few centimeters.
Recall the basic relationship for capacitance.
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