Kaman KD-2300 - Manual (Page 24)

KD-2300 Instruction Manual Part III: The Equipment
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21
Target Material
The essential requirement for a proper target is that it be conductive. In
addition, nonmagnetic targets offer greater stability and linearity than
magnetic targets (in particular, aluminum, copper and some 300 series
stainless steel make ideal targets).
Kaman Precision Products can optimize any Series 2300 system to work with
either a magnetic or nonmagnetic target. You will find it difficult to use a
system tuned for nonmagnetic materials with a magnetic target. With
some of the smaller sensors, it is impossible to use a mismatched target and
system without optimization through changing the bridge module.
Target Size
The size of your target relative to the sensor is very important. The target
should be a minimum of 2.5 to 3 times larger than the diameter of an
unshielded sensor and 1.5 to 2 times the diameter of a shielded sensor.
TARGET =
2.5 to 3X diameter of
an unshielded sensor
UNSHIELDED SENSOR
SHIELDED SENSOR
TARGET =
1.5 to 2X diameter of
an shielded sensor
Targets larger than the recommended size will have no effect on system
performance. A flat target that is 3 times the diameter of a sensor face will
look the same as one that is 300 times the diameter.
Using a target smaller than the recommended size will cause some
degradation in linearity and long term stability. For smaller targets,
calibration over a range less than the specified range for the sensor will
minimize and in some cases, eliminate the performance degradation. (Refer
also to Part 4: CALIBRATION for high accuracy band calibration.)
Measurements taken using targets smaller than the recommended size are
dependent on both the vertical and horizontal position of the target. A
vertical view shows a rod passing left to right (three different positions)