IRt/c infrared thermocouples have quickly become
the sensors of choice for monitoring and controlling
both web and roller temperatures. Here are some
tips on accurate roller temperature measurement.
1. Measuring Uncoated Metal
or Chrome Rolls
Shiny, uncoated metal rolls are a difficult surface
for any infrared temperature sensor to properly
measure, because the sensor is presented with
too many environmental reflections. The solution
is to simply paint a small black stripe around the
circumference of an unused end of the roller. Aim
the IRt/c sensor at the black paint stripe. It will then
measure the temperature accurately and reliably
regardless of changes in the surface conditions of
the rest of the roller. If there is very little space on the edge of the roller, move the sensor closer and
paint a very small black stripe. The minimum spot
size of the IRt/c is 8 mm (0.3”), and for the IRt/c.3x it
is 6 mm (0.25”) when the sensor is brought close to
the surface.
2. Measuring Dull Metal Rollers
Dull metal rollers can provide a reliable signal.
However, it is best to test the surface, as its
emissive properties may be changed by dirt,
moisture, cleaning, etc. When in doubt, it is best to
simply paint a stripe to eliminate these variations.
3. Measuring Non-Metallic
Surfaced Rollers
These will provide a reliable IR signal at any point
the IRt/c is aimed. No painted stripe is required.