FMT Equipment has developed of a new roundness measurement method of large rolls rotating in their own bearings in a roll grinding machine. Between mechanical designs and mathematical procedures, run-out can be eliminated from a measurement. And even more importantly, periodic motion from the bearing clearance or other external sources can be measured and separated from the roundness measurement.



1. The above animation shows how movement of the roll center causes an oval grind shape.
2. Once the motion is ground to the roll surface as oval shape and the roll keeps moving periodically, then zero is measured on the wheel side and double the error on the back side.
3. Unless the motion is compensated by moving the wheel head, or the movement is taken out in bearings, the roll cannot be ground round.
4. The RollTrack system can measure the motion and then compensate for it even before the error is ground to the roll. See the animation below.

Circular Roll Measurement Principle

A single probe is required to measure run-out and roundness of a cylinder if the center of rotation is fixed. The run-out and roundness can be separated mathematically. However, there usually is some motion when grinding a large roll in its bearings. or supported on roll journals on babbits

If a disturbance is periodic and matches the roll rotational frequency, then this disturbance is ground into the roll surface. If the measuring probe is located on the wheel side, it does not record this disturbance. Therefore, two probes are required to measure Runout and Roundness of a roll with periodic motion.