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It depends on the roll position. Calender and press rolls in high-speed machines (>1000 m/min) benefit from G2.5. Dryer cylinders typically use G6.3. Guide and felt rolls use G6.3. The general rule: the closer the roll is to the paper web forming and finishing, the tighter the balance requirement.

Paper machine speeds are universally specified as surface (line) speed in m/min, not as RPM. Different diameter rolls all run at the same surface speed (the machine speed), but at different RPMs. This calculator converts for you.

Steam-heated dryer cylinders contain condensate that redistributes based on speed and siphon operation. At low speeds, condensate pools at the bottom (cascading regime) causing vibration. At higher speeds, it forms a uniform ring (rimming regime). Transition between regimes during ramp-up can cause temporary high vibration. Allow the machine to reach steady state before drawing balance conclusions.

Yes, in-situ (field) balancing is common for paper machine rolls, especially for dryer cylinders that are difficult to remove. Use vibration sensors on the bearing housings and a keyphasor on the shaft. Two-plane balancing is typically needed for long rolls (L/D > 0.5). Correction masses are added at dedicated balance weight locations on the roll heads.

Common causes include: cover wear or damage (rubber/polyurethane), corrosion pitting on the shell, condensate system issues in dryer cylinders, thermal distortion, buildup of paper fiber or coating material, and cracking of the shell or heads. Regular vibration monitoring catches these issues early.

Very critical. Unbalance-induced vibration causes barring (regularly spaced marks) on calender and press rolls, uneven moisture profiles in press and dryer sections, and reel defects (corrugation, starring). Balance quality directly impacts paper surface quality and printability.