Balancing is a speed-and-geometry decision, not a label that should be copied blindly from one pulley catalogue to every application. An unbalanced pulley can add vibration and bearing load; the acceptable residual unbalance depends on the rotating assembly and operating speed.
Static and dynamic balance
Static balancing addresses a heavy spot that makes a stationary rotor turn until the heavy side is low. Dynamic balancing also considers couple unbalance across the rotor width and is carried out while rotating. Wider, larger or faster pulleys are more likely to need a two-plane dynamic balance review.
What G6.3 means
G6.3 is a commonly specified balance-quality grade for general industrial rotors. It should be stated together with operating speed and the part configuration being balanced. If your machine drawing calls for another grade, that requirement controls.
What to put on the RFQ
Include pulley model, finished bore/bush, operating rpm and the required balance grade or vibration criterion. If no balance requirement is defined, state the speed and application so the quotation can identify whether standard production balance is sufficient or a special operation is needed.
Need help matching a pulley? Email [email protected] with the belt marking, shaft diameter and pulley measurements.