Full definition
The process of ensuring uniform mass distribution in a rotating pulley to minimize vibration and bearing loads during operation. Unbalance creates a centrifugal force proportional to mass eccentricity and the square of rotational speed, producing 1x RPM vibration. Balance quality grades per ISO 1940-1: G16 (general industrial, fans, flywheels), G6.3 (standard electric motors, pumps, general machinery — most common industrial requirement), G2.5 (medium precision, turbochargers, machine-tool drives), G1.0 (high precision, grinding spindles). Permissible residual unbalance: U_per = (G × m) / ω, where m is rotor mass and ω is angular velocity. Balancing is critical for pulleys operating above 1,500 RPM or with diameters >500 mm. Methods: static (single-plane) for narrow pulleys, dynamic (two-plane) for wide pulleys. Equipment: Schenck, IRD, Hofmann balancing machines.