Acoustic Performance of Glass Wool Insulation for Noise Reduction in Industrial Gearboxes

Abstract

This study examines the effectiveness of glass wool insulation in reducing noise levels in an industrial helical gearbox, which initially produced noise levels of 85.8 dB at the input shaft (location A), 83.8 dB at the output shaft (location B), and 90.8 dB at the center (Locations C). The goal was to achieve at least a 5 dB reduction at Location C to comply with the 85 dB noise exposure limits. Glass wool, with a high sound absorption coefficient of 0.8, was installed as an acoustic enclosure around the gearbox, and sound pressure levels (SPL) were measured at these three locations. After recording baseline measurements without insulation, tests were conducted with 1.5-inch thick glass wool insulation (48 kg/m³ density). The gearbox operated at 7552 rpm, with noise measurements taken over 4 hours, including at the critical speed of 8500 rpm. The results showed reduced noise levels of 82.9 dB, 79.7 dB, and 81.9 dB at Locations A, B, and C, respectively, effectively lowering noise and meeting the target for Location C. This confirms that 1.5-inch glass wool insulation is optimal for reducing noise in industrial gearboxes.