On the nature of idling noise of circular saw blades

Simulation and analysis of aerodynamics for high speed face milling cutters

“…To accurately calculate the aerodynamic noise contribution due to the cutter alone, the sound spectrum plots for the total noise and noise due to spindle rotation were obtained, the difference between total noise and spindle noise was around 1.0 dB for all cases. The comparisons of the sound pressure level calculated by the model and the experimental observations of aerodynamics noise due to cutter rotating at the various tip velocities are shown in Figure 4 (v 0 is the reference velocity (1.0 m/s) and v is the tip velocity [3]). The model predicted SPL is, on average, roughly 2.0 dB less than the experimentally observed SPL.…”

“…Second, the major source of aerodynamic noise for the inserted face milling cutters rotating at high speeds is predominant due to dipole sources and the effect of quadrupole noise source is found to be negligible. Third, the noise generated at far-field is of interest, namely, the observation point should be placed at a distance of at least ten times the cutter radius [3,6] (preliminary experiments showed that most of the important noise generating frequencies were between 550 Hz and 3000 Hz, the major noise wavelength was between 0.113 m and 0.62 m according to the relationship of sound speed, wavelength and noise frequencies, so the far-field assumption is valid). This result is…”

“…Therefore, soundproof shield was used to reduce the reflectivity as well as exclude outside noise. Noise was measured using a TES 1350A, the microphone should be placed at a distance of at least ten times the cutter radius [3,6] to measure the noise in far field. Hence, for this experiment the microphone was placed at a distance of 0.7 m from the center of the cutter in the horizontal plane of the cutter as shown in Figure 3.…”

“…Idling noise consists of aerodynamic noise, noise due to cutter vibration caused by flow of air around the cutter teeth [3] and spindle motor drive noise. Sampath et al [4] found that the dipole sources were the major sources and the effect of quadrupole sources on the sound pressure level appeared to be negligible.…”

Numerical Analysis of Aeroacoustic Noise for High-Speed Face Milling Cutters in Three Dimensional Unsteady Flow Fields

“…The aeroacoustic noise from face milling cutters is usually caused by the 3D unsteady flow around the cutters, namely, by the air flow fluctuation as a result of the interaction between air flow and cutter surface [6]. Sampath et al [2] experimentally determined the characteristics of sound sources in face milling, and found that the dipole-like is the major source of aerodynamic noise for milling cutters rotating at high speeds and the effect of quadrupole sources on the sound pressure level appears to be negligible.…”