When analysing the sound pressure level depending on the
stiffness ofthe part, it was observed that for stiffness ratios of1 and higher, the sound pressure level was not significantly influenced,
being 92 dBA (inside). However, when the stiffness ratio was lower
than 1, the sound pressure level increased dramatically reaching
values of 122 dBA (inside) and 102 dBA (outside). This is due to the
fact that the milling operation becomes unstable with a flexible part
causing the chatter to become dominant. Thus the stiffness of the
part can increase sound pressure level by more than 30 dBA (sound
pressure 31 times higher) compared to a rigid configuration