In this paper, we present the results of an experimental investigation on squeal noise emitted by a disc brake for railway applications. The measurement, that show in an evident manner the onset of instability forms during the braking phase were made on a test-rig in real scale on which we measured by means of a sound intensity probe the noise emitted by the disc brake. By using a Fast Fourier Transform (FFT) we identified the strongest detected frequencies. The aim of this paper is to analyse such phenomena by conducting a Finite Element Analysis (FEA) of the 3D CAD model of the disk modelled in Ansys Workbench FEM software, in order to, better understand the path that leads a stable system to unstable behaviour. The system analysed is composed of a steel disk and four pads made of an array of cylinders made of frictional material. Such pad system has been designed in order to simplify the simulation, assuming that it acts on the disk surface just in some points. The numerical results agree with the experimental ones.