An electric machine comprising: a shaft, which is mounted so as to rotate around a central rotation axis; a rotor with permanent magnets, which is fitted to the shaft so as to rotate together with the shaft; a stator with a tubular, cylindrical shape, which is arranged around the rotor so as to enclose, on the inside, the rotor and has a magnetic core, which consists of a series of laminations made of a ferromagnetic material and is longitudinally crossed by a plurality of stator slots; and a stator winding comprising a plurality of copper rigid bars, which are inserted in corresponding stator slots and are covered, on the outside, with an insulating coating; wherein each stator slot is completely free from an insulating element interposed between the ferromagnetic material making up the laminations of the magnetic core and the corresponding bars, so that an outer surface of the corresponding bars is in direct contact with an inner surface of the stator slot made of the ferromagnetic material of the stator slot; the electric machine is characterized in that: the insulating coating which covers on the outside each bar has an inner layer that is in direct contact with the copper and an outer layer that is arranged above the inner layer and is in direct contact with the ferromagnetic material making up the laminations of the magnetic core; and the inner layer consists of a first material and the outer layer consists of a second material that differs from the first material, is mechanically stronger than the first material to mechanically protect the inner layer from rubbing against the inner surface of the stator slot, and is electrically less insulating than the first material, so that the inner layer essentially has the function of ensuring electric insulation. a shaft, which is mounted so as to rotate around a central rotation axis; a rotor with permanent magnets, which is fitted to the shaft so as to rotate together with the shaft; a stator with a tubular, cylindrical shape, which is arranged around the rotor so as to enclose, on the inside, the rotor and has a magnetic core, which consists of a series of laminations made of a ferromagnetic material and is longitudinally crossed by a plurality of stator slots; and a stator winding comprising a plurality of copper rigid bars, which are inserted in corresponding stator slots and are covered, on the outside, with an insulating coating; wherein each stator slot is completely free from an insulating element interposed between the ferromagnetic material making up the laminations of the magnetic core and the corresponding bars, so that an outer surface of the corresponding bars is in direct contact with an inner surface of the stator slot made of the ferromagnetic material of the stator slot; the electric machine is characterized in that: the insulating coating which covers on the outside each bar has an inner layer that is in direct contact with the copper and an outer layer that is arranged above the inner layer and is in direct contact with the ferromagnetic material making up the laminations of the magnetic core; and the inner layer consists of a first material and the outer layer consists of a second material that differs from the first material, is mechanically stronger than the first material to mechanically protect the inner layer from rubbing against the inner surface of the stator slot, and is electrically less insulating than the first material, so that the inner layer essentially has the function of ensuring electric insulation. the insulating coating which covers on the outside each bar has an inner layer that is in direct contact with the copper and an outer layer that is arranged above the inner layer and is in direct contact with the ferromagnetic material making up the laminations of the magnetic core; and the inner layer consists of a first material and the outer layer consists of a second material that differs from the first material, is mechanically stronger than the first material to mechanically protect the inner layer from rubbing against the inner surface of the stator slot, and is electrically less insulating than the first material, so that the inner layer essentially has the function of ensuring electric insulation.