An apparatus for smoothing an inner toothing and/or an outer toothing of a component part. At least two radially adjustable smoothing gears, which engage in the inner toothing and/or outer toothing, are rotatably arranged inside the inner toothing and/or outside of the outer toothing. During smoothing, the component part is not firmly clamped but rather only rests loosely on a support. A thrust ring is provided at least at one of the smoothing gears for limiting axial movements of the component part, which occur during smoothing.