Abstract: The wear condition of a milling tool is determined by detecting vibrations of the milling tool and a metal workpiece and generating wavelet coefficients which are utilized to evaluate the wear condition of the workpiece. The vibrations are detected at several locations along the metal workpiece or upon a different workpiece under comparable conditions and evaluating workpiece wear on the basis of changes in wear condition parameters at different locations and/or comparable cutting engagement between the milling tool and similar or different workpieces.