CALCULATION OF THE FRACTAL DIMENSIONS OF MACHINED SURFACE PROFILES

The optimal method calculating the fractal dimension of a machined sur face profile is discussed in this paper. Through the analysis of the r esults calculated by use of the Weiestrass-Mandelbrot fractal function with known fractal dimensions, the variation method is found to be th e best one for calculating the fractal dimensions of the surface profi les among the power spectrum method, the cover method and the rectangu lar cell counting method. By this method, the fractal dimensions of th e surface profiles machined by turning, electrical discharge machining and grinding are evaluated. Furthermore, the relation between the fra ctal dimensions and the machining conditions are also investigated. In the case of turning, the fractal dimensions of surface profiles decre ase with the change of the feed rate whereas the nose radius. The frac tal dimensions of the electrical discharge machining surface profiles hardly vary with an increase of the peak discharge currents and the pu lse durations. The fractal dimensions of the surface profiles machined by grinding do not change with the grain sizes of grinding wheels.