Evaluation of the wavelet transform method for machined surface topography 2: Fractal characteristic analysis

The wavelet transform method is a new method for characterising the roughness profiles of machined surfaces. Based on the Weierstrass-Mandelbrot function and the Majumdar-Bhushan function with known fractal dimension, the wavelet transform method accurately calculates the fractal dimension. The fractal characteristics of test surfaces for pool boiling experiments are evaluated by the Wavelet transform method. Using general machining methods, these surfaces were prepared by rolling, hand and machine polishing copper and stainless steel. The results indicate that the wavelet transform method is more effective than seven other methods for calculating the fractal dimensions of roughness profiles. The topography of the surfaces is shown to be anisotropic. Although this method is developed to describe the test surfaces for boiling experiments, it may be more generally applicable in the field of tribology.