Surface Roughness and Material Removal Rate in Machining Using Microorganisms

The use of bacteria as a tool for machining, also known as biomachining, is a novel material removal process. This study characterizes the surface changes and relates the material removal rate to quantified bacterial concentrations resulting from machining of pure polycrystalline Cu using the bacterium Acidithiobacillus ferrooxidans. Cu blocks, polished to four levels of surface roughness, were utilized to examine the surface effects of bacterial machining. The mass change in Cu foil was measured to find the material removal rate. The most probable number method, a statistical enumeration technique, was applied to estimate bacterial concentrations. Scanning electron microscope (SEM) micrographs demonstrate that bacterial machining is anisotropic, and roughness measurements of the polycrystalline Cu samples showed a deterioration of $Ra$ values of $1.5-2.5μm$⁠. Finally, suggestions for future work are presented that could potentially ameliorate current process problems.