Study on material removal mechanism and improvement of machining speed in biomachining

Biomachining is a novel machining technology and is different from the traditional physical and chemical machining methods, in which biological energy of bacteria is used as a main energy source for machining process. Previous report has made it clear that the machining speed becomes higher under proper shaking rate and temperature, higher efficient process can be achieved under electric field, and so on. However, the material removal mechanism has not yet been clarified sufficiently. In this report, the material removal mechanism in biomachining was discussed, by comparing the material removal rate for iron and copper. The experimental results indicate that, in the material removal, bacteria acts on the material not only directly, but also indirectly, that is to say, bacteria promotes the change from Fe²⁺ion to Fe ³⁺ion which has powerful oxidizing effects and makes the material dissolved. Furthermore, the effects of cultured fluid flow on machining characteristic were investigated. As a result, the cultured fluid flow significantly influences the machining rate, and high efficient machining can be achieved by jetting out the cultured fluid from nozzle with high flow rate.