1997 Fiscal Year Final Research Report Summary

Study on Biomachining of Metals Using Bacteria

Research Project

Project/Area Number	08455077
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	機械工作・生産工学
Research Institution	OKAYAMA UNIVERSITY
Principal Investigator	UNO Yoshiyuki Okayama Univ., Engineering, Professor, 工学部, 教授 (20029341)
Co-Investigator(Kenkyū-buntansha)	OKADA Akira Okayama Univ., Engineering, Research Assistant, 工学部, 助手 (60263612)
Project Period (FY)	1996 – 1997
Keywords	biomachining / bacteria / Thiobacillus Ferrooxidans / culture / machining of metals / field assisted / side etch / jet injection
Research Abstract	This study has done for 2 years from Apr.1996 to Mar.1997 in order to machine metals finely using Thiobacillus Ferroxidans which is a kind of chemolithotrophic bacteria. The details is as follows. In the conventional machining, physical or chemical energy is concentrated to the designated point, then the pointed material is removed, deformed or added. However in the biomachining proposed in this study, biological energy was used for the removal of metals. In the first year, the method of pure culture of bacteria was firstly established and the machining experiment was done in the cultured fluid. It was cleared that this bacteria hadbasically the ability of machining of metals and the removal stock increased linearly with the machining time. Furthermore, the removal stock became twice when the low voltage was added to the workpiece. In the second year, the problem of side etch which was consideted to be a big touble in practical use was experimentally investigated. As a result, etch factor which is the ratio of depth to width of groove was about 2, which indicates the depth of superior in metal removal to the width of groove. Moreover, the jet injection of cultured fluid towards the workpiece was tried. The experimental results pointed out that the removal rate increased by a large margin and the side etch decreased. From now on, further investigations of method of effective designation of removal point and the development of machining device are needed.