Recent Advances in Mechanical Micromachining This paper reviews recent developments and future requirements in micromachining, focusing on the machining process. Micromachining involves creating precise two and three-dimensional workpieces with dimensions ranging from a few tens of nanometers to several millimeters using defined geometry cutting tools. The review covers process physics, including material and microstructural effects, machine tools, tooling and sensing, workpiece and design issues, software and simulation tools, and other issues such as surface and edge finish, and outlook for future developments. Micromachining is strictly defined as mechanical cutting of features with tool engagement less than 1 mm using geometrically defined cutting edges. The paper emphasizes the present state and future requirements for increased understanding of the fundamental process physics, modeling efforts, experimental validation, and machine tool development. Research on manufacturing in general and mechanical micromachining in particular must be viewed in the context of various "scales" beyond part dimensions, including societal, sensing and process intelligence, reconfigurability, modeling, and machine tools. Micromachining is influenced by size effects, which can change the machining process when the ratio of part size to tool dimension becomes small. The paper discusses the effects of size on micromachining, including the role of tool edge geometry, grain size and orientation, and the transition from cutting to plowing as the depth of cut decreases. It also covers anisotropic machining, where the material microstructure plays a significant role, and the effects of crystallographic orientation on surface and subsurface crack generation. The paper also discusses ductile mode machining, where brittle materials can be machined in a ductile fashion with good surface finish. It covers chip formation and built-up-edge issues, as well as surface and edge finish problems in micromachining. The paper highlights the importance of modeling in micromachining, including finite element modeling (FEM) and molecular dynamics (MD) simulations, and discusses multiscale modeling techniques that combine FEM and MD to overcome the limitations of each method. The paper concludes with a discussion of workpiece and design issues in micromachining, including micromolding and the importance of tooling in micromachining for other micro-mass production technologies. The paper emphasizes the need for further research in this field to improve the understanding of micromachining and to develop better tools and processes for micromachining.Recent Advances in Mechanical Micromachining This paper reviews recent developments and future requirements in micromachining, focusing on the machining process. Micromachining involves creating precise two and three-dimensional workpieces with dimensions ranging from a few tens of nanometers to several millimeters using defined geometry cutting tools. The review covers process physics, including material and microstructural effects, machine tools, tooling and sensing, workpiece and design issues, software and simulation tools, and other issues such as surface and edge finish, and outlook for future developments. Micromachining is strictly defined as mechanical cutting of features with tool engagement less than 1 mm using geometrically defined cutting edges. The paper emphasizes the present state and future requirements for increased understanding of the fundamental process physics, modeling efforts, experimental validation, and machine tool development. Research on manufacturing in general and mechanical micromachining in particular must be viewed in the context of various "scales" beyond part dimensions, including societal, sensing and process intelligence, reconfigurability, modeling, and machine tools. Micromachining is influenced by size effects, which can change the machining process when the ratio of part size to tool dimension becomes small. The paper discusses the effects of size on micromachining, including the role of tool edge geometry, grain size and orientation, and the transition from cutting to plowing as the depth of cut decreases. It also covers anisotropic machining, where the material microstructure plays a significant role, and the effects of crystallographic orientation on surface and subsurface crack generation. The paper also discusses ductile mode machining, where brittle materials can be machined in a ductile fashion with good surface finish. It covers chip formation and built-up-edge issues, as well as surface and edge finish problems in micromachining. The paper highlights the importance of modeling in micromachining, including finite element modeling (FEM) and molecular dynamics (MD) simulations, and discusses multiscale modeling techniques that combine FEM and MD to overcome the limitations of each method. The paper concludes with a discussion of workpiece and design issues in micromachining, including micromolding and the importance of tooling in micromachining for other micro-mass production technologies. The paper emphasizes the need for further research in this field to improve the understanding of micromachining and to develop better tools and processes for micromachining.