J. Mater. Sci. Technol., 2012, 28(8), 673–685. • Invited Review State of the Art on Micromilling of Materials, a Review M.A.Cˆamara 1) , J.C. Campos Rubio 1) ,A.M.Abr˜ao 1) and J.P. Davim 2)† 1) Department of Mechanical Engineering, Universidade Federal de Minas Gerais, Av. Antˆonio Carlos, 6627–Pampulha, Belo Horizonte MG, CEP: 31.270-901, Brazil 2) Department of Mechanical Engineering, University of Aveiro, Campus Universit´ario de Santiago, 3810-193, Aveiro, Portugal [Manuscript received July 22, 2012] J. Paulo Davim received his Ph.D. degree in Mechanical Engineering from the University of Porto in 1997 and the Aggregation from the University of Coimbra in 2005. Currently, he is an Aggregate Professor at the Department of Mechanical Engineering of the University of Aveiro and the Head of MACTRIB-Machining and Tribology Research Group. He has 25 years of teaching and research ex- perience in manufacturing, materials and mechanical engineering with special emphasis on Machining & Tribology. Currently, he has also interest in sus- tainable manufacturing and industrial engineering. He is the editor in chief of six international journals, guest editor of journals, books editor, book series editor and scientific advisory for many international journals and conferences. Presently, he is an editorial board member of 20 international journals and acts as a reviewer for more than 70 prestigious ISI Web of Science journals. In addition, he has also published as an author and co-author more than 30 book chapters and 350 articles in journals and conferences (more than 170 articles in ISI Web of Science, h-index 21). The trend towards miniaturization has increased dramatically over the last decade, especially within the fields concerned with bioengineering, microelectronics, and aerospace. Micromilling is among the principal manu- facturing processes which have allowed the development of components possessing micrometric dimensions, being used to the manufacture of both forming tools and the final product. The aim of this work is to present the principal aspects related to this technology, with emphasis on the work material requirements, tool ma- terials and geometry, cutting forces and temperature, quality of the finished product, process modelling and monitoring and machine tool requirements. It can be noticed that size effect possesses a relevant role with regard to the selection of both work material (grain size) and tooling (edge radius). Low forces and temper- ature are recorded during micromilling, however, the specific cutting force may reach high values because of the ploughing effect observed as the uncut chip thickness is reduced. Finally, burr formation is the principal concern with regard to the quality of the finished part. KEY WORDS: Micro-milling; Micromachining; Size effect; Miniaturization 1. Introduction In general, micromachining is defined based on the dimensions of the cutting tool, which should lie within the range from 1 to 1000 μm, however, the most relevant aspect concerned with the scope of this † Corresponding author. Prof., Ph.D.; Tel.: +351 234 370953; E-mail address: pdavim@ua.pt (J.P. Davim). group of operations resides in the fact that the un- cut chip thickness and work material grain size pos- sess dimensions comparable to the cutting edge ra- dius. Consequently, the traditional approaches used to describe the phenomena involved in conventional (or macro) machining do not apply in this case simply by downscaling. Micromilling allows the production of three dimensional components in a range of mate- rials such as metallic alloys, ceramics and polymeric