ORIGINAL ARTICLE Micro-extrusion of ultra-fine grained aluminium Andrzej Rosochowski & Wojciech Presz & Lech Olejnik & Maria Richert Received: 6 February 2006 / Accepted: 17 January 2007 / Published online: 16 February 2007 # Springer-Verlag London Limited 2007 Abstract Microforming of normal, coarse grain (CG) metals leads to scale problems which originate from the fact that the grain size becomes comparable to the part size. A possible way of dealing with these problems is replacing CG metals with ultra-fine grained (UFG) metals. UFG metals can be produced in bulk by severe plastic deforma- tion (SPD). This paper describes using UFG aluminium 1070 for preliminary trials of micro extrusion of a cylindrical cup. The process of producing bulk UFG aluminium by SPD is explained and the material obtained characterised. The preparation of micro billets for the extrusion operation is discussed. Backward extrusion is carried out for two types of material, CG and UFG. This enables a comparison of the material behaviour and product characteristics. Using UFG aluminium in microforming results in more uniform products with improved mechanical properties. Keywords Micro-extrusion . Microforming . Severe plastic deformation . Ultra-fine grained metals 1 Introduction Microforming of metals is one of the emerging technolo- gies, which increases the palette of micro components available. As with many micro manufacturing techniques, scaling down the existing technology is problematic. One aspect in particular has drawn attention for many years. It is the grain size of the material formed which becomes comparable with the size of micro component or the size of some of its geometrical features. Metal forming of a few grains rather than a polycrystalline material leads to an unusual material response, increased friction and reduced repeatability (scatter of results). These, and other techno- logical problems, were reviewed by Geiger et al. [1] and Engel and Eckstein [2]. The focus of some publications was explicitly on the grain size effects. For example, Raulea et al. [3] carried out experiments on pure aluminium using tensile specimens with different thicknesses and a given grain size as well as Int J Adv Manuf Technol (2007) 33:137–146 DOI 10.1007/s00170-007-0955-6 A. Rosochowski (*) Design, Manufacture and Engineering Management, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UK e-mail: a.rosochowski@strath.ac.uk URL: www.dmem.strath.ac.uk W. Presz : L. Olejnik Institute of Materials Processing, Warsaw University of Technology, 85 Narbutta Street, Warsaw 02-524, Poland W. Presz e-mail: w.presz@wip.pw.edu.pl URL: www.wip.pw.edu.pl L. Olejnik e-mail: l.olejnik@wip.pw.edu.pl URL: www.wip.pw.edu.pl M. Richert Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland e-mail: mrichert@uci.agh.edu.pl URL: www.uci.agh.edu.pl