4M Knowledge base - papers

S. Geißdörfer (a), A. Rosochowski (b), L. Olejnik (c), U. Engel (a)

(a) Chair of Manufacturing Technology, University of Erlangen-Nuremberg, Egerlandstrasse 11, 91058 Erlangen, Germany
(b) Department of Design, Manufacture and Engineering Management, University of Strathclyde, 75 Montrose Street, Glasgow, United Kingdom, G1 1XJ
(c) Institute of Materials Processing, Warsaw University of Technology, 85 Narbutta Street, 02-524 Warsaw, Poland

Abstract

Because of the well known virtues of low cost and high productivity, metal forming technology is well suited for mass production of metal micro-components. However, scaling down traditional metal forming processes proves to be problematic because, among other factors, the relatively coarse grain (CG) structure of micro-billets leads to nonuniform material flow and lack of repeatability during microforming. The aim of the presented study is to investigate a possibility of using an ultrafine grained (UFG) copper for micro-extrusion. The UFG version of Cu is produced by severe plastic deformation at room temperature using 4 and 8 passes of equal channel angular pressing (ECAP). The microstructure and compression properties of the UFG copper are investigated. For visualisation purposes, the microforming process of backward extrusion is carried out at room temperature using half cylindrical billets and transparent tools. The extrusion results, for billets subjected to 4 and 8 passes of ECAP, are compared in terms of the extrusion force, grain flow, shape representation and surface quality and show clearly that applying ultrafine grained material to microforming processes reduces scaling effects.

Micro-extrusion of ultra-fine grain aluminium
A. Rosochowski (a), W. Presz (b), L. Olejnik (b), M. Richert (c)
a Design, Manufacture and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, UK
b Institute of Materials Processing, Warsaw University of Technology, 02-524 Warsaw, Poland
c Faculty of Non-Ferrous Metals, AGH University of Science and Technology, 30-059 Krakow, Poland

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 grain (UFG) metals. UFG metals can be produced in bulk by severe plastic deformation (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.