Proceedings of the 3 rd International Conference on Manufacturing Engineering (ICMEN), 1-3 October 2008, Chalkidiki, Greece Edited by Prof. K.-D. Bouzakis, Director of the Laboratory for Machine Tools and Manufacturing Engineering (ΕΕΔΜ), Aristoteles University of Thessaloniki and of the Fraunhofer Project Center Coatings in Manufacturing (PCCM), a joint initiative by Fraunhofer-Gesellschaft and Centre for Research and Technology Hellas, Published by: ΕΕΔΜ and PCCM 107 ANALYSIS OF MECHANICAL LOADS AND RESULTANT EFFECTS WHEN MACHINING REINFORCED LIGHTWEIGHT STRUCTURES D. Biermann 1,a , A. Zabel 1,b , T. Engbert 1,c , T. Upmeier 1,d 1. Institute of Machining Technology (ISF), TU Dortmund, Baroper Str. 301, 44227 Dortmund, Germany, a biermann@isf.de, b zabel@isf.de, c engbert@isf.de, d upmeier@isf.de ABSTRACT Lightweight construction elements are designed to increase the energy efficiency of vehicles. Composite extrusions with aluminum-matrix combine the high ductility of the matrix material with the strength of continuous reinforcing elements. The con- trast of ductile matrix and hard reinforcement appears to be a challenge in machin- ing. In this article, the influence of mechanical loads on continuously reinforced thin- walled structures and tools during the machining of joining zones is presented. The experiments comprise end milling, circular milling of holes and threading. The analy- ses of the occurring forces show, that the reinforcing element and its orientation relative to the tool can influence the maximum forces decisively. High quality ma- chining results can still be obtained by choosing suitable machining strategies. KEYWORDS: Lightweight construction, Composite, Cutting, Milling, Threading 1. INTRODUCTION Economic and environmental aspects are getting more and more in focus of the modern auto- mobile industry. The designer has to consider the costs as well as the requirements of the cus- tomer for more comfort and a higher standard of security. These, partly controversial, specifica- tions lead to the research and development of new materials in lightweight construction. Be- sides, lightweight construction not only means the use of light and thin materials, rather it is more a whole concept including material selection and manufacturing methods. The aim is to have operational high quality products with a reduced mass compared to conventional compo- nents. /1, 2/ Today, it is possible to reinforce profiles as per requirement by an extended extrusion process. It allows producing light framework structures with an excellent resistance against defined ex- ternal loads. The field of application extends from single components to complete structures. The extended extrusion process makes it possible to position the reinforcement almost freely in the cross-section of a profile to achieve a specific reinforcement. /3/ For the assembly of light frameworks, it is essential to join the profiles. Depending on the decision which joining process is used, the demands for preparing the joining zone vary. Rolling-in operations and electromag- netic forming processes require a certain clearance between the joining components, whereas the reinforcement has to be integrated into the thread flank, when a threading process is used. The contrast between ductile matrix and hard reinforcing elements leads to fluctuating loads on the cutting edge, which can affect tool wear as well as the quality of the machined surface. Es-