ORIGINAL ARTICLE Effect of machining-induced residual stress on the distortion of thin-walled parts Soroush Masoudi & Saeid Amini & Ehsan Saeidi & Hamdollah Eslami-Chalander Received: 27 January 2014 /Accepted: 14 August 2014 /Published online: 5 September 2014 # Springer-Verlag London 2014 Abstract One of the main problems in the machining of thin- walled parts made of high-strength aluminum alloys is distor- tion and dimensional instability after machining, which leads to an increase in scraped parts and the cost of production. In general, distortion and dimensional instability in machined parts made of aluminum alloy is a function of the residual stresses. In this article, the correlation between machining- induced residual stresses and distortion in a thin-walled work pieces is investigated. Several experiments are carried out under different machining conditions using two carbide and polycrystalline diamond (PCD) tools on a thin-walled cylinder made of AL7075-T6 alloy. Rates of variations in geometrical tolerances and distortion for all work pieces are measured. To study the effect of mechanical and thermal loads on the residual stresses and distortion, the machining force and tem- perature of cutting area are measured. Finally, the correlation between the residual stress and distortion is studied by mea- surement of residual stress on some work pieces. Similarly, in order to investigate the effect of work pieces thickness on distortion, several tests are carried out on three work pieces with different thicknesses. The results indicate that the force and temperature have direct effect on the residual stresses and distortion in the thin-walled parts. Keywords Residual stress . Distortion . Machining . Thin-walled parts . AL7075 Alloy 1 Introduction In aerospace and automotive industries, the design and use of thin-walled monolithic parts made of aluminum alloys with a high strength to weight ratio is widely increased since reduc- tion in the overall weight of the components, reduction in fuel consumption, and compaction in size are valued highly. In the machining of thin-walled parts, up to 98 % of the volume of the raw material is removed [1]. One of the main problems in the machining of thin-walled parts made of high-strength aluminum alloys is distortion and dimensional instability after machining, which leads to an increase in scraped parts and the cost of production. According to a study conducted in Boeing Company with respect to the information on manufacturing of four different airplanes, the costs of waste materials and the rework related to distortion of the machined parts is estimated over 290B USD [2]. Distortion in parts can range from a few micrometers in small pieces to several centimeters in large pieces. In general, distortion and dimensional instability in machined parts made of aluminum alloy is a function of the residual stresses in the material as well as machining-induced residual stresses [3]. The low stiffness and high resilience of the thin-walled parts with exertion of severe mechanical forces induced by machining and clamping intensify the deformation and distortion in such work pieces [4]. Quenching is used in heat treatment of aluminum alloys in order to achieve the given mechanical properties. This process is considered as the paramount factor in creating residual stress in materials [5]. With immersion of a part with high S. Masoudi Department of Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran S. Amini (*) Manufacturing Group, Department of Mechanical Engineering, University of Kashan, Kashan, Iran e-mail: amini.s@kashanu.ac.ir E. Saeidi Department of Mechanical Engineering, Yazd University, Yazd, Iran H. Eslami-Chalander Institute of Joining and Welding, Technical University of Braunschweig, Braunschweig, Germany Int J Adv Manuf Technol (2015) 76:597–608 DOI 10.1007/s00170-014-6281-x