ORIGINAL ARTICLE Effect of generatrix profile on single-point incremental forming parameters Mariem Dakhli 1 & Atef Boulila 2 & Zoubeir Tourki 1 Received: 16 January 2017 /Accepted: 31 May 2017 # Springer-Verlag London 2017 Abstract The single-point incremental forming is one of two modes of the incremental sheet forming process. It is the most used in the manufacture of parts for small series and prototypes in various sectors such as aeronautics, bio- medical field, and art pieces. In this work, two geometries of parts are investigated at the same process parameters (rotation speed, feed rate, step increment, sheet thickness, and tool diameter). The experimental tests are made with a CNC spinner milling machine. The blank sheet of mild steel is formed by means of a hemispherical tool with a 10-mm diameter. The forming tool follows the desired spiral path that is determined by a CAD model. The main objective of this paper is to study the effects of the gen- eratrix profile for two shapes of a truncated cone (straight and circular generatrix) on forming forces, thickness dis- tribution, shape accuracy, and surface roughness of the formed shape. Besides, a coefficient of shape is intro- duced from experimental and analytical vertical forces. The experimental results show that a better roughness surface quality is obtained in forming a straight generatrix and that a more uniform thickness distribution of the blank is obtained after thinning and shaping a circular generatrix. In order to examine the geometric accuracy of the parts, a Next Engine 3D scanner is used to rebuild the developed surfaces again and to make a comparison between the programmed and scanned profiles. Keywords Single-point incremental forming . Generatrix . 3D scanning . Thickness . Shape accuracy . Roughness 1 Introduction The most forming process reputed for obtaining parts with complex geometries and optimizing a loss of material is the incremental sheet forming. Generally, this process, which firstly appeared in the work of Leszak in 1967 [1], is based on the plastic deformation of a thin sheet metal (less than or equal to 3 mm) using an inexpensive hemispherical tool with- out dies. Later, a lot of authors developed this process because of the appearance and development of the CNC machining and CAD/CAM software [2–4]. The forming tool is controlled by a CNC milling machine and it follows the path generated by the Catia software. The tool then pushes the sheet metal incrementally, which decreases the thickness of the part. The incremental sheet forming is divided in two modes: single-point incremental forming (SPIF) and two-point incre- mental forming (TPIF). The main difference between these two processes is the number of contact points between the sheet and the tool. In the SPIF, the forming tool is in contact at only one point with the sheet. The blank sheet is mounted on the die and fixed by a blank holder around its edges [5]. In this paper, we involve our research in the SPIF process. However, the main drawbacks of this process are the high production time and the limit of forming the right angles [6]. On the other hand, it presents a lot of advantages such as the possibility to manufac- ture complex forms of sheet metal parts in a rapid and economic way without expensive dies and long setup times. Numerous researches have been conducted to study the ef- fect of geometries of forming tools. For that, some authors have tested the semi-spherical tool head with a radius ranged be- tween 5 and 25 mm [7]. Moreover, others have used a * Mariem Dakhli Mariem.Dakhli@eniso.rnu.tn 1 Mechanical Laboratory of Sousse, National Engineering School of Sousse, University of Sousse, BP 264, Sousse Erriadh, Tunisia 2 National Institute of Applied Science and Technology, Centre Urbain Nord, University of Carthage, BP 676 - 1080, Tunis Cedex, Tunisia Int J Adv Manuf Technol DOI 10.1007/s00170-017-0598-1