Additive manufacturing of H-13 inserts for optimal extrusion die cooling Lorenzo Donati 1 , Barbara Reggiani 2 , Riccardo Pelaccia 2 , Giuseppe Valli 1 , Ivan Todaro 1 , Rosario Squatrito 1 , Luca Tomesani 1 , Tommaso Pinter 3 , Enea Mainetti 4 , Yoram Rami 5 1 University of Bologna, Department of Industrial Engineering (DIN), giuseppe.valli2@unibo.it; ivan.todaro@unibo.it; l.donati@unibo.it ; luca.tomesani@unibo.it 2 University of Modena and Reggio Emilia, Department of Sciences and Methods for Engineering, riccardo.pelaccia@unimore.it; barbara.reggiani@unimore.it 3 Almax-Mori S.r.l., Via Matteotti 13, Mori (TN) 38065, Italy, tommaso.pinter@almax-mori.it 4 A.t.i.e. Uno Informatica S.r.l., via Macon 30, 23900 Lecco, Italy, enea.mainetti@unoi.it 5 S.h.l. ALUBIN, Kiryat Bialik (Il), yoram@alubin.com ABSTRACT The hot extrusion process is a widespread manufacturing technology selected to produce sound profiles of almost any complex section. Even assumed the consolidated state of the process, however many process related aspects need still to be completely solved such as those related to the high temperatures involved. Many defects can indeed arise consequently to the heat generated for the work spent to overcome friction at the tool/workpiece interfaces and to plastically deform the material as well as to the set pre-heating temperatures. These defects (hot cracks, tearings, pick-up, ..) can affects both the quality of the extrudate and the achievable productivity thus reducing the overall process efficiency. A solution adopted at industrial level is the use of liquid nitrogen cooling supplied by means of a channel manufactured on the mating face of the die with the backer. However, this has the main drawback to remove heat far from the regions where the highest temperature are reached, the bearing zones. In this context, the additive manufacturing technologies offer a valid turning key allowing integrating in the dies additionally functionalities such as conformal cooling channels. Aim of the present work was the design and the selective laser melting (SLM) manufacturing of an H-13 insert for extrusion dies with a conformal cooling channel. To support the design phase, numerical simulations have been carried out by including liquid nitrogen. Finally, experimental tests were successfully performed on ZM21 magnesium and AA6063 aluminium alloys confirming the efficiency of the achieved targeted cooling. INTRODUCTION The productivity of a well consolidated process such as the extrusion of aluminium profiles is strongly related the level of temperatures generated during the process itself [1]. Indeed, depending on the initial pre- heating temperatures of the billet and of the die, but especially depending on the level of deformation imposed to the forming profile, temperatures nearby the melting point of the material can be reached. An additional factor that contributes to the development of the high temperature field is the friction at the billet/tool interfaces that need to be overcome and that required a further amount of work at the press then converted into heat [1]. The detrimental consequences of these high temperatures are the decrease of the die lifetime and the many defects that could affect the outgoing profile such as hot cracks, tearings, pick-up. If the direct correlation between the extrusion speed and the generated temperature is accounted for, then it clearly emerges how the process efficiency and productivity are regulated by the thermal field. Among the available options to control the extrusion temperature [1-3], the use of liquid nitrogen for die cooling is still widely increasing its diffusion in leading extrusion companies in order to improve the aesthetical quality of the extruded profiles and to increment the production rates. The benefits can be summarized at two levels: liquid nitrogen initially flow in the die thus globally reducing the temperature then it transforms into gas phase thus protecting aluminum profiles surface from oxidation at high temperatures [4]. Claimed benefits are