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In aluminum extrusion, one of the main limit is the developed temperature field that limits the maximum achievable production rate. Liquid nitrogen cooled dies are frequently today used in industry but they remove heat far away from the bearings, where the most critical conditions are reached. The novel concept involves the use of the additive manufacturing technology (SLM) to grant a full cooling channel design freedom, including the possibility to be located nearby the bearings. The insert is fit in a steel-housing die conventionally manufactured in order to limit final die costs. A comprehensive numerical analysis has been performed with the aim to investigate the insert thermo-mechanical performances, including the nitrogen cooling effect. The achieved numerical results encouraged the experimental manufacturing and testing of the insert. Specifically, eight inserts have been produced by SLM technology and the optimal one was successfully tested in the extrusion of an aluminum alloy.

Temperature control during aluminium extrusion is a mandatory activity in order to produce defect-free profiles and to optimize process productivity. During the extrusion process, the profile exit temperature increases due to amount of work spent to overcome friction and to plastically deform the workpiece that is converted to heat. In addition, if the ram speed or the extrusion ratio increase, the temperature further raises leading to detrimental surface defects such as hot cracks. The main advantages of dissipate the excessive generated heat in the die and at the end of the forming zone are related to the possibility of increasing only slightly the extrusion force and to reduce the conduction path from the forming zone to the cooling source. In addition, it is possible to cool critical die areas directly by sizing and positioning cooling channels or cooling nozzles adequately to prevent hot cracking. However, the manufacturing of conformal cooling channels close to the main forming zone by means of conventional machining is a difficult task for profiles and dies with highly complex geometries. Thus, the use of additive manufacturing technologies is a promising approach to allow a conformal cooling. The major advantage of additive manufacturing processes against conventional subtractive methods is the geometrical freedom of the produced components and the manufacturing of conformal cooling channels. The chromium hot-work tool steels are the most widely selected materials for forging, die-casting and extrusion dies applications because of their high thermo-mechanical strength, fatigue strength, toughness and relative low cost. Nowadays, thanks to the selective laser melting (SLM) technology, it is possible to produce structures with 99% density, since the material is completely melted and later solidified without forming spherical voids [4]. Since, to date, the additive manufacturing processes are often accompanied with higher manufacturing time and costs than conventional subtractive methods, a new concept for a hybrid extrusion die is presented. In the present work, a multi-die is proposed in which the expensive AM part, the insert with conformal cooling channels, is integrated into a conventional machined steel housing. A profile produced with a short die lifetime and critical issues on thermal field has been identified and selected consisting in a round bar of 10mm diameter made by AA6060.

In the present research an innovative testing method, specifially developed to characterize the tool steels under creep-fatigue conditions, was carried out an a TQ1 (X36CrMoV5-2) hot-work tool steel in cooperation with Constellium R&D center. The experimental campaign consisted of different testing conditions and most of the specimens were nitrided to account for the specific surface state of the tools. Tests were performed on a 100kN MTS fatigue machine equipped with a heating furnace. A creep-fatigue loading type was applied to the specimens, i.e. a cyclic load with a dwell-time, in order to properly reproduce the conditions acting on extrusion tools and dies. Under a constant temperature of 520°C, the effects of four different load levels and 2 different values of dwell-times were evaluated. In addition, selected test conditions were replicated with specimens not nitrided with the aim to evalute and quantify the influence of the superficial treatment. Final results were presented in terms of fatigue curves of the TQ1 steel and compared to the performances of the H11 tool steel tested in a previous research by the same authors.

Degreasing products actually on the market to be used prior to anodizing or painting generally contain borate. Borate must be limited in the waste water leaving the plants since in EU they are not permitted anymore to be dispersed in the environment. The paper analyzes four new borate-free agents (cleaners), able to remove ink, markers, grease or solid soils adsorbed or chemically bonded to the surface of the parts. Different borate-free formulations ( 2 proposed by Italtecno MG19 NB2 and MG19 NB3and two available on the market) were tested and investigated evaluating the cleaning efficiency compared to formulation actually in use in aeronautics containing borates. The agents were also evaluated in term of corrosion or damage of these new formulations on the aluminium alloy used in the tests. The aluminum alloy under testing was 2024 unclad and with a cladding layer typically used in aeronautical applications. The paper summarize the main findings of the project BFCleaner (EU call SP1‐JTI‐CLEAN SKY‐2011‐01) funded by the European Comminuity within the Joint Tecnology Initiative “Clean sky”.

In the design of complex extrusion dies, a number of different and potentially conflicting goals are involved in the process optimization such as profile tolerances, mechanical properties, aesthetic surfaces, and die life. The aim of the present work was to carry out a multi-objective virtual optimization of industrial porthole dies for the maximization of profile quality (seam welds strength), of the production rate (flow balance and ram speed), and of die strength. Two industrial profiles were investigated, a thick round tube and a more complex industrial case of a hollow rectangular profile. In the first case, the gain achieved by the optimal design was compared with the experimental evidence of an already optimized configuration, showing an additional increase in terms of welding strength and flow balance. For the rectangular profile, the most significant improvements were attained not only for the seam weld quality, but also for the die strength, if compared to the performances of a starting configuration.

The aim of the present work is to develop a model within Qform, a Lagrangian FE Code environment to predict the grain evolution of 6XXX aluminum alloys during deformation and subsequent static recrystallization. Experimental data were obtained from backward extrusion campaigns (AA6060-O and AA6082-O) that were performed at different conditions of temperature and strain rate. All the specimens were subjected to microstructural analysis in terms of grain size: before extrusion (initial grain size), immediately quenched after extrusion (evaluation of dynamic recrystallization) and after a full annealing heat treatment (evaluation of a fully static recrystallization). The regression between experimental data and FEM computation allowed to validate a theoretical model for the grain size and shape evolution during dynamic recrystallization of 6060 and 6082 alloys previously developed on a different experimental campaign and to implement and evaluate a static recrystallization model proposed in literature (by considering 100% of recrystallization only) on AA6060 alloy.

Hot forming processes (extrusion, die ca sting and forging) allow the production of a wide variety of products, both in terms of worked material and achievable shapes. However, critical working conditions are involved for the tools subjected to severe thermo- mechanical loads, thus requiring an accurate design. Among the different classifications proposed in literature for hot forming die failures, one focus on separating manufacturing and in service failures. The latter category is additionally split, as proposed by the authors, in static failure, damage and deformation/deflec tion failures. Static failure appears after e reduced number of extruded billets as a consequence of an overload or of a poor initial die design. Damage and deflection failures are ind eed induced by the synergic detrimental action of creep and fatigue phenomenon. In disc riminating the relative dominant role of creep and fatigue in leading to the final die discard, the level of temperature and of the applied load as well as of the dwell-time are d ecisive. In extrusion, the latter is the time in which a constant load acts on the die and represents the time required to extruded each single billet function of both ram speed and billet length. Fatigue and creep can be seen as limit cases with zero and infinite dwell-time. A novel model is proposed for the prediction of the deformation undergone by hot forming t ools in the creep-fatigue regime after multiple cycles. The model is presented as applied to extrusion dies and is based on a modified version of a simple creep law already implemented in all the FE codes. The model is validated against small scale dies used in physical experiments and then against industrial extrusion dies.

none 3 no In the design of complex extrusion dies, a number of different and potentially conflicting goals are involved in the process optimization such as profile tolerances, mechanical properties, aesthetical surfaces, and die life. Thus, a robust and comprehensive approach to investigate the problem is required that must be also compatible with the industrial timing. In this context, the aim of the present work was to perform a multi-objective optimization of industrial porthole dies for the maximization of the profile quality, expressed in terms of seam weld strength, of the production rate, that means balanced exit flow and maximized velocity, and of the die strength by means of meta-models. Two aluminum profiles were investigated. First, a thick round tube manufactured by means of a porthole die with three legs was selected as a starting case to define, fix, and validate the procedure. The gain achieved by the optimal design was compared with the experimental evidences of an already optimized configuration showing an additional increase in terms of welding strength and flow balance. In the second step of the work, the virtual optimization performed by means of meta-models was applied to solve a more complex industrial case of a hollow rectangular profile with four eyelets. For this, most significant improvements were attained not only for the seam weld quality but also for the die strength if compared to the performances of a starting configuration. Barbara, Reggiani; Lorenzo, Donati; Luca, Tomesani Barbara, Reggiani; Lorenzo, Donati; Luca, Tomesani

In light alloy extrusion process, different and conflicting objectives need to be achieved during die design stage in order to obtain an efficient and robust process. Among these, the production of extruded profiles within the required tolerances is of primary importance. A secondary aim, in case of profiles used for structural applications, is to guarantee adequate mechanical characteristics. In addition, the die has to resist without yielding under the selected process conditions. All these requirements are borne by the proper setting of process parameters and by die design. An extensive number of works are reported in literature for process and die design optimization. However, all these publications show the impact of a limited number of input parameters on a specific output that optimize the profile quality or, alternatively, the die life. Just one publication reports the multi-objective optimization of an extrusion process but the methodology is not clearly reported. Aim of this work is to extend this contribution to account for several input and output variables. To this aim, COMSOL Multiphyisics ® has been integrated with modeFRONTIER and the optimized solutions extracted from the Pareto frontier.

The use and adoption of magne sium extruded profiles in structural application is limited because magnesium extrusion technology is at its first. Once extruded hollow sections will be available at a reasonable cost, a tremendous in crease of market demand is going to be expected due to the lowest weight of the magnesium alloys in comparison with aluminum based ones. The press productivity re present a key factor in this scope and the die, due to the strong incidence of strain and temperature in the extrudability, will play a basic role to achieve the required stem speed. This paper present a new approach for designing extrusion dies specifically for magnesium alloy ZM21 by means of FEM simulation. The goodness of the new design has been validated extruding an hollow profile using an industrial press with data logging.

The paper reports information in term of simulation settings and output results related to the Industrial benchmark 2015 : extrusion benchmark is an event where participants from software houses, industries and academia are re quested to simulate an extrusion process case which main experimental data are initially unknown and disclosed only after the submission of simulati on results.

Aim of t he benchmark is to examine FEM codes capabilities and users’ knowledge in the simulation of extrusion trials which were carried out and monitored by conference organizers. The comparison of the “blind” simulations by the participants with the experimental results allow s users to check if their simulation settings are generally adequate to replicate the problem and soft ware house to verify the sensitivity of their solving methods. It is very important for us to remind that, due to the complexity of this matter, it would be useless to consider the benchmark as a contest: it is, instead, an opportuni ty to fix some points a bout the e veryday simulation practice, each participant wi th his own particular interest . I n this direction no winner will be awarded at the end of the conference because a clear comparison of code’s capabilities will visibly emerge.

Extrusion of aluminum alloys, although generally considered a well established technology, is still today a manufacturing process where most of the and error approach” and where numerical techniques have only recently gained a real interest by companies. The reasons for the delay in application of numerical techniques in extrusion compared to other metal forming processes (like sheet forming, rolling, or forging) are properly and accurately analyze and predict the process In order to overcome such limitations and to provide the extrusion industry a place to discuss progress in extrusion technology with a special focus on numeri- - 1 conference series was begun in 2007.The aim of the conference is to merge the typical conference format (presentation of papers from academia and industry) with a benchmark session, where participants are asked to analyze a spe- edition, organizers decided to provide participants a wider opportunity by merging the 8th with the 9th edition of the Aluminium Two Thousand The combined congress created an attractive and unique opportunity for aluminum and light alloy researchers, technicians, technology suppliers, industry and discussing the latest research and the trends for the future. The outcome of this joined edition was beyond any expectation, with 430 participants from 50 countries (more than the sum of the two single events) and 130 technical papers. All the big global players of the aluminum market attended the conference, together with extruders and aluminum producers, small- and mediumsized die makers, and software developers.