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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.

The aim of the present work was the assessment of the impact of deep-rolling and shotpeening performed in the underhead and in the unthreaded shank of two high strength screws (36 NiCrMo and 42 CrMoV) for fatigue life enhancement. The experimental tests consisted of six combinations, including the non-treated state. The aforementioned treatments were evaluated alone or with shot-peening performed after deep-rolling in the underhead fillet of the screws. Deep rolling was carried out at the optimal rolling force, whereas two shot diameters were considered for shotpeening (Z100 and UFS70). The results showed a beneficial impact of deep rolling on fatigue, especially for the 42 CrMoV steel. Instead, shot-peening generally leads to a worsening of the fatigue limit in relation to the induced superficial roughness.

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.