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Magnesium is classified as lightweight material and as biomaterial because of its low density and good biocompatibility and biodegradability in the human body. It is therefore expected to be applied as microforming technical components and medical engineering products. Because of its close-packed hexagonal lattice structure, Magnesium and typical magnesium alloys such as AZ31 are known to have low ductility and poor formability in cold forming processes.

A strategy to adjust the product geometry autonomously through an online control of the manufacturing process in incremental sheet forming with active medium is presented. An axial force sensor and a laser distance sensor are integrated into the process setup to measure the forming force and the product height, respectively. Experiments are conducted to estimate the bulging behavior for different pre-determined tool paths. An artificial neural network is consequently trained based on the experimental data to continuously predict the pressure levels required to control the final product height. The predicted pressure is part of a closed-loop control to improve the geometrical accuracy of formed parts. Finally, experiments were conducted to verify the results, where truncated cones with different dimensions were formed with and without the closed-loop control. The results indicate that this strategy enhances the geometrical accuracy of the parts and can potentially be expanded to be implemented for different types of material and geometries. A strategy to adjust the product geometry autonomously through an online control of the manufacturing process in incremental sheet forming with active medium is presented. An axial force sensor and a laser distance sensor are integrated into the process setup to measure the forming force and the product height, respectively. Experiments are conducted to estimate the bulging behavior for different pre-determined tool paths. An artificial neural network is consequently trained based on the experimental data to continuously predict the pressure levels required to control the final product height. The predicted pressure is part of a closed-loop control to improve the geometrical accuracy of formed parts. Finally, experiments were conducted to verify the results, where truncated cones with different dimensions were formed with and without the closed-loop control. The results indicate that this strategy enhances the geometrical accuracy of the parts and can potentially be expanded to be implemented for different types of material and geometries.

Press hardening process can benefit the formability of 22MnB5 in high temperature and high strength as a final product. It is widely used for weight reduction of car body without sacrifice of its crashworthiness. Nevertheless, not only strength but also stiffness is important for some vehicle components. Press hardening of tube using granular media is the possible technology to realize the press hardening process for tubular components, which have much higher stiffness as compared to sheet metal parts. To choose appropriate granular media, instrumented die compaction test and high pressure direct shear test were established to characterize the material property of granular material. A hot tensile test was used to determine the formability of 22MnB5 tube material. Interaction between granular media and tube material including friction coefficient and heat transfer coefficient was measured by shear test and heat transfer test. Based on these works, a thermal–mechanical coupled finite element model was used to analyses the process. In validation experiment, a T-shape specimen was formed and quenched. Process parameters such as loading force, interfacial friction, and tube geometry were also investigated via numerical and experimental research for a better understanding of the process. The interfacial friction between granular media and tube showed significant effects to the forming result. These effects were represented by process parameters such as friction coefficient, tube length, types of granular media. A multi-type granular media brought out higher pressure transfer effect and also reduced interfacial friction force, which showed better formability.

The purpose of this paper is twofold: first, it aims to characterize plastic flow and ductile fracture in sheet-bulk indentation and, second, it proposes a closed-form analytical framework that can be easily applied to estimate the through-thickness pressure and force that needs to be applied by a flat compression punch as a function of the geometry, the mechanical properties of the blanks and the friction along the blank–tool interfaces. The methodology combines experiments with properly designed tool systems, which facilitate or constrain material to flow sideways (in the direction of the length), and analytical developments build upon the upper bound method for upsetting, transition to die filling and die filling of sheet-bulk compression by a flat punch. Experimental work with aluminium EN AW-1050A shows that depending on the geometry of the punch, the physics of sheet-bulk indentation may exclusively involve plastic flow or may result from a combination of plastic flow and fracture to detach surfaces from the neighbouring regions of the blank through controlled crack propagation. Results also show that the mechanics of sheet-bulk indentation can be easily and effectively analyzed by means of sheet-bulk compression under plane strain conditions.

Composite profiles composed of aluminum base material and steel reinforcing elements manufactured by bar extrusion exhibit residual stresses. These stresses occur due to the different thermal shrinkage of the materials during cooling of the profile. In this paper, the residual stresses are investigated by means of analytical and numerical analyses. The influence of the reinforcing volume and the material behavior, i.e. the plastification of the base material, is discussed. Furthermore, the residual stresses in symmetric profile cross sections with multiple reinforcings are examined and compared to the stresses in a simple composite rod with a centric reinforcing.

Solid state recycling of aluminum chips by hot extrusion is a novel processing technique, which utilizes remarkably lower energies compared to conventional recycling by remelting. The mechanical properties of the extruded profiles can be improved by optimizing the effect of extrusion die design on the welding quality of machining chips. The chips were extruded through two dies of different design to produce solid rectangular profiles. One of the dies was a flat-face die, which represents a conventional extrusion die design for production of solid aluminum profiles. The second die was a porthole die typically used for complex hollow and semi hollow aluminum profiles. AA6060 chips were compacted at room temperature into billets and hot-extruded at approximately 500 °C to aluminum profiles. The microstructure and the mechanical properties of the profiles extruded through the flat-face and porthole dies were compared. The extrusion through the porthole die resulted in a much better welding of the chips and revealed more than 80% higher ductility compared to the profiles extruded through a flat-face die. The welding quality of the chips was studied using a two-step analytical approach: a criterion for the breaking of the oxide layers and an index for the welding quality. These analytical approaches were implemented with the help of subroutines in the FEM code, in which the results of the simulations were compared and confirmed by the experimental results.

The benchmark is aimed at exploiting FEM codes capabilities and users' knowledge in the simulation of an industrial extrusion process which as it was realized and monitored by the conference organizers. The comparison of the "blind" simulations by the participants with the experimental results should allow users to check if their settings are generally adequate to the problem and software house to verify the sensitivity of their solving methods. The paper describes the settings to properly run the problem simulations and summarize the main outputs.

In order to improve the mechanical properties of profiles extruded from aluminum chips, a four turn equal channel angular pressing tool was integrated into an extrusion die (iECAP die). AA6060 aluminum alloy turning chips were cold pre-compacted to chip-based billets and hot extruded through the iECAP die on a conventional forward extrusion press. Mechanical properties and microstructure of the chip-based billets extruded through the iECAP die were investigated and compared to those extruded through a conventional flat-face die and a porthole die. To evaluate the performance of the iECAP processed chip-based profiles, conventional cast billets were extruded through the flat-face die as a reference material. To investigate the influence of temperature on mechanical properties and microstructure of chip-based profiles, the extrusion was performed at 450 °C and 550 °C. Tensile tests revealed superior mechanical properties of the chip-based billets extruded through the iECAP die in comparison to chip-based billets extruded through the flat-face and the porthole die as well as to cast billets extruded through the flat-face die.

Background: The two major isoforms of the human amyloid precursor protein (APP) are APP695 and APP751. They differ by the insertion of a Kunitz-type protease inhibitor (KPI) sequence in the extracellular domain of APP751. APP-KPI isoforms are increased in Alzheimer’s disease brains, and they could be associated with disease progression. Recent studies have shown that APP processing to Aβ is regulated by homodimerization, which involves both extracellular and juxtamembrane/transmembrane (JM/TM) regions. Objective: Our aim is to understand the mechanisms controlling APP dimerization and the contribution of the ectodomain and JM/TM regions to this process. Methods: We used bimolecular fluorescence complementation approaches coupled to fluorescence-activated cell sorting analysis to measure the dimerization level of different APP isoforms and APP C-terminal fragments (C99) mutated in their JM/TM region. Results: APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain of APP or C99 did not significantly affect fluorescence complementation. Conclusion: These findings indicate that the KPI domain plays a major role in APP dimerization. They set the basis for further investigation of the relation between dimerization, metabolism and function of APP.

This paper focuses on new extrusion processes for the improvement of product quality, the reduction of process chains and the saving of our available resources. The presented and discussed technologies cover the extrusion of reinforced profiles, curved profiles and twisted profiles. Besides, the process principles and advantages, several results from numerical and experimental investigations are given in order to show the motivation for fundamental and application oriented research in the field of extrusion technology.

The present paper investigates the grain size evolution in aluminium alloys AA 6082 and AA 7020 during hot forward extrusion process. The aim of the present work is the definition and implementation of a predictive algorithm that is able to compute the evolution of the grain shape during the process within the finite element method code Deform. Extrusion experiments were performed at two levels: at reduced scale for investigating and identifying the predictive equations and at industrial scale for validating the developed algorithm. At small scale extrusion, a complete factorial plan was performed for two alloys at three different temperatures, three extrusion ratios and two ram speeds: the discards and extrudates from the experiments were quenched immediately in order to avoid any potential recrystallisation, hence allowing measurements of transitional processing steps. At the industrial scale, instead, the 7020 alloy was extruded with two different die designs, thus producing a 20 mm diameter round bar under different extrusion ratios and strain paths. Finite element simulations were initially validated over visioplastic investigations in order to establish an accurate computation of the material flow, then experimental and numerical results were coupled, thus allowing the definition of the grain evolution model that was successfully integrated and validated on industrial scale trials.

This paper presents an overview of the two previous editions of the benchmark conferences (2009 and 2011) with a focus on experimental trials results and on the comparison of the accuracy of the different FEM codes in predicting critical process outputs. Indeed benchmark experiments are designed with the aim to focus the attention on a particular phenomenon and to check the ability of FEM codes of predicting it. Profile lengths, process load, die deflections, die, and profile temperatures which were accurately recorded during the extrusion strokes were used as benchmarking parameters for FEM comparison. Moreover, computational times, simulation set-up times, as well as information on the required hardware were compared for the proposed cases study. A detailed discussion for all output parameters is described in order to illustrate the evolution of the potentiality and limits of each code used in the last three years.

Extrusion applications require a strict control of the mechanical proprieties of the extrudates, in particular when undergoing severe loading conditions like in the transportation sector. Profile mechanical properties directly depend on its microstructure and texture, which are the result of multiple mechanisms based on precipitation mechanism or on grain shape evolution (grain refinement, recrystallizations, recovery and grain growth). In this direction, predicting the final profile microstructure under specific process parameters in the die design stage is of great relevance. The present study involved experimental activity on grain size measurements of profile and butt during interrupted direct extrusion of an AA6082 round profile. The grain size measurements were coupled with simulation results in order to regress analytical models based on effective strain, strain rate and temperature. Finally, the developed model was implemented in the numerical code by means of a subroutine that can be used as microstructure prediction tool.

Microstructure of aluminum is of high importance for product mechanical properties. During extrusion the material undergoes a wide range of different strain, strain rates and temperature gradients, how many works reported (1). Final microstructure and texture is the result of the effects of multiple mechanisms as grain shape change, recrystallization, recovery, and grain growth. To get optimized profiles a well-direct adjustment of the microstructure through process parameter is a typical and critical aim. Therefore the correlation between extrusion process parameters and the change of texture and grain size needs to be investigated (2). The present paper reports a study on grain evolution during the first stages of material response to deformation in direct extrusion process. The investigation was carried out by means of a circular profile extrusion of AA6082 alloy with the aim of evaluate dependency of texture change over process parameters such as temperatures, velocity and extrusion ratio. Sequentially experimental measurements on grain size have been coupled with strain evaluation of finite element model in order to define an evolution model, always taking into account existing evolution theories and laws.

Visioplastic analyses with the rod technique were performed in the extrusion of AA6060 alloy at different processing conditions in order to measure the friction effect at the billet-container interface. During the trials an accurate monitoring of the relevant process variables such as punch force and temperatures was performed in order to validate FEM simulations. Different FE codes were used to carry out the simulations: Deform, HyperXtrude, and Superform. A particular attention was given on evaluating the several coefficients of the available friction models by comparing the FEM results with experimental results.

Contributing to lightweight design in the field of metal forming, four different strategies are introduced – the material, component, functional, and conditional lightweight strategy. Their main objective is the reduction of a component's weight and the saving of our available resources. Regarding each approach, innovative forming technologies are presented and their contribution to lightweight success is depicted. On the one hand, this article covers conventional processes like e.g. extrusion, which are used for processing hybrid lightweight materials. On the other hand, new forming technologies are introduced to serve lightweight requirements like e.g. load adaption. Finally, the importance of numerical damage modeling regarding lightweight design is shown.

In modern lightweight concepts, for example in automotive engineering, structures are increasingly composed of several dissimilar materials. Due to the different material properties of the joining partners, conventional and widely used joining techniques often reach their technological limits when applied in the manufacturing of such multi-material structures. This leads to an increasing demand for appropriate joining technologies, like joining by die-less hydroforming (DHF) for connecting tubular workpieces. The present work introduces an analytical model to determine the achievable joint strength of this connection type. This approach, taking into account the material parameters as well as the groove and tube geometry, is based on a membrane analysis with constant wall thickness. Additionally, bending stresses and friction are considered locally. Besides a fundamental understanding of the load transfer mechanism, this analytic approach allows a reliable joining zone design. To validate the model, experimental investigations using aluminum specimens were performed.Copyright © 2014 by ASME

The objective of the study is to investigate the effect of vitamin C and E supplementation on rabbit sperm motility. Forty INAT breed bucks aged 8.5 mo were divided into 2 groups: control group (C) and treated group (T) receiving vitamins C (1 g/L) and E (1 g/L) incorporated in the drinking water. Semen was collected using an artificial vagina over 6 wk (C, total ejaculates=81; T, total ejaculates=76). The massal motility (MM) was evaluated in the fresh and raw semen. Then, the individual motility at 0 (IM0), 2 (IM2) and 4 h (IM4) after semen collection was determined in diluted semen and conserved at +4°C for the 2 groups. MM was higher in T than in C group (P=0.0012). However, the individual motilities IM0, IM2 and IM4 did not vary between the 2 groups. In conclusion, the supplementation of vitamins C and E in the drinking water for rabbit influenced only the MM in both fresh and raw semen.

Springback is considered as one of the major problems in sheet metal forming. It leads to assembly defects and cause a huge amount of cost for tool modifications. In this work a tool for incremental analysis of springback analysis has been presented. Development of springback with punch travel has been analyzed for the simple U draw-bend geometry, tunnel geometry with open base and modified tunnel geometry with closed base and variable flange height. The effect of tension variation in the sheet with punch travel has been considered as the steering parameter for the springback and various profiles of varying tension are studied, which would generate different tensile forces in sheet. It is found that the tension in the part in the last quarter of punch travel has a profound effect on the springback reduction as compared to the traditionally applied constant BHF. Two selected kinematic hardening models, namely Yoshida-Uemori(YU) model and Armstrong-Frederick(AF) model are used to study the coupled effects of tension and material hardening.

This paper presents the effect of the extrusion ratio (ER) on the mechanical properties of aluminum profiles solid state recycled from 6060 aluminum chips by hot extrusion. The chips were extruded through three different dies. The tensile test results and microstructures were discussed in comparison with the conventional profiles extruded with the same dies under the same extrusion conditions. The conventional profiles extruded with these three different ERs revealed almost the same mechanical properties. The profiles extruded from chips with an ER of 68:1 showed an approx. 20% higher strength and ductility compared to the profiles of an ER of 34:1, while the exerted pressure was not sufficient for welding the chips in case of an ER of 10:1. It was also shown that, by adjusting the material flow through the die, it was possible to recycle aluminum chips even at ERs as low as 10:1.

The process of manufacturing discontinuously non-centric steel reinforced aluminum by means of co-extrusion has been examined. By this process semi-finished reinforced profiles can be fabricated for further treatment through forging techniques. Therefore, steel reinforcement elements consisting of E295GC were inserted into conventional aluminum billets and co-extruded into two different solid profiles; a rectangle one by an extrusion ratio of 10.1:1 and a round one by 4.8:1. The used aluminum alloy is EN AW-6060. The billet temperature as well as the ram speed were varied to investigate their influence on the position of the reinforcement elements inside the strand. The measurement was done by a video measurement system, called Optomess A250, after milling off the strand. The distances between the elements in longitudinal direction were nearly constant, apart from the rear part of the strand. The same was observed for the distance of the steel elements to the profile edge. This due to the inhomogeneous material flow in the transverse weld, related to the billet-to-billet extrusion. The rotation of the reinforcement elements occurs because the elements flow nearby the shear zone. Further, micrographs were made to investigate the embedding situation and the grain size distribution. The embedding of the reinforcement elements were good in the solid round profile, but in the rectangle profile were found some kind of air pocket. The grain size of the aluminum alloy close to the steel elements is much smaller than in the other parts of the solid round profile.

In this paper, a method for the direct recycling of aluminum scrap by hot extrusion is investigated. 1050 aluminum alloy material in the form of pins remained as scrap after a lateral extrusion process and was mixed with 6060 aluminum alloy chips resulting from a turning operation. Contrary to the conventional method of re-melting aluminum scrap to produce secondary aluminum, this aluminum scrap+chip mixture was cold compacted into billets and hot extruded at 500°C to full rectangular profiles. The extruded profiles were examined by tensile tests and microstructural investigations and compared to the conventionally extruded profiles from as-cast material. It was shown that not only the aluminum chips but also the aluminum scrap material can be recycled directly by hot extrusion, which requires only ~10% of the energy required for recycling by re-melting. Also, the profiles extruded from billets containing 1050 aluminum alloy scrap with and without cooling lubricant were compared and a deteriorating effect was determined.

The paper deals with two new process variants invented by the authors. Both use the principle of stress superposition to reach an additional plastification of the material for a controlled influencing of the forming zone. By the superposition of an additional load on a forming process it is possible to compensate the springback effect e.g. of bending angles or bending radii to extend the forming limits of the material and to reduce the forming forces. The first process is the new process of incremental tube forming. This process is based on the combination of a spinning process with the free forming of tubular semi-finished products. This process is suitable to bend tubes two- and three-dimensionally to an arbitrary contour and to manufacture tailored tubes. The process is useful to bend tubes without a die with full springback compensation. The second process is an advanced sheet metal air bending process using a roll which is pushed against the bending part after the loading operation and before unloading. This results in an incremental superposition of stresses along the bent part leading to a springback reduction and improvement of the crash properties. The paper shows the principles of both procedures and presents the results of the experimental investigations.

This paper focuses on new forming techniques for the improvement of product quality, the reduction of process chains and the saving of our available resources. The presented and discussed technologies cover extrusion of reinforced profiles, bending of profiles, single point incremental forming of polymers, and tool systems made of polymers coated by hard metal as well as re-manufacturing strategies. Beside the process principles and advantages several results from numerical and experimental investigations will be given in order to show the motivation for fundamental and application oriented research in the field of forming technology.

In forming technology, the principle of stress superposition is well known for a controlled influencing of the forming zone. The aim of stress superposition is to reach an additional plastification of the material, which can be used to compensate the springback effect, e.g. of bending angles or bending radii, to extend the forming limits of the material and to reduce the forming forces. The paper deals with two new forming process variants invented by the authors, which are based on the principle of stress superposition. The first is an air bending process using an additional roll for the incremental superposition of compressive stresses along the tensile zone of a bent sheet metal. The second is the new process of incremental tube forming, which is suitable for bending tubes two- and three-dimensionally to arbitrary contours. It is based on the combination of a spinning process with the free forming of tubes.

The paper describes new developments in extrusion processes for the reduction of process chains and the improvement of the flexibility of the extrusion process itself. Hereby, the presented and discussed technology is the extrusion of profile with variable cross-sections. Besides the process principle and advantages, several results of exper mental investigations are given in order to show the motivation for fundamental and application-oriented research in the field of extrusion technology. First results on the extrusion of profiles with variable cross-section are shown in this paper. Here, the focus was placed on the development of dies for the extrusion of open and hollow profiles with variable wall thickness.

In this paper experimental investigations aimed at measuring the die deformations during aluminum extrusion process is presented and discussed. A two-holes die generating two U-shape profiles with different supporting legs was produced and tested under strictly monitored conditions. The influence of die deformation on the speed, temperature distribution and distortion of the two profiles is reported and analyzed. AA6082 alloy was used as deforming material while H-13 hot-work tool steel was selected as die material. The experiments were repeated at least three times in the same conditions in order to achieve a statistical distribution of the acquired data: such data are then used as a reference for the 2009 edition of the extrusion benchmark.

Aim of the work is to investigate different strategies in balancing material flow during direct extrusion through porthole dies. Two AA6082 hollow profiles were simultaneously extruded by a single die with different portholes extrusion ratio, dissimilar welding chambers and different bearing lengths. A strict process control was realized by measuring thermal conditions in the die by means of 6 thermocouples and on the profiles by a self calibrating pyrometer for aluminum alloy applications. Several billets were extruded at different ram speeds (2 to 7 mm/sec) and the effect of die design on surface quality, profile lengths and thermal field was recorded. The profiles were then sectioned and the position of the seam welds in the profiles identified and compared also with the profiles tip.

The 4th International Conference on Extrusion and Benchmark (ICEB 2011) will be held in Bologna, Italy from October 3-5, 2011. A large number of extruders, die makers, software houses, and researchers will gather at the event to discuss the core technology of light metal extrusion. More than 50 abstracts have been accepted on light alloy extrusion processing and the first day will be dedicated to these sessions. Papers will be also presented on ultra light alloys and new applications for extruded profiles. Process optimization and solutions to extrusion related issues will be analyzed thoroughly by several contributors. The second day of the event will be mainly dedicated to the benchmark experiment and participant results where the results of two monitored experiments will be discussed. The Scientific Benchmark will focus on the different strategies for balancing the material flow in porthole dies and its die design will deal with issues of hollow profile production, such as seam welding mechanism and material flow. The 4th International Conference on Extrusion and Benchmark (ICEB 2011) will be held in Bologna, Italy from October 3-5, 2011. A large number of extruders, die makers, software houses, and researchers will gather at the event to discuss the core technology of light metal extrusion. More than 50 abstracts have been accepted on light alloy extrusion processing and the first day will be dedicated to these sessions. Papers will be also presented on ultra light alloys and new applications for extruded profiles. Process optimization and solutions to extrusion related issues will be analyzed thoroughly by several contributors. The second day of the event will be mainly dedicated to the benchmark experiment and participant results where the results of two monitored experiments will be discussed. The Scientific Benchmark will focus on the different strategies for balancing the material flow in porthole dies and its die design will deal with issues of hollow profile production, such as seam welding mechanism and material flow.

The demand for specific properties and excellent quality of extruded aluminum profiles stretches to the limit the abilities of extruders and die makers: ever more complex sections, hard alloys, emerging technologies, and microstructure control are only some of the manufacturers’ everyday concerns. Key factors for innovation as well as competitiveness are a skilled engineering analysis and reliable software; however, no reference community exists for the extrusion analyst and a common basis for evaluating commercial codes capabilities is missing. The extrusion benchmark is a conference on the borderline of technology during which researchers, industries, and software suppliers from all over the world will show their competence in predicting the results of a real extrusion activity whose outcome is unknown and participants will get in touch with the major international experts on their use and development. In this paper, the experimental trials for evaluating codes’ capabilities in terms of analyzing real industrial problems are fully described and analyzed. The provided inputs for running the simulations are initially presented: die design, material flow stress, friction conditions, and heat exchanges are suggested to participants with insufficient experience in extrusion simulations. A brief discussion on the die design is reported in order to explain the aim of the organizers in performing testing conditions which emphasize process-related issues. A multi-hole die with four L-shaped orifices was produced with 4 different pocket shapes thus providing valuable information on material flow inside the die at different process conditions. The results of trial tests performed at the University of Dortmund are completely reported and discussed on the basis of profile length, exiting temperature and press load. Finally, a brief discussion on codes’ performance is presented and discussed so as to provide to the audience the state of the art of FEM capabilities applied to the study of the extrusion process.

The increasing demand for reliable simulation of the extrusion process has led to the organization of a biannual international conference, referred as "Extrusion Benchmark", specifically related to the optimization of FEM codes for extrusion analysis. In particular, the Extrusion Benchmark is a conference where the several commercial codes capabilities are analyzed in deep by the comparison with an extrusion experiment. The 2009 edition will be held on 16-17 September 2009 at Technische Universitat Dortmund, Germany, under the chair of Prof. A.E. Tekkaya, more info available at conference website (www.iul.eu/extrusion09). In this preliminary organization phase, more than 60 abstracts have been submitted from all around the world, the 4 biggest software houses have already confirmed their participation and 6 big aluminum extrusion market players have decided to support the conference.

Visioplasticity represent a powerful technique for Investigating material flow during bulk metal forming processing and particularly In extrusion where complex metal flows occur. In particular, gridded billets or rod Insertion techniques are used for characterize metal flow In direct and Indirect hot aluminium extrusion. In the paper reduced scale experiments were innovatively proposed in order to analyze the process tribology by means of visioplasticity of coated tools (TIN layer by means of Physical Vapor Deposition (PVD) Technique, TiC-TiN-AI2O3 layer through Chemical Vapor Deposition (CVD) Technique) comparing the results to classical uncoated tools. Reduced scale experiments provides friction conditions comparable to real scale extrusion as revealed by the comparison with a real scale extrusion of a round profile. The deformed grids were measured In order to estimate the friction effect throughout the billet length In coated and uncoated tools conditions. Numerical investigations for the qualitative and quantitative determination of friction models were carried out by means of the Deform code with different friction formulations and coefficients. It was found that uncoated tools realize a fully sticking behaviour, while die coatings allowed reducing process friction; CVD coating better fits extrusion requirements because PVD coating lost its effect after a limited number of billets.

The simulation of the extrusion process by means of FE codes has been applied in a great number of papers available in literature but its application in everyday production was limited due to several factors like computational times, user's skills as well as prediction accuracy. Indeed, the inner complexity of the process, characterized by extremely high deformations, strain rates and heat exchange phenomena, has lead only in the last few year commercial FE codes to gain sufficient accurate solving capabilities. In the paper, five FEM codes based on different approaches were applied in the simulation of the same experiment: the results were compared in term of set-up times, computational time as well as process prediction accuracy. Process load, profile speeds, die and profile temperatures were accurately monitored during the experiment in order to realize an effective comparison of the different FEM codes approaches.