Search results for "Extrusion"
showing 10 items of 142 documents
EBSD, XRD and SRS characterization of a casting Al-7wt%Si alloy processed by equal channel angular extrusion: Dislocation density evaluation
2019
Abstract Aluminum‑silicon (Al Si) alloys of high silicon contents are composite materials; they are used whenever high casting properties are required. They are slightly ductile below 8wt%Si. An increase in ductility can be obtained by refining Si-crystals in elaboration or by a further hot working. In the present work, an Al-7wt%Si alloy was processed by Equal Channel Angular Extrusion (ECAE) at temperatures 20 °C and 160 °C up to three passes. The die was formed by two cylindrical channels with characteristic angles Φ = 110° and Ψ = 0. EBSD, X ray diffraction (XRD) and Strain Rate Sensitivity (SRS) were used to characterize the microstructure and the mechanical properties. High levels of …
Magma extrusion during the Ubinas 2013-2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring
2015
International audience; After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013–2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intr…
Thermoplastic starch and green tea blends with LLDPE films for active packaging of meat and oil-based products
2019
International audience; Thermoplastic starch (TPS) is an alternative biomaterial that can be used to produce bioplastics to replace petroleum-based food packaging. Active films were developed from acetylated cassava TPS and green tea using the blown extrusion process. Green tea (GT) and TPS from native starch (NS) and acetylated starch (AS) with different degrees of substitution (DS) were extruded with linear low-density polyethylene (LLDPE) at LLDPE/TPS-GT ratios of 70/30 and 60/40 prior to blown-film extrusion. Results indicated that a higher DS of AS enhanced melt flow index which altered processability and subsequently impacted film microstructures and physical and barrier properties. N…
Energy demand reduction of aluminum alloys recycling through friction stir extrusion processes implementation
2019
Abstract Aluminum alloys are characterized by high-energy demands for primary production. Recycling is a well-documented strategy to lower the environmental impact of light alloys production. Despite that, conventional recycling processes are still energy-intensive with a low energy efficiency. Also, permanent material losses occur during remelting because of oxidation. Recently, several solid-state recycling approaches have been analyzed; in fact, by avoiding the remelting step both energy and material can be saved and, therefore, the embodied energy of secondary production can be substantially reduced. In this paper, the solid-state approach Friction Stir Extrusion (FSE) is analyzed for a…
Mechatronic Design for an Extrusion-Based Additive Manufacturing Machine
2017
3D printers, especially in the implementation of innovative extrusion processes which do not have a long history of development, are often built by adapting mechanical designs, drives and controls previously developed for generic machine tools. This is done through a process of choice and integration which is based principally on empirical criteria and taking into account separately the different aspects and parameters. Hereafter, we present an integrated mechatronic approach which has been adopted to design from the scratch a machine to implement the innovative metal injection moulding (MIM) technology. Its extrusion rate involves the adaptation of the generated trajectories and consequent…
On the Heuristic Procedure to Determine Processing Parameters in Additive Manufacturing Based on Materials Extrusion
2020
We present a heuristic procedure for determining key processing parameters (PPs) in materials-extrusion-based additive manufacturing processes. The concept relies on a design-of-experiment approach and consists of eleven &ldquo
Process mechanics in Friction Stir Extrusion of magnesium alloys chips through experiments and numerical simulation
2017
Abstract Friction Stir Extrusion (FSE) is a novel process designed to directly recycle machining chips. An experimental campaign was carried out on AZ31 milling chips using variations in extrusion ratio, force and tool rotation rate. The process mechanics were studied and correlated to the material flow, which was elucidated through use of a copper marker. A 3D, Lagrangian, thermo-mechanically coupled dedicated numerical model was set up and validated through temperature measurements. The combination of experimental and numerical results permitted to reconstruct the complex 3D material flow induced by tool rotation and plunge into the extrusion billet chamber.
An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components
2021
In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit fo…
A numerical model for Wire integrity prediction in Friction Stir Extrusion of magnesium alloys
2017
Abstract A numerical model for the prediction of the wire quality produced by the novel direct machining chip recycling technique known as Friction Stir Extrusion (FSE) is presented. Wire microstructure and wire integrity have been predicted by embedding in the code the equations enabling the calculation of the Zener-Hollomon parameter as well as the W parameter of the Pivnik-Plata solid bonding criterion. The proposed model, developed for the AZ31 magnesium alloy using the commercial simulation package DEFORM, is 3D Lagrangian, thermo-mechanically coupled with visco-plastic material behavior. The model was first validated against experimental temperature measurements and then used to predi…
Influence of processing parameters and initial temper on Friction Stir Extrusion of 2050 aluminum alloy
2017
Abstract Friction Stir Extrusion is an innovative production technology that enables direct wire production via consolidation and extrusion of metal chips or solid billets. During the process, a rotating die is plunged into a cylindrical chamber containing the material to be extruded. The stirring action of the tool produces plastic flow in the extrusion chamber, densifying and heating the charge so that finally, fully dense rods are extruded. Experiments have been carried out in order to investigate the influence of process parameters and initial temper of the base material on the process variables and on the extrudates’ mechanical properties.