Extrusion Experiments Research Articles

Numerical Simulation of Extrusion Process to Produce Complex Aluminum Profiles Using the ALE Approach

Although still having certain limitations, the numerical simulation technology has been increasingly applied to aid in optimizing the aluminum extrusion process and die design. In the present research, numerical simulations of the profiles extrusion process were performed, using the Finite Volume Method (FVM) and Finite Element Method (FEM) to make use of the individual merits of the Euler approach and Lagrange approach, respectively. The application of the simulation technology to produce large, complex profiles has, however, been quite limited. In order to solve the limited, numerical simulation of aluminum profiles with large and complicated cross-section in extrusion process was achieved using Arbitrary Lagrangian-Eulerian (ALE) approach, and non-uniform velocities at the die exit, leading to extrudate distortions, were predicted. Extrusion experiments proved that the die with the optimized design could circumvent the distortion problem. The numerical simulation technology can indeed be effectively used to reduce the number of die trials and offer the potential to realize zero die trial.

Effect of Punch Shapes on Micro Backward Extrusion of Brass

This study considered four types of punch, which were flat, conical, spherical and standardized punched, to investigate the effect of the punch shapes on the micro backward extrusion of brass. Brass (JIS C2600) materials were annealed at 500 °C, 600 °C, and 700 °C and resulted in different microstructures with grain sizes of 50 μm, 70 μm and 111 μm, respectively. The annealed brass materials were carefully machined as cylindrical billets with the same dimension of 1.1 mm in diameter and length. The billets were later used in the experiments of the micro backward extrusion to form cups with 1.1 mm diameter and 0.2 mm thickness. The experimental results show that the type of punch affecting load in an increasing order are spherical, standardized, conical and flat punches. The results also show that load increases with the punch speed, and reduces as grain size increases.

The influences of shear deformation on the evolutions of the extrusion shear for magnesium alloy

A new type of magnesium alloy extrusion-shear (short for ES) composite extrusion technology which combines the characteristics of direct extrusion and two pass equal channel extrusion has been put forward. The experiments of ES process and direct extrusion have been performed, and direct extrusion and ES dies suitable for industrial horizontal extruder have been designed and manufactured. Three-dimensional thermomechanical finite element models and conditions of the ES process and direct extrusion have been established. Extrusion forces and accumulated strains and stresses and temperatures evolution of the ES process have been obtained. The loads of the ES process increase obviously compared with those of direct extrusion. Maximum temperatures during the ES process are higher than those of direct extrusion. The computer simulation analyses of stress state for the billets reveal that part of the billet is exerted in four directions of compressive stress. The ES process could cause cumulative strains and shear stress in magnesium alloy billets than direct extrusion. Therefore, more grain refinements could be achieved. Based on the microstructure observations of center positions for the ES process and direct extrusion rods, grains have been effectively refined with extrusion temperature. It is found that there are many similarities between finite element simulation results and experimental results.

Green alternative aluminum extrusion process through process convergence

Green manufacturing is very important to reduce the environmental pollution and the material loss. Porthole extrusion is a useful process for producing a long aluminum cylinder tube. In this process, the initial billet is homogenized at a high temperature for a long time to improve the extrudability. The homogenization process is not only a high energy-consuming process but also a high pollution process. Therefore, an alternative process is needed for green manufacturing. In this study, a new porthole extrusion for green manufacturing was developed to reduce the energy consumption through the convergence of the homogenization heat treatment process and the billet pre-heating process. The flow stress of the initial billets with the conventional homogenization heat treatment process and the proposed converged process were obtained through the hot compression test. FE analysis was performed to assess the application of the proposed method. Through FE analysis the extrusion load, material flow, temperature, effective strain, and welding pressure were compared with each other. Finally the porthole extrusion experiment was carried out based on the result of FE analysis. As a result, it can be seen that the aluminum cylinder tube without defect can be produced by applying the proposed green extrusion process.

Evaluation of Paraffinic Mineral Oil as Lubricant in Cold Work Extrusion Process

In this paper, the effect of frictional constraint from the application of three different viscosity of additive free paraffinic mineral oil as lubricant were investigated by cold work forward plane strain extrusion experiments. The experiment used a cold work plane strain extrusion apparatus consist of a pair of taper die and a symmetrical workpiece (billet). The billet material was annealed pure aluminum A1100 with radius 5 mm in deformation area. The experimental result shows that the higher viscosity, will lead to lower friction effect to the deformed area, as well as product area.

Improvement of the thermal stability of branched poly(lactic acid) obtained by reactive extrusion

One-step reactive extrusion-calendering process (REX-calendering) has been used in order to obtain sheets of 1 mm from poly(lactic acid) modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time has been monitored in order to ascertain chain extender ratios and reaction time. Once all the parameters were optimized, reactive extrusion experiments have been performed. An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of PLA sheets manufactured by reactive extrusion. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak–Berggren equation f(α) = c (1 − α)nαm that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential methods and n-order reaction kinetics. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(α) = 2 (α1/2 − α), corresponding to a random scission mechanism for L = 2 (as well as other functions for L values up to 8), has been tested. Once optimized the kinetic model, the thermal degradation kinetics of sheets obtained by REX-calendering process was compared to that of conventional sheets and polymer matrix.

Estimation of friction factor at workpiece–die interface in combined forward and backward hollow extrusion of brass at micro scale

Friction at the workpiece–die interface significantly affects material flow behaviours in micro metal-forming processes. The purpose of this study was to estimate the friction factor at the workpiece–die interface in the combined forward and backward hollow extrusion of brass at micro scale. The effects of grain size and lubricating conditions on the friction were investigated. The brass (JIS C2700) tubes with 1·1 mm outer diameter and 0·5 mm inner diameter were annealed at 400, 500 and 600°C, and resulted in various microstructures with grain sizes of 20, 34 and 80 μm, respectively. The tubes were fabricated as 0·6 mm length specimens for the experiments of the hollow extrusion under dry, full and punch lubricated conditions. By comparing the ratios of the cup height to the rod length of the extruded specimens with the calibration curves established by finite element simulations, it is possible to estimate the friction factors in the processes. The results show that dry conditions lead to stronger friction effects and thus larger friction factors. The friction factor increased with grain size and stroke for all conditions. The estimated friction factors were in a range from 0·1 to 0·35.

Process Study for Forming a Precise Spline

A tubular shafts have been considered for weight reduction and high quality in the automobile industry. However, in the case of long and thin tubular shafts, it is very difficult to form an internal spline under a cold extrusion process due to folding and buckling. In this study, multi-stage forming is applied to form precise teeth shape in a long and thin tubular shaft. The effects of die diameter and thickness of the material are investigated and analyzed to determine the number of processes based on a FE simulation. Extrusion experiments have been performed to verify the results obtained in the FE simulation. It is confirmed through these tests that a long spline shaft with high dimensional accuracy and improved mechanical properties is formed.

Versatile Energetic Behavior of ZIF-8 upon High Pressure Intrusion–Extrusion of Aqueous Electrolyte Solutions

Metal–organic materials (MOFs) constitute very attractive materials for storage, separation, catalysis, and drug delivery because of their crystalline hybrid organic–inorganic structures and their large porous volume. Here, we report the energetic behavior, in term of storage/restoration of mechanical energy, of ZIF-8 upon high pressure intrusion–extrusion of aqueous KCl, LiCl, and NaCl solutions of variable concentration. Comparison with the energetic performances of the “ZIF-8–water” system is performed. Whatever the nature of the electrolyte (KCl, LiCl, NaCl), an increase of the intrusion pressures and thereby of the stored energy are observed with the increasing of salt concentration. However, the three studied systems differ, at least for the highest concentrations, by behaving as a shock-absorber for KCl and as a bumper for NaCl and LiCl. A combination of several characterization techniques used before and after intrusion–extrusion experiments, i.e., X-ray diffraction, solid state NMR, and N2 adsorp...

High Pressure Intrusion–Extrusion of LiCl Aqueous Solutions in Silicalite-1 Zeolite: Influence on Energetic Performances

The energetic performances of different “Silicalite-1–LiCl aqueous solution” systems were evaluated under high pressure. Depending on the LiCl concentration in the aqueous medium (0 M, 5 M, 10 M, 20 M), an increase of the intrusion and extrusion pressures and therefore of the stored (∼10, ∼13, ∼19, ∼31 J/g) and restored (∼10, ∼13, ∼18, ∼27 J/g) energies are observed. Thus, compared to the “Silicalite-1–water” system, the stored energy is tripled in the case of “Silicalite-1–LiCl 20 M” system. Several characterizations (XRD, TG, NMR, N2 physisorption, ICP/OES, ...) have been realized before and after intrusion–extrusion experiments in order to reveal the presence or the lack of defects and the possible presence of lithium ions in the material after such experiments. At the short-range order, solid state NMR spectroscopy get evidence of the presence of Q2 and Q3 groups revealing the breaking of some siloxane bridges after the intrusion-extrusion steps and thus the creation of hydroxyl groups set in evidence...

Experimental Research on Cracking Resistance of Alfalfa Seed

The compression properties of three varieties of alfalfa seeds, such as Medicago sativa L. cv. Gannong No.3, Medicago sativa L. Longdong and Medicago sativa L. cv. Golden Empress, are studied by extrusion experiments using SANS universal material testing machine. The results of Longdong alfalfa seed show that the fracture load has relation with shape and size of the alfalfa seeds. For both of ellipsoidal seed and arched seed, the fracture load of single seed is about 19N to 30N. The fracture load increases linearly with the thickness of plump seed with the ratio of thickness to width greater than 0.75. These inclusions for other two varieties are the same with Longdong alfalfa seed. This research could offer a technical basis of designing and developing of the alfalfa seeder and seed harvesting machine.

Numerical Simulation and Die Optimization Design of Extrusion Process for a Complex Hollow Aluminum Alloy Multi-Hole Die

The steady state extrusion process of a complex, multi-hole aluminum extrusion die was simulated using the Arbitrary Lagrangian Eulerian (ALE) algorithm. According to the numerical simulation results and the extrusion experiment, a combined method of modifying the portholes, double-step welding chamber and adjusting bearings were proposed for qualified profiles. In this study, the influence of the shape of portholes and double-step welding chamber on the material flow velocity distribution at the outlet were emphatically analysed, and some reference value for the designing and modifying of multi-hole die is existed basing on the method.

Hot Extrusion of Hollow Helical Tubes of Magnesium Alloys

This study investigates analytically and experimentally extrusion processes of magnesium alloy hollow helical tubes by a single-cylinder extrusion machine. The plastic flow pattern of the billet inside the die with a helical shape is simulated using the finite element analysis. The effects of the die bearing length, spiral angle, extrusion speed, initial temperature, and petal number on the largest extrusion loads, the filling ratios, and the product temperature distributions are discussed. Hot extrusion experiments are conducted with a set of forming parameters chosen from the analytical results, which can generate a greater filling ratio. Sound products are obtained and microstructure observations and hardness tests are also conducted at the cross-section of the product. The experimental values of extrusion loads and filling ratios are compared with the analytical values to verify the validity of the analytical model.

Performance Evaluation of Lubricant for Producing Smooth Surface Product in Cold Extrusion of Aluminum Using Tool with Micro-groove Arrays

The effects of lubricating oil on surface quality of the extruded aluminum product were investigated by carrying out a series of plane strain cold extrusion experiments. The forming dies of extrusion apparatus were assembled with a combination of the taper die and the plane plate tool with the micro-groove arrays formed on its surface. Four lubricants were tested by using the above apparatus. Then, adhesion of aluminum billet to the surface section of the plane plate tool on which the micro-groove arrays were formed, surface roughness of the billet after passing through the above section of the plane plate tool and surface conditions of the billet and tool at the die bearing section of a tool were investigated, and performance evaluation of lubricant for producing smooth surface product could be carried out successfully.

Recycling of Aluminum Chips by Hot Extrusion with Subsequent Cold Extrusion

In this paper, the direct conversion of AA6060 aluminum alloy machining chips into finished products by hot extrusion with subsequent cold extrusion is investigated. For hot extrusion, two different types of extrusion dies, a conventional flat-face die and an experimental die, are used. The experimental die combines the process of equal channel angular pressing with the process of hot extrusion in a single die, which increases the strain and pressure affecting the chips during extrusion, both critical factors for achieving sound chip bonding. Subsequently, the chip-based extrudates are machined to fabricate chip-based preforms for the cold extrusion experiments. In order to investigate different processing routes, forward rod extrusion and backward can extrusion trials were conducted. In all steps, cast material was processed similar to the chips as a reference. The results showed that the quality of the chip-based finished parts strongly depends on the bonding quality between the individual chips, determined during the hot extrusion process.

Influence of Ultrasonic Vibration on Metal Plastic Forming

Establish the ultrasonic single-point extrusion experiment platform to carry out the experiment of conventional extrusion and ultrasonic extrusion for different materials. Compared with experimental results, explore volume effect of ultrasonic vibration plastic forming and analyze the impact of different amplitude of ultrasonic resonance on material's plastic deformation volume. It can be found that ultrasonic vibration has an influence on stress-strain of material to a certain extent. Take advantage of the MSC.Marc finite element simulation software to continually modify the stress-strain curves of the material, finally the simulation result coincides with experimental conclusion. The results show that ultrasonic vibration has a significant impact on metal forming, improving the flowing property of metallic material processing, and softening materials, which further proves that ultrasonic vibration has great effects and provides the theoretical basis for it in material of plastic processing application.

Effects of Grain Size and Lubricating Conditions on Micro Forward and Backward Hollow Extrusion of Brass

Grain size and lubricating conditions influence material flow behaviours in micro metal forming processes. In this study, the brass (JIS C2700) tubes with 1.1 mm outer diameter and 0.5 mm inner diameter were treated by annealing at 400 °C, 500 °C and 600 °C to obtain various microstructures with the grain sizes of 20 μm, 34 μm and 80 μm, respectively. The treated tubes were machined and grounded to be 0.6 mm length specimens for the experiments of micro forward and backward hollow extrusion. Three lubricating conditions, which were dry, full and punch lubricated conditions, were carried out in the experiments. By comparing the upper cup height and rod length of the extruded specimens with the calibration curves established by finite element simulations, it is possible to estimate the friction factors in the processes. The results show that the dry conditions lead to stronger friction effects and thus larger friction factors. Moreover, the friction factor increased with grain size and stroke for all conditions.

Adaptation of in-line ultrasonic velocimetry to melt flow measurement in polymer extrusion

Pulsed wave velocimetry (PWV) is an ultrasonic technique for measuring velocity profiles in flowing liquids. In capillaries, PWV requires using ultrasound transducers with high center frequencies and a large bandwidth. This type of transducer is restricted to operating temperatures below 50 °C. However, in polymer extrusion, velocity profiles of flowing liquids with temperatures up to 250 °C are of interest. This contribution describes the development of a new ultrasonic measurement tool, which is fully integrated in a heated capillary die. It enables long-time measurement of the extrudate using the buffer rod technique and active cooling. The developed prototype was successfully validated in an extrusion experiment: the velocity profile of glass-fiber-filled polypropylene was measured immediately after extrusion in a capillary die.

Extrusion Process Modeling for Aqueous-Based Ceramic Pastes—Part 2: Experimental Verification

In the Part 1 paper, a constitutive law for the extrusion process of aqueous-based ceramic pastes was created. In the study described herein, a capillary rheometer was used to calibrate the viscosity of an alumina paste, and a single extruder system was used to conduct extrusion experiments to validate the constitutive model. It is shown that the extrusion response time and its change both depend on the amount of air in the extruder and the magnitude of the extrusion force. When the extrusion force is small, the rapid change of extrusion response time gives the extrusion dynamic an apparent quadratic response. When the extrusion force is large, the extrusion response time changes slowly, and is dominated by a first-order response. Air bubble release was observed in some of the experiments. A series of simulation and experimental studies were conducted to validate the predictive capabilities of the constitutive model for both steady-state and transient extrusion force behaviors. Good agreements between the simulation and experimental results were obtained. The experimental results demonstrate that the constitutive model is capable of capturing the characteristics of the highly nonlinear response at low extrusion forces and the air bubble release phenomenon. The numerical studies show that the decrease in the extrusion force during an air bubble release depends on the volume of the air bubble.

Design and experiments of extrusion die for polypropylene five-lumen micro tube

Abstracts Polymeric multi-lumen micro tube is formed by extrusion die with asymmetric flow channels. Due to the flow imbalance of polymer melts, it is difficult to design the extrusion die. In this paper, the extrusion die of a five-lumen micro tube was studied. The relationship between the structural parameters of asymmetric flow channels in right-angle extrusion die was built on the basis of flow balance of polymer melts. In the opposite direction of extrusion die channel, the lengths of the flow channels were calculated by the relationship, and the ends of the lengths were fitted. An objective function for the structural optimization of the flow channel in right-angle extrusion die was established through the fitting deviations. Then, the right-angle extrusion die for five-lumen micro tubes was designed according to the optimization results and manufactured by micro EDM machining technology. The uniform sections of extrusion products obtained by extrusion experiments with the designed and manufactured die verified the correctness of the asymmetric flow channels of extrusion die for five-lumen micro tubes. Finally, effects of extrusion process parameters on the shape accuracy of five-lumen micro tubes, evaluated by the ovality of profiles, were investigated experimentally with polypropylene as extrusion material. The optimal combination of process parameters including air injection velocity 6 ml/min, die temperature 202 °C, screw speed 16 r/min, vacuum degree of the water tank 0 and the pulling speed 10 m/min was concluded, which improved the sectional shape accuracy of the extruded micro tube by 33.6%. The ovality of outside profile, main lumen and secondary lumen in the tube section were optimized by 2.88%, 2.09% and 3.9%, respectively with the optimal combination of process parameters.