Extrusion Force Research Articles

Effects of Process Parameters on Hot Extrusion of Hollow Tube

The control of hot extrusion process is a highly complicated task due to high deformation and high billet temperature during the process. A high-quality product can be produced by controlling the process temperature. In this present study, hot extrusion process of hollow tube is modeled by finite element method. Effects of process parameters, initial billet temperature, ram displacements, reduction of area, semi-die angle, and friction coefficients are studied. Finite element results are compared with the experimental results from previous studies. The results reveal that there is a good agreement between simulations and experiments. It is determined that reduction of area and friction coefficient have strong effects on surface temperature and extrusion force. The surface temperature is increased with increasing ram displacement and decreased gradually at the exit of the die due to heat transfer with the environment. Extrusion forces are increased up to friction coefficient of 0.35 for 13 and 25% reduction of areas. However, extrusion forces are not changed significantly after 0.2 coefficient of friction for 37 and 48% reduction of areas.

Theoretical and Experimental Investigation of Hydromechanical Extrusion Process

The theoretical and experimental investigation of the process of hydromechanical extrusion (HE) of aluminum alloys Al 5056 was carried out. The aim is to determine the optimal parameters of this process. These parameters were determined to minimize the extrusion force and damage factor of a workpiece by using explicit finite elements method. The results were presented in a visual form and were shown that use of active friction forces reduces the extrusion force. Statistical processing of the experimental data gave regression equations for definition the damage factor and the value of the specific extrusion stress.

Homogenized Porcine Extracellular Matrix Derived Injectable Tissue Construct with Gold Nanoparticles for Musculoskeletal Tissue Engineering Applications

A unique porcine extracellular matrix (ECM) derived injectable tissue construct with 100 nm or 20 nm gold nanoparticles (AuNP) was developed for musculoskeletal tissue engineering applications. ECM has been shown to encourage cellularity and tissue remodeling due to its release of growth factors while AuNP have been shown to reduce reactive oxygen species (ROS) levels. Injectable tissue constructs were created by homogenizing decellularized porcine diaphragm tendon conjugated with 100 nm or 20 nm AuNP at 1x, 4x, and 8x concentrations. Extrusion force testing demonstrated that homogenized tissue constructs were injectable at an appropriate cannula size and force. L-929 murine fibroblasts were used to measure cell viability, cell proliferation, intracellular ROS levels, and cell migration in response to constructs. Enhanced cell viability and proliferation are observed on 1 × 20 nm AuNP constructs. ROS assays demonstrate reduced cellular ROS concentrations from all 20 nm AuNP constructs and from 8 × 100 nm AuNP constructs compared with constructs without nanoparticles. Cellular migration is higher towards 4 × 20 nm AuNP constructs compared with constructs without nanoparticles. Results support the potential use of a porcine ECM derived injectable tissue construct with AuNP as an injectable tissue construct to reduce inflammation and to promote tissue remodeling in musculoskeletal tissue engineering applications.

Investigation of Clad Wire Production by Conclad Extrusion with Twin Wheels

Abstract Conform continuous extrusion is a unique extrusion process in which the extrusion force originates in the frictional force between the feedstock and wheel. When this extrusion process is applied to conclad extrusions, however, the metal flow is highly complex and hitherto undetermined. In this study, a model experiment and numerical model were developed, to elucidate the material flow. Previous studies have shown that, in conform devices consisting of one wheel with twin grooves, dead metal in the chamber is incorporated into the product and the joining pressure is not strong. To address these problems, a novel experimental device, consisting of twin wheels, was designed, which succeeded in preventing the incorporation of dead metal into the product; however, numerous relevant characteristics and problems have not yet been elucidated. The present study investigated the effect of differing tool geometries in such a device. Based on experimental results using modeling material, it is clear that the feedstock diameter should be determined with consideration of the joining pressure and product yield ratio. Further, scrapers influence the metal flow in front of the abutment, and are clearly important for ensuring smooth metal flow along the path. Finally, based on the numerical simulation results, it is clear that the gap between the wheel groove and abutment is important for preventing the oxide surface of the feedstock from being incorporated into the product; however, as the gap increases, the joining pressure decreases.

Numerical study and genetic algorithm optimization of hot extrusion process to produce rectangular waveguides

Rectangular waveguide is one of the earliest types of transmission lines. Rectangular waveguide can be produced by hot extrusion process. In this paper, the hot extrusion process of CuZn5 rectangular waveguide was investigated by Finite Element Method (FEM). In addition, Genetic Algorithm (GA) was used to optimize the die geometry and process conditions to achieve the lowest magnitude of extrusion force. Die geometry was introduced in terms of die length and billet hole diameter under various frictional conditions. It was found that die length and billet hole diameter had contradictory effects on the extrusion force. The experimental study was also carried out to verify the accuracy of estimated results.

Slit-Robo Repulsive Signaling Extrudes Tumorigenic Cells from Epithelia

Cells dynamically interact throughout animal development to coordinate growth and deter disease. For example, cell-cell competition weeds out aberrant cells to enforce homeostasis. In Drosophila, tumorigenic cells mutant for the cell polarity gene scribble (scrib) are actively eliminated from epithelia when surrounded by wild-type cells. While scrib cell elimination depends critically on JNK signaling, JNK-dependent cell death cannot sufficiently explain scrib cell extirpation. Thus, how JNK executed cell elimination remained elusive. Here, we show that repulsive Slit-Robo2-Ena signaling exerts an extrusive force downstream of JNK to eliminate scrib cells from epithelia by disrupting E-cadherin. While loss of Slit-Robo2-Ena in scrib cells potentiates scrib tumor formation within the epithelium, Robo2-Ena hyperactivation surprisingly triggers luminal scrib tumor growth following excess extrusion. This extrusive signaling is amplified by a positive feedback loop between Slit-Robo2-Ena and JNK. Our observations provide a potential causal mechanism for Slit-Robo dysregulation in numerous human cancers.

Effect of Temperature and Strain Rate on the Mechanical Properties of 99.5 Aluminium Rods Extruded by KOBO

In this study, aluminium rods were cold extruded in a direct process by KOBO method in two variants: variant I with varying (decreasing) frequency of die oscillations necessary to maintain a constant extrusion force, and variant II with constant frequency of die oscillations, leading to a decrease in the extrusion force. The tensile test of rods was carried out in a temperature range of 20 - 200°C and at a strain rate from 8xE10-5 to 8xE10-1 s-1. Significant differences in the elongation of the tested rods were observed. It was found that rods extruded at variable die oscillations and stretched at room temperature had similar elongation, independent of the strain rate. With the increase of temperature, the elongation of samples stretched at a low speed was growing from a value of about 8% at room temperature up to 40% at 200°C. At high strain rates, despite the increasing temperature, the elongation remained at the same level, i.e. 5-6%. In rods extruded at constant die oscillations, the elongation at a low strain rate was growing with the temperature from 10% at room temperature up to 29% at 200°C. At high strain rates, the elongation decreased from 28% at room temperature to 11% at 200°C. The results were interrelated with examinations of the structure of rods and fractures of tensile specimens. In the material extruded by KOBO method with constant die oscillations, the beginnings of the recrystallization process were observed, absent in the material extruded at variable die oscillations.

Initial forces experienced by the anterior and posterior teeth during dental-anchored or skeletal-anchored en masse retraction in vitro.

To investigate initial forces acting on teeth around the arch during en masse retraction using an in vitro Orthodontic SIMulator (OSIM). The OSIM was used to represent the full maxillary arch in a case wherein both first premolars had been extracted. Dental and skeletal anchorage to a posted archwire and skeletal anchorage to a 10-mm power arm were all simulated. A 0.019 × 0.025-inch stainless steel archwire was used in all cases, and 15-mm light nickel-titanium springs were activated to approximately 150 g on both sides of the arch. A sample size of n = 40 springs were tested for each of the three groups. Multivariate analysis of variance (α = 0.05) was used to determine differences between treatment groups. In the anterior segment, it was found that skeletal anchorage with power arms generated the largest retraction force (P < .001). The largest vertical forces on the unit were generated using skeletal anchorage, followed by skeletal anchorage with power arms, and finally dental anchorage. Power arms were found to generate larger intrusive forces on the lateral incisors and extrusive forces on the canines than on other groups. For the posterior anchorage unit, dental anchorage generated the largest protraction and palatal forces. Negligible forces were measured for both skeletal anchorage groups. Vertical forces on the posterior unit were minimal in all cases (<0.1 N). All retraction methods produced sufficient forces to retract the anterior teeth during en masse retraction. Skeletal anchorage reduced forces on the posterior teeth but introduced greater vertical forces on the anterior teeth.

Modeling and optimization of cold extrusion process by using response surface methodology and metaheuristic approaches

Obtaining the optimal extrusion process parameters by integration of optimization techniques was crucial and continuous engineering task in which it attempted to minimize the tool load. The tool load should be minimized as higher extrusion forces required greater capacity and energy. It may lead to increase the chance of part defects, die wear and die breakage. Besides, optimization may help to save the time and cost of producing the final product, in addition to produce better formability of work material and better quality of the finishing product. In this regard, this study aimed to determine the optimal extrusion process parameters. The minimization of punch load was the main concern, in such a way that the structurally sound product at minimum load can be achieved. Minimization of punch load during the extrusion process was first formulated as a nonlinear programming model using response surface methodology in this study. The established extrusion force model was then taken as the fitness function. Subsequently, the analytical approach and metaheuristic algorithms, specifically the particle swarm optimization, cuckoo search algorithm (CSA) and flower pollination algorithm, were applied to optimize the extrusion process parameters. Performance assessment demonstrated the promising results of all presented techniques in minimizing the tool loading. The CSA, however, gave more persistent optimization results, which was validated through statistical analysis.

Late Cenozoic stress state distributions at the intersection of the Hellenic and Cyprus Arcs, SW Turkey

The history of the Late Cenozoic stress regime was determined for an area between the gulfs of Fethiye and Antalya. Fault kinematic analysis and inversion of focal mechanisms of shallow earthquakes reveal significant evolution of the regional stress regime in SW Anatolia, i.e., the area of interaction between the Hellenic and Cyprus arcs, from the Mio-Pliocene to the present time. Fault kinematic analysis yields two different normal faulting stress regimes along the southwestern part of Fethiye-Burdur Fault zone, e.g., in and around Çameli Basin (Zone A1) and two different strike-slip to normal faulting stress regimes characterized by a roughly orthogonal set of extensional axes between Fethiye and Demre (Zone B) with an older NW–SE σ3 axis for Mio-Pliocene and a younger NE–SW σ3 axis for Plio-Quaternary time. Inversion of focal mechanisms of the earthquakes occurring in Zone A1 provides an extensional stress state with approximately N-S σ3 axis. Inversion of those occurring in Zone B, south of Zone A1, yields a dominantly strike-slip stress state with a NE-SW σ3 axis and a NW-SE σ1 axis respectively. The inversion slip vectors from fault planes yield a consistent normal faulting stress regime in Burdur Basin and its surroundings (i.e., along the northeastern part of Fethiye-Burdur Fault Zone, (Zone A2)) during Plio-Quaternary, continuing into recent time as indicated by earthquake focal mechanism inversions. Both states have a consistent NW–SE σ3 axis. Fault kinematic analysis indicates NW-SE extension acting in Zone C (subarea between Demre and Antalya), south of Zone A2, during Mio-Pliocene time. The inversion of focal mechanisms yields normal faulting also characterized by a consistent NW-SE σ3 axis. The nearly orthogonal extensional stress regimes (NW-SE and NE-SW) obtained by inversion of both measured and seismic faults seem to have been acting contemporaneously with each other at different intensities from the Mio-Pliocene onwards in SW Turkey. This may be attributed to the geodynamic effects related to the subduction of the African plate beneath Anatolia diffusing along the Hellenic and Cyprus arcs and in the west-southwestward extrusion of Anatolia. The cause of the early NW–SE extension is the slab-pull force due to the subduction process along the Cyprus arc, considered to be dominant until the Plio-Quaternary in the western part of the study area in zones A1 and B. The dominant status of the Cyprus arc continues today in the eastern part of study area in zones A2 and C. The later NE–SW to present day approximately N–S extension, dominant since the Plio-Quaternary, is related to the combined forces of the Anatolian extrusion and the subduction process along the Hellenic arc.

Effects of raw material particle size on the briquetting process of rice straw

Biomass feedstocks need to be milled or chopped into particles before briquetting, and the particle size has great effects on the energy consumption and product quality. In this study, the effects of the particle size on the rice straw briquetting process were investigated. The raw materials were milled or chopped into four different sized test materials. Experiments were carried out with an electronic universal testing machine and a self-designed single pellet unit on the basis of a simplex-centroid design. Several parameters, including briquetting time, energy consumption, maximum extrusion force, product compressive strength, and product density, were tested and recorded. The experimental data were processed by the methods of regression analysis and variance analysis. Finally, effects of raw material particle size on the briquetting process, energy consumption, maximum extrusion force, product compressive strength, and product density were obtained. Results showed that, compared with simple sized materials, mixed materials achieved lower energy consumption, higher product compressive strength, and higher product density.

Rheological and thermogelling properties of commercials chitosan/β-glycerophosphate: Retention of hydrogel in water, milk and UF-milk

This study shows that how commercial chitosans owing three different molecular weights and high degree of acetylation can be neutralized closed to physiological pH using β-glycerophosphate to produce liquid solution at room temperature and formation of hydrogel upon subsequence heating up to the biological temperature (37 °C). The addition of β-glycerophosphate provided the precise buffering, controlled hydrophobic interaction and hydrogen bonding in order to retain chitosan in solution at 22 °C and neutral pH, and allowed gel formation upon heating up to 37 °C. Examination of flow and dynamic rheological properties, extrusion force and energy, heat induced gelation and gel stability of selected chitosan evidenced the flow performance and frequency dependent of elastic and viscous modules, extrusion ability, establishment of sol/gel diagram and retention of gel in three food mediums including water, pasteurized milk and ultrafiltered milk. It appeared that strength of gel network is governed by molecular weight and the higher molecular weight provided the superior gel strength. The study on retention of selected hydrogel in different mediums revealed that water has the most affinity to maintain the gel network.

Sensitivity analysis on ram speed of a direct extrusion process model using a porthole die through CEL method

In this paper, a tube extrusion process by finite element was analyzed, using coupled Eulerian-Lagrangian method (CEL) due to the severe deformation that material presents and thereby avoids distortion of the mesh and adaptive meshing used in Lagrangian models, in order to obtain stress distribution, strains, extrusion force, and flow material behavior. Four isothermal models were performed by modifying the sensitivity of ram speed using discrete rigid tools with general contact option to simulate the interaction between them; 7005 aluminum was considered as the material to be extruded. In order to reduce high computational time application, speed was increased to observe its influence on the results, in other words the variations between the models. As a consequence of this analysis, it was found that while the kinetic energy does not exceed 5 to 10 % of whole internal energy, material flow behavior and stress level are not affected.

Semi-Theoretical Analyses on Mechanical Performance of Flexible-Belt Shearing Extrusion Walnut Shell Crushing

<abstract> <b><i><ext-link ext-link-type=uri xlink:href=http://dict.youdao.com/w/abstract/>Abstract</ext-link></i></b> To complement the process of breaking walnut shells with mechanical approaches, a walnut shell-kernel separation device was designed. Stiffness at different positions of the walnut shell was analyzed by the theory of elastic mechanics, which contributed the critical force of instability of different positions. The internal force and deformation of the walnut shell upon extrusion were analyzed by the theory of thin shells. The results showed that the position at which the forces are concentrated is the point of fracture. The critical force of cracking and breakage at different positions of the walnut shell were reported. Based on the flexible-belt shearing extrusion breakage system, conditions for the walnut entering the extrusion space as well as the squeezing-in angle (?₀) and the extrusion angle (?) of the walnut during breakage were assessed theoretically and empirically. Results show that when 0°<?₀?44°, the walnut can enter the extrusion space. When the upper working belt (i.e., the squeezing roller) is 23 mm away from the lower working belt, walnut shells crack when ? is 20° and break when ? is 15°. A mathematical model of extrusion force and shear force on walnut shells by upper and lower working belts was built theoretically. Conditions for crack extension after walnut shell breakage were analyzed and calculated by the fracture mechanics theory. The results demonstrated when the mean crack length is 20 mm, the critical external force for crack extension is 19.1 N.

Forward extrusion of bulk wood containing polymethylmethacrylate: Effect of polymer content and die angle on the flow characteristics

In this study, the forward extrusion of non-pulverized bulk wood containing polymethylmethacrylate (PMMA) was investigated to obtain new fundamental insights regarding the plastic forming of bulk wood. In particular, we studied the effect of the polymer content and die angle (20°–120°) on the extrusion forces and flow of various types of bulk wood during extrusion. Plastic-impregnated wood (composite) specimens with high (49%) and low (27%) polymer content were obtained by impregnating wood with solutions containing different concentrations of methyl methacrylate (MMA). Before the impregnation, the wood was hydrophobized by acetylation to allow the MMA to penetrate into the cell walls. The load during extrusion for the 49% composite was lower than that for the 27% composite at all die angles. For both composites, the extrusion force increased with decreasing die angle for small die angles (20°–40°) because of the increase in friction force at the die wall surface. For the 27% composite, the extrusion force increased with increasing die angle beyond 40° due to the formation of dead zones and shear zones in the wood. Therefore, the optimal die angle that minimized the extrusion force was near 40°. In contrast, the extrusion force for the 49% composite exhibited no significant difference for die angles larger than 40° in spite of the formation of dead zones and shear zones. Chevron cracking appeared in the 49% composites, whereas no cracks and voids were formed in the 27% composites.

Extrusion limit diagram of IN 690 super-alloy tube based on hot processing map

Extrusion limit diagram can be used to locate available deformation conditions for materials. The developed extrusion limit diagram of IN 690 (Inconel 690) tube was constructed through a new method by integrating analytic method, FE simulation and hot processing map. Extrusion force limit curve determined by the maximum extrusion pressure of the extruder, and temperature limit curve defined by the melting temperature of the material, which are two conventional curves for extrusion limit diagram, were obtained through FE simulations. Based on the hot processing map, high power dissipation efficiency limit curve calculated through analytical equations was firstly employed to construct the developed extrusion limit diagram. The overlap of reasonable regions bounded by these curves not only ensures smooth extrusion process, but also guarantees qualified products. Given that some special conditions were verified through FE simulations and one condition was validated through the on-site testing, the optimum region on the extrusion limit diagram is thus authentic and practical for the extrusion process of the IN 690 tube.

A new porous block sonotrode for ultrasonic assisted micro plastic forming

The micro plastic forming process (MPFP) was a developing method widely used for the fabrication of miniature metallic parts. A hybrid MPFP assisted by ultrasonic vibration could be helpful to reducing forming load and improve product quality. In the ultrasonic assisted MPFP, the ultrasonic vibration was usually superimposed on the forming punch but seldom on the workpiece although the ultrasonic vibration of the workpiece could improve the micro-formability of material more effectively. This phenomenon was partly due to the weight and random shape of the workpiece. To realize the ultrasonic vibration of the workpiece in MPFP, a new type of porous block sonotrode was developed in this study. The sonotrode could convert the ultrasonic vibration from longitudinal direction to normal direction and get uniform amplitude on the central square radiant surface. It could also excite the micro workpiece or mold with resonant vibration along the normal direction and was insensitive to the fluctuation of structure and weight of micro workpiece. The simulated analysis and experiment results show that the porous block sonotrode can excite micro workpiece with ultrasonic resonant vibration, reduce the average extrusion force over 15 % and increase the extrusion height over 85 %.

Determination of processing power and optimum billet radius of modified backward extrusion by upper bound approach

A recently developed backward extrusion method entitled “modified backward extrusion” was presented using an upper bound analysis. For this purpose deformation area was divided into four distinct zones and a kinematically admissible velocity field for each of them was suggested. Total dissipated power was calculated for the deformation zones and the extrusion power was computed. The correlations of important geometrical parameters with extrusion force and dissipated powers were shown. Finding the initial billet size, a challenging area in the modified backward extrusion method, was discussed and the optimum billet radius was obtained, considering the minimum relative extrusion pressure. Finite element analyses were conducted and the results were compared with the upper bound analysis. Finally, experiments were executed on commercially pure aluminium and a good agreement between upper bound and finite element analyses with experimental values was observed.

Investigation on the effect of titanium (Ti) addition to the Mg- AZ31 alloy in the as cast and after extrusion conditions on its metallurgical and mechanical characteristics

Magnesium-aluminum alloys are versatile materials which are used in manufacturing a number of engineering and industrial parts in the automobile and aircraft industries due to their strength - to -weight -ratios. Against these preferable characteristics, magnesium is difficult to deform at room temperature; therefore it is alloyed with other elements mainly aluminum and zinc to add some required properties particularly to achieve high strength -to- weight ratio. Grain refinement is an important technology to improve the mechanical propertiesand the microstructure uniformity of the alloys. Most of the published work on grain refinement was directed toward grain refining aluminum and zinc alloys; however, the effect of the addition of rare earth material on the grain size or the mechanical behavior of Mg alloys is rare. In this paper the effect of Ti addition on the grain size, mechanical behavior, ductility, extrusion force and energy, of Mg-AZ31 alloy both in the as cast condition and after direct extrusion is investigated.

The water holding ability of powder masses: Characterization and influence on the preparation of pellets via extrusion/spheronization

The water holding ability of powder masses greatly influences their extrusion/spheronization performance during pellets preparation. To quantify this ability and explore its influence on pellets preparation, two characterized parameters were proposed. One was the maximum water content that could be retained by the mass (WHAmax), the other was the remaining water content in the mass subjected to certain extrusion force (WHAextrusion). The methods to determine WHA were established by centrifugation. MCC, κ-carrageenan, mannitol were employed to investigate the relationship between WHA and their extrusion/spheronization performance. The results showed that the WHAmax and WHAextrusion of MCC were 1.0g/g and 0.85g/g, which were less than that of κ-carrageenan (WHAmax>6.0g/g, WHAextrusion=3.0g/g), accordingly. Since mannitol had the lowest parameter values (WHAmax=0.3g/g, WHAextrusion=0.25g/g), it was hard to be extruded. Therefore, κ-carrageenan (≥10%) or mannitol (≥30%) were added to prepare satisfactory pellets by increasing the WHA values (≥0.53g/g) of the mixed masses. In addition, the WHA of mixed masses could be predicted based on WHA of each mass. To obtain enough extrudates and non-agglomerated pellets, the water content added in the mass should be equal with WHAmax. In conclusion, the established two parameters were useful to predict the extrusion/spheronization performance of masses, therefore, selecting the potential pelletization aids and determining the optimal water content.