Extrusion Force Research Articles

Finite Element Analysis of Extrusion Force and Work Characteristics of ECAP

A planar finite element model is created for modeling the equal channel angular pressing (ECAP) processing of copper, by which the technological parameters can be determined for different initial parameters of the ECAP process. The structure of the model is described, as well as the extraction of the force and work data, furthermore results for the effect of the initial parameters, e.g. the friction and the frictional model on the extrusion force and work characteristics are shown.

Effects of extrusion speed and printing speed on the 3D printing stability of extruded PEEK filament

In fused deposition modeling (FDM) using polyether-ether-ketone (PEEK), the dimensions of extruded filaments are unstable and there is insufficiency dimensional agreement between the fabricated part and design model. The present study presents the effects of the extrusion speed and printing speed on the microstructure and dimensions of an extruded PEEK filament in 3D printing. The extrusion process characterization including extrusion force and extrusion resistance was measured for the understanding of the evolution of extrusion process with the increase in extrusion speed. The relationship between the extrusion speed and the diameter of the extruded filament was established by measuring the diameter of the extruded filament at different extrusion speeds in freeform extrusion. Furthermore, PEEK was stably printed in an experiment with increasing printing speed and it was revealed that the control algorithm that mathematically replaces the nozzle diameter with the diameter of the extruded filament is feasible and effective. During PEEK FDM, the melt pressure in the chamber directly affects the surface morphology and extrusion diameter of the extruded filament, and higher melt pressure is beneficial to reducing surface defects of the extruded filament. A fluctuating extrusion force is the main constraint on the stability of extrusion. The optimized control algorithm between the extrusion speed and the diameter of the extruded filament improve the stability of PEEK FDM and improves the dimensional accuracy and surface morphology of printed PEEK parts. Furthermore, this study could be applied to reveal the instability of extrusion and select a set of suitable printing parameters during FDM.

Optimal Design of the Process for Self-lubricating Spherical Plain Bearings Based on Finite Element Analysis

As a key technology for forming of self-lubricating spherical plain bearing, extrusion forming process affects general performances of self-lubricating spherical plain bearing. In order to solve the problems of insufficient force of the extruder and material accumulation of outer ring blank in the extrusion process of wide series and large bearing, a scheme of machining extrusion groove on outer ring blank is put forward, and taken numerical simulation by explicit dynamic finite element code LS-DYNA. Effective plastic plain and effective stress and bearing osculation after springback are investigated as well as applied extrusion force. The experimental results show that the bearing osculation can meet the requirement after machining extrusion groove on outer ring blank, meanwhile, a smaller extrusion force is needed in the extrusion forming process.

Experimental research of the frictional condition in the pipes extrusion process

The article demonstrated the results of an experimental study of the pipe extrusion process using the method of coordinate grids. The estimation of the influence of separate conditions of friction on the contact surfaces of the deformable material and the pressing tool on metal flow pattern. The calculation of the forming operation is made for extrusion process stages. It is shown that the deformation proceeds non-uniformly. At the same time, due to the creation of favorable conditions on the contact surfaces with the use of the lubricant, the deformable sample differs uniformly in the distribution of the coordinate grid along the wall thickness of the tube’s sample. The boundary stagnation zones are identifying. It has been demonstrated that the front portion of the sample tubes is not fully worked through the wall thickness. While, the rear section is characterized by a dense grid structure. This in combination allows us to indirectly judge the possible anisotropy of the properties along the body of extruded pipes. It is proved that the using of lubricants on the contact surface: the press needle – inner surface of the sleeve will not have a significant effect on the extrusion force, and can be used mainly to ensure the durability of the press tool and to perform the quality characteristics of the inner surface of the extruded tubes. It was concluded that, first of all, the requirements for thermo-technical properties: heat capacity and thermal conductivity, and, secondarily, frictional, must be imposed on lubricants used for coating the inner surface of the sleeve and, accordingly, providing a separation layer between the press needle and the sleeve.

Extrusion of Al-Si alloy compacts under conventional conditions and in the semi-solid state

.In this research work the results of hot extrusion process of aluminium alloy compacts conducted at the temperature of conventional hot extrusion as well as at the temperature range corresponding to the semi-solid state were presented. Initial material was prepared by uniaxial pressing of Al17Si5Fe3Cu1.1Mg0.6Zr alloy powder. The extrusion process was carried out under isothermal conditions, and the temperature stability was strictly controlled. The changes of extrusion force in relation to punch displacement were recorded during hot deformation to demonstrate the effects associated with the appearance of the liquid phase in the volume of the processed material. After extrusion the samples were cooled in water as well as at room temperature. The influence of temperature of extrusion and the resulting fraction of the liquid phase in the processed material on its microstructure and chosen mechanical properties were determined. Mechanical properties of the examined alloy after deformation were carried out by measuring the hardness and in uniaxial compression tests. Additionally, one of the compacts was remelted and cast, what made possible comparison of the microstructure and chosen properties of the obtained products. In the result of the investigations it has been proved, that extrusion in semi-sold state results in reduction of forces necessary to complete deformation process and leads to obtaining the material with good mechanical properties and fine-grained, favourable microstructure.

Simulation of the Final Stage of the Direct Extrusion Method of Large-Size Rods at Small Elongations

A simulation of the direct extrusion method of large-size rods with diameters of 188, 214, 252, 283, 326, and 560 mm made of alloy 7075; coefficients of friction of 0 and 0.5; and die cone angles of 80° and 90° from a container with a diameter of 800 mm using a 200-MN press with the help of the DEFORM-2D software package is performed. The distribution of radial velocities of metal flow on a working surface of a pressure pad depending on the contact friction, die cone angle, and elongation ratio at the main and final stages of extrusion is found. The butt-end height at the beginning instant of funnel formation is accepted equal to the distance between the pressure pad plane and input plane of extruded metal into a screw channel of flat or cone dies. The combined effect of the elongation ratio, coefficient of friction, and die cone angle on the butt-end height, extrusion force, intensities of strain rates and stresses, and temperature on the die orifice edge is investigated. Numerical experiments are performed according to the complete factorial plan 23 for variability intervals of parameters: Х1 = 3–9, Х2 = 0–0.5, Х3 = 80°–90°. Friction between the tool and the billet at the final stage of extrusion plays a negative role, noticeably decreasing the radial velocity. This leads to the earlier onset of the formation of the central funnel. Extrusion into a conical die and an increase in the elongation ratio, on the contrary, increase the radial flow velocity and provide the later onset of formation of a central funnel. The main factor that determines the butt-end height is the elongation ratio. A mathematical model is proposed to select the butt-end thickness for concrete extrusion conditions of large-dimensioned rods with small elongation ratios.

A aluminum alloy extrusion die structure on the large flat tube

The factors on premature failure of the traditional extrusion die for the big flat tube profiles were introduced. And the characteristics of the conventional structure was analyzed. Through an actual sample, a new type of hollow die structure for these profiles was presented. The composition elements of the new die structure were described. The selection of the main structural parameters was explained, and the characteristics of this new structure was described. In particular, the metal feeding way of this structure can greatly reduce the extrusion force. The new die structure has obvious advantages, which could greatly improve the die life. This is a type of die structure which is worth promoting.

SIMULATION OF FINAL DIRECT EXTRUSION STAGE FOR LARGE RODS WITH LOW EXTRUSION RATIO

The direct extrusion of large 7075 alloy bars 188, 214, 252, 283, 326, 560 mm in diameter was simulated with 0 and 0,5 friction coefficients, 80° and 90° die cone angles from the 800 mm diameter container at the 200 MN press using the DEFORM-2D software package. It provided the distribution of metal flow radial velocities on the dummy block working surface versus the contact friction value, die cone angle and extrusion ratio factor at the main and final stages of extrusion. Butt-end height at the beginning of back-end extrusion defect formation was taken equal to a distance between the dummy block plane and the plane of extruded metal feeding into flat or cone die openings. The joint effect of the extrusion ratio factor, friction coefficient and die cone angle on the butt-end height, extrusion force, deformation and stress intensity factors, and die opening edge temperature was studied. Numerical experiments were performed based on the 23 complete factorial design for the following parameter variability intervals: Х1 = 3÷9, Х2 = 0÷0,5, Х3 = 80÷90°. Friction between the tool and the blank at the final extrusion stage has a negative effect due to a noticeable radial velocity reduction. This leads to the earlier initiation of central back-end extrusion defect formation. Extrusion into the conical die and increasing the extrusion ratio factor, on the contrary, speeds up radial flow velocity and ensures that the back-end extrusion defect starts forming later. The main factor that determines butt-end height is the extrusion ratio factor. A mathematical model is proposed to select the butt-end thickness for specific conditions of extruding large bars with low extrusion ratios.

Kinematic analysis of the Ordos block and surrounding area based on GPS data: an initiative–passive vortex structure model

The counterclockwise rotation of the Ordos block has a complex geodynamic background. The fracture zone around the Ordos block also has complex stress and strain fields. We propose an initiative–passive vortex structure model (I–P model) to explain the geodynamics of the Ordos block and the surrounding fracture zone. We analyze the relative velocity of the fracture zone around the Ordos block based on the GPS velocity field and use a multiple kernel function to calculate the strain field in the study area. According to the fault distribution and tectonic activity, we divide the fracture zone around the Ordos block into seven sections and use the I–P model to analyze the relative motion state and strain variation in these sections. The results show that the north and south margins of the Ordos block exhibit sinistral strike–slip movement, primarily because the eastward movement of the Ordos block is faster than the movement of the Yanshan block and slower than that of the Southern China block. The east and west margins of the Ordos block exhibit dextral strike–slip movement, mainly due to the counterclockwise rotation of the block. The NE extrusion force from the Tibetan Plateau increases the strike–slip rate of the eastern Ordos block. The I–P model perfectly explains the change in strain around the block. It also systematically explains the regional dynamic background of the area around the Ordos block. According to the I–P model and the surface strain characteristics inside the Ordos block, we find that a tensile belt runs from the southwest to the northeast. This means that the block will probably disintegrate in the future, and the length-to-width ratio of the block will be seriously unbalanced. Therefore, the Ordos block will no longer rotate counterclockwise. The I–P model agrees with the kinetic characteristics of the present vortex structure and will provide a reference for further research on the Ordos block.

Study on Die Structure for Reducing Extrusion Force of Porthole Die

The composition of extrusion force was analyzed. The die structures to reduce the force were put forward, such as reducing mold thickness and the compression area of metal feeding, the hollow bridge number, using the inclined surface of the metal feeding and the front feeding plate, the structure of porthole that one divides into two, the larger the feeder ratio. And the methods of chamfering in inlet of the bridge and appropriate reaming of porthole are also effective. Practice shows that reducing the height of chamber and decreasing the length of bearing are also available. These structures are verified by practice and the effect is good. The aim is to provide reliable reference to colleagues.

Inline quantification of extrudability of cementitious materials for digital construction

Digital construction (DC) is a new process, and hence, no standard experimental methods for process-specific material characterization are as yet available. This article proposes a methodology for characterizing the extrudability of cement-based materials for DC, both quantitatively and inline. A 3D-printing test device was used for this purpose, which enabled the elimination of most artefacts in the characterization of materials. Unit extrusion energy UEE, defined as the energy consumed per extruded unit volume, was used as the measure of extrudability, lower UEE implying higher extrudability. The results obtained using the proposed approach were compared with results of a simple ram-extruder, slump-flow and viscometer tests. Two fine-grained concrete mixtures under investigation, one with ordinary sand and one with very fine sand, having respective yield stresses of 306.2 Pa and 642.7 Pa, were characterized. They showed a significant difference in their extrudability: the UEE needed in the case of material with finer sand was 1.62 times higher than that of the mixture with coarser sand. Interestingly, average ram extrusion force for the finer mixture was much lower than that of the coarser mix, underlining the challenges in material characterization and the need to consider the possible artefacts of various testing methods. Comparative analyses substantiated the significance of the proposed inline extrudability quantification method for DC.

Susceptibility for extrusion welding of AlMg alloys

The extrusion of hollow profiles from high strength aluminium alloys through porthole dies causes serious problem in practice. Mainly, this is due to low weldability of these alloys and high extrusion force. The present paper discusses the investigations undertaken to determine the weldability of hard AlMg alloys using the original method and device. Main advantage of the proposed method is that it allows for the reflection of real welding conditions occurring in a welding chamber of the porthole die. Weldability tests were performed for alloys: 5754 (3.5% Mg), 5083 (4.5% Mg), 5019 (5.6% Mg) and 5xxx (7.1% Mg) in a wide range of temperature, unit pressure (normal compressive stress) and duration of welding. Microstructure and strength properties of the welds were examined. Most favourable welding conditions for the tested alloys, allowing for obtaining high strength welds were defined. To validate the laboratory experiments the extrusion trials were performed in the industrial conditions, in which the round tubes from 5754 alloy were produced using the porthole dies. The tensile strength of the welds in the extruded tubes is comparable to that for the solid material. Strength of the welds as well as of the solid material strongly increases with magnesium content in the alloy.

Interrelation among the handling, mechanical, and wear properties of the newly developed flowable resin composites

ObjectivesThis study investigates the handling, mechanical, and wear properties of the newly developed flowable resin composites and elucidate the interrelations among the tested parameters. MethodsSix flowable and two conventional resin composites are used. Five measurements are performed per resin composite to obtain the average inorganic filler content. Ten specimens per material are used to obtain the flexural strength, flexural modulus, and resilience. For sliding impact wear testing, twelve specimens are prepared. Noncontact profilometer and confocal laser scanning microscopy are used to determine the maximum facet depth and volume loss. Extrusion force and thread formation are used to measure the handling properties of the flowable resin composites. Six measurements are performed per flowable resin composite. Data evaluation is performed using analysis of variance and Tukey's honestly significant difference test at an α-level of 0.05. The correlation between the tested parameters is verified using the Pearson product-moment correlation coefficient. ResultsA subset of flowable resin composites exhibits higher flexural properties and wear resistance as compared to the conventional resin composites. The handling properties of the flowable resin composites are material dependent. ConclusionWhile the resilience parameters exhibit an extremely strong and statistically significant correlation with the wear parameters, the handling properties exhibit no interrelation with the remaining parameters. SignificanceWhile the handling properties of the newly developed flowable resin composites did not correlate with the mechanical and wear properties, some new flowable resin composites have the potential for use in high-stress bearing areas, such as posterior lesions, because of the enhanced mechanical properties and wear resistance.

A Numerical Study on Co-Extrusion to Produce Coaxial Aluminum-Steel Compounds with Longitudinal Weld Seams

The use of lightweight materials is one possibility to limit the weight of vehicles and to reduce CO2 emissions. However, the mechanical properties and weight-saving potential of mono-materials are limited. Material compounds can overcome this challenge by combining the advantages of different materials in one component. Lateral angular co-extrusion (LACE) allows the production of coaxial semi-finished products consisting of aluminum and steel. In this study, a finite element model of the LACE process was built up and validated by experimental investigations. A high degree of agreement between the calculated and experimentally determined forces, temperatures, and the geometrical shape of the hybrid profiles was achieved. In order to determine suitable parameters for further extrusion experiments, the influence of different process parameters on material flow and extrusion force was investigated in a numerical parametric study. Both the temperature and extrusion ratio showed a significant influence on the occurring maximum extrusion force as well as the material flow inside the LACE tool. The maximum force of 2.5 MN of the employed extrusion press was not exceeded. An uneven material flow was observed in the welding chamber, leading to an asymmetric position of the steel rod in the aluminum matrix.

Kefiran biopolymer: Evaluation of its physicochemical and biological properties

Kefiran, an exopolysaccharide produced by lactic acid bacteria, has received a great interest due to a variety of health claims. In this study, we aim to investigate the physicochemical and biological properties of Kefiran polysaccharide extracted from Portuguese kefir grains. The kefir growth rate was about 56% (w/w) at room temperature and the kefir pH after 24 h was about 4.6. The obtained yield of Kefiran polysaccharide extracted from the kefir grains was about 4.26% (w/w). The Kefiran structural features were showed in the 1H nuclear magnetic resonance spectrum. The bands observed in the infrared spectrum confirmed that the Kefiran had a β-configuration; and the X-ray photoelectron spectroscopy analysis confirmed the structure and composition of Kefiran and revealed a C/O atomic ratio of 1.46. Moreover, Kefiran showed an average molecular weight (Mw) of 534 kDa and a number-average molecular weight (Mn) of 357 kDa. Regarding the rheological data obtained, Kefiran showed an interesting adhesive performance accompanied by a pseudoplastic behavior, and the extrusion force of Kefiran was 1 N. Furthermore, Kefiran exhibited a higher resistance to hyaluronidase degradation than hyaluronic acid. Finally, Kefiran showed a lack of cytotoxic response through its ability to support metabolic activity and proliferation of L929 cells, and had no effect on these cells’ morphology. Our research suggested that Kefiran polymer has attractive and interesting properties for a wide range of biomedical applications, such as tissue engineering and regenerative medicine.

Nozzle clogging factors during fused filament fabrication of spherical particle filled polymers

Fused filament fabrication with reinforced or filled polymers provides improved material properties compared to ordinary feedstock. A current limitation of these materials is the occurrence of nozzle clogging at higher filler contents. In this work, an experiment is designed to identify the factors causing nozzle clogging. Glass sphere-filled polycarbonate is investigated by varying nozzle and filler diameters, the resin viscosity, the filler content, and the extrusion pressure. Equations identifying nozzle clogging and intermittent clogging conditions are provided. Based on these results, a model for the clogging of sphere-filled polymers is proposed. Last, a mathematical model is derived, which approximates the printability of filled polymers without the preparation of composites. This model is based on the nozzle geometry, the filler type and content, the resin viscosity, and the printer’s maximum extrusion force.

Force changes associated with different intrusion strategies for deep-bite correction by clear aligners.

To investigate the relationships among different intrusion patterns of clear overlay aligners and the corresponding orthodontic forces and to provide guidance for clinical treatment. Five sets of removable thermoplastic-formed aligners with the same thickness, designed for different intrusion procedures (G0 aligners as a control group, with no activation; G1 aligners for intruding canines; G2 aligners for intruding incisors; G3 aligners for intruding canines and incisors with the same activations; G4 aligners for intruding canines and incisors with different activation), were manufactured, and the corresponding intrusion forces were measured with a multiaxis force/torque transducer measurement system in real time. With the same activation (0.2-mm intrusion) and rectangular attachments placed on the premolars and first molars, the canines experienced the largest intrusive force when intruded alone using G1 aligners. The canines received a larger intrusive force than incisors in G3. The incisors received similar forces in G2 and G3. First premolars endured the largest extrusive forces when all anterior teeth were intruded with G3 aligners. Extrusion forces were exerted on canines and lateral incisors when using G4 aligners. Aligners with different intrusion patterns exert different forces on incisors, canines, and premolars, and the forces were closely related to the designed activation, shape and position of the attachment and relative movement of the adjacent teeth.

Extrusion process of 316LN L-shape stainless steel and manufacture process of ITER side correction coil box

316 L N L-shape stainless steel is used in ITER Side Correction Coil (SCC) box. Finite Element Method (FEM) simulation is adopted to analyze metal flow characteristics, forecast extrusion force and ascertain extruder tonnage of 316 L N L-shape stainless steel during extrusion process. Based on simulation results, 316 L N round forged billet is used to manufacture L-shape stainless steel by extrusion process. The extrusion process includes circular furnace preheating, induction heating, glass lubrication, mould design and deformation design. 316 L N L-shape stainless steel is manufactured by Φ360 mm circular container and 60 MN horizontal extruder successfully. Mechanical properties and microstructure of 316 L N L-shape stainless steel all accord with the requirements of ITER SCC box. SCC box case is manufactured by bending, machining and welding processes. X-ray, ultrasonic testing (UT) and penetration testing (PT) are used to inspect the welding quality of SCC box case. The SCC box case passes the acceptance of ITER project expert group, this result verifies that the extrusion process and manufacture process are reasonable and feasible.

A biomechanical case study on the optimal orthodontic force on the maxillary canine tooth based on finite element analysis.

Excessive forces may cause root resorption and insufficient forces would introduce no effect in orthodontics. The objective of this study was to investigate the optimal orthodontic forces on a maxillary canine, using hydrostatic stress and logarithmic strain of the periodontal ligament (PDL) as indicators. Finite element models of a maxillary canine and surrounding tissues were developed. Distal translation/tipping forces, labial translation/tipping forces, and extrusion forces ranging from 0 to 300 g (100 g=0.98 N) were applied to the canine, as well as the force moment around the canine long axis ranging from 0 to 300 g·mm. The stress/strain of the PDL was quantified by nonlinear finite element analysis, and an absolute stress range between 0.47 kPa (capillary pressure) and 12.8 kPa (80% of human systolic blood pressure) was considered to be optimal, whereas an absolute strain exceeding 0.24% (80% of peak strain during canine maximal moving velocity) was considered optimal strain. The stress/strain distributions within the PDL were acquired for various canine movements, and the optimal orthodontic forces were calculated. As a result the optimal tipping forces (40-44 g for distal-direction and 28-32 g for labial-direction) were smaller than the translation forces (130-137 g for distal-direction and 110-124 g for labial-direction). In addition, the optimal forces for labial-direction motion (110-124 g for translation and 28-32 g for tipping) were smaller than those for distal-direction motion (130-137 g for translation and 40-44 g for tipping). Compared with previous results, the force interval was smaller than before and was therefore more conducive to the guidance of clinical treatment. The finite element analysis results provide new insights into orthodontic biomechanics and could help to optimize orthodontic treatment plans.

Hyperdilution of CaHA fillers for the improvement of age and hereditary volume deficits in East Asian patients.

With their high elasticity and viscosity, calcium hydroxylapatite (CaHA) fillers are now widely used to treat age-related or hereditary facial soft tissue volume deficits. CaHA filler volume augmentation is further enhanced by its ability to stimulate neocollagenesis and improve skin quality. However, its high viscosity and cohesivity may hinder its spread and distribution, while its injection by cannula or needle may require moderate extrusion force and lead to uneven distribution or focal accumulation in tissues. Thus, new or modified delivery techniques and tools have emerged, particularly from East Asian physicians. One such technique is hyperdilution with diluents such as lidocaine or normal saline. CaHA hyperdilution appears to be more frequently used by experienced injectors who have varying methodologies. Here, we demonstrate the precise delivery of diluted filler to treat indications related to hereditary volume deficits, volume loss, or aging in the periorbital, nasolabial and submalar regions, marionette lines, and hollowed mid-facial areas. Regardless of age or indication, dilution eases filler delivery for the injector, while using lidocaine as the diluent decreases patient discomfort and minimizes pain. Increasing injection diluent volumes reduces filler thickness (viscosity) and facilitates its even spread, encouraging skin stimulation through more direct contact with tissues and minimizing unevenness. Our results effectively demonstrate that hyperdilution is an innovative and positive evolution in CaHA filler delivery.