Extrusion Tool Research Articles

Multiphysics modeling and simulation of monolayer flow and die swelling in industrial tube extrusion process

AbstractIn a regular extrusion process for thermoplastic specimen, the material behavior in dies and its rheological properties have a major influence on the mechanical properties and the quality of the extruded product. This study outlines the multiphysical model, which has been adapted to address the specific issues associated with polyamide 12 polymer extrusion. A series of numerical simulations, based on the modeling of material behavior, have been conducted using the computational code Comsol Multiphysics®. These simulations have been applied to the study of polymer melt flows through an industrial extrusion die. The objective of this study is to analyze the influence of the imposed extrusion parameters on the physical field distribution and the material displacement within the die. The die swell at the exit of the extrusion die has been investigated as a function of the imposed pressure. The progression of the polymer flow front inside the extrusion tool and the swelling rates have been analyzed. In particular, the phenomenon of delayed swelling at high pressure has been highlighted at high pressure.Highlights Polymer swelling at industrial extrusion die exit is investigated. Polymer melt extrusion within industrial extrusion tool is numerically simulated. Flow front progression and extrudate swell are analyzed. Effect of extrusion pressure on instabilities and die swell is highlighted.

Reinforcement of thin hot-stamped components by fiber reinforced plastic structures with optimized fatigue strength properties

Multi-material structures in the automotive industry hold great potential for lightweight design, body construction, and functionalization due to their favorable mechanical properties and reduced structural weight. The combination of metal and plastic, in particular, is commonly used to enhance the overall properties of the end product when compared to single-material structures.This paper describes a process development with a hot-stamping and an extrusion tool. By means of this tool, a thermally assisted extrusion process can be used to join GMT (Glass Mat reinforced Thermoplastics) and 22MnB5 steel in a single process step. Through adhesion, the GMT adheres to the rough surface of the AlSi(aluminum-silicon)-coated 22MnB5. Test components were manufactured and through static tests the influence of process parameters was evaluated. Assuming that the parameters determined for the reference component are already sufficient for a design in the vehicle, the reduction of the steel thickness of the structure from 1.5 mm to 1.2 mm can be recommended on the basis of the results obtained. This is accompanied by a reduction in the mass of the test structure used while maintaining or improving its dynamic and static properties. Further weight savings appear possible through further component and process optimization.

Connection strength analysis and prediction of external swaging based on tube deformation measurement

Fittings have extensive use in the aerospace, automotive, and other industries as they serve as sealing and connecting components for tube systems. External Swaging (ES) forming creates a permanent joint through plastic deformation of the metal. This technique is not dependent on the tube's wall thickness and offers benefits such as high-pressure resistance and effective sealing. Using the forming process of a 10 mm Ti-3Al-2.5 V tube with an adapted 21-6-9 fitting as an illustration, a three-dimensional finite element model for the entire assembly was developed. The model consists of the tube, fitting, elastic clamp, and crimping tool. The formation mechanism and joint strength of external swaging are analyzed by numerical simulation and experimental testing. The results show that during the extrusion process, the tangential contact between the extrusion tool and the elastic clamps converts external radial loads into circumferential loads, resulting in circumferential strains in the tube. Circumferential strain creates an arched sealing area between the tube and fitting contact surfaces, providing sealing and joint strength. The joint strength of 10.60 kN was determined through finite element simulation. The load required for forming is determined by analysis to be 80.13 kN. and the relationship between squeeze load, crimp volume and joint strength is clarified. The study revealed that the height of the arch area aligns with the connection strength's change rule concerning extrusion load, fitting the two found that when the external extrusion load changes, the two are linear rule of changing. Based on this, a method is suggested for forecasting the strength of a joint by measuring the height of the arch in the tube after forming.

Extrusion-based additive manufacturing of aluminium-filled ethylene vinyl acetate for electrically conductive 3D part printing

Addition of carbon-based fillers to enhance electrical conductivity is quite popular but addition of metal fillers is still a challenge due to oxidation and unavailability of metal nano-powders. In this paper, fabrication of flexible electrically conductive parts is proposed using aluminium metal powder as filler material. Aluminium metal powder is mixed with ethylene vinyl acetate (EVA) by chemical mixing process. Cyclohexane is used as a mixing medium in which EVA is dissolved and aluminium powder is added by weight. An in-house developed material extrusion tool mounted on CNC milling machine is used for printing of flexible electrically conductive samples. Pellet-based extrusion process is used for printing flexible parts as conventional filament-based 3D is not suitable due to buckling. Composite with filler loading in 5%, 10%, 20% and 30% were made and samples were printed. Investigations were made on printability of composite and its electrical conductivity. The aluminium fillers presence and dispersion in polymer were ensured. The samples were printed in temperature range of 130–140 °C through 0.4 mm diameter nozzle. It was found that the resistivity drops by around 60% on varying the filler concentration from 20% to 30%; 81.6 kΩ is the lowest resistance observed with 30% filler concentration. A simulation study on thermal behaviour of material extrusion tool has been done and is validated practically. The application of flexible electrically conductive parts lies in fabrication of various electronic devices like antenna, display boards, solar panels, and wearable health monitoring devices.

Investigation on using graphite filler for 3D printing of flexible electrically conductive polymer by extrusion‐based additive manufacturing

AbstractThe rapid use of additive manufacturing (AM) in electronic industry identifies the need of flexible electrically conductive materials suitable for 3D printing. Challenges like buckling of flexible filament and complexity in addition of conductive fillers makes pellet‐based extrusion the most suitable alternative for part printing. In the present work, graphite powder is combined with ethylene vinyl acetate (EVA) to print flexible electrically conductive parts. EVA graphite composite with filler loading up to 30% has been investigated for its electrical conductivity and part printability. The composite made was found electrically conductive and suitable for part printing. The parts were printed on a CNC milling machine by using a retrofitted material extrusion tool with nozzle of 0.4 mm diameter and temperature range of 130–140°C. Parts were printed on a detchable heating bed placed on the milling machine setup. Samples of EVA with graphite filler by weight of 5%, 10%, 20%, and 30% were printed and were checked for electrical conductivity. When the filler content was increased from 10% to 20%, the electrical resistance of the composite was reduced by 62.6%. The presence and uniform dispersion of graphite flakes in the polymer matrix of EVA were guaranteed by the rheological and morphological characterization of the composite. Applications of 3D printable flexible electrically conductive parts lies in numerous domains including biosensors, wearable health monitoring devices, capacitors, field effective transistors, light emitting diodes, solar cells, and electronic displays.Highlights CNC milling machine‐assisted 3D printing is used for part printing. Graphite powder is combined with EVA pellets. Pellet‐based extrusion is used to print flexible parts. 3D printability of parts with resistivity 32.64 Ω‐cm was achieved.

Расчет коэффициента местного сопротивления при изотермическом течении неньютоновской несжимаемой жидкости в цилиндрическом канале с внезапным сужением

The engineering calculation and construction of the extrusion tool in the form of cylindrical forming channels with sudden narrowing is associated with the determination of the coefficient of resistance of sudden narrowing and local pressure losses. The available theoretical and experimental data on the values of the resistance coefficient of sudden narrowing are contradictory, approximate in nature and, in some cases, do not take into account the rheological properties of the liquid. Their use to calculate local pressure losses under laminar flow conditions leads to significant errors. To eliminate the indicated problems, a mathematical statement of the problem of isothermal stationary laminar flow of non-Newtonian non-compressible fluid in an axisymmetric channel with sudden narrowing was formulated. The mathematical model of flow in spatial formulation is formalized in the form of equations for preserving momentum and mass. As a rheological model, the Carreau model is taken, taking into account the presence of finite viscosity values at marginal shear rates. The numerical solution of the problem was performed by the finite element method using the Comsol MultiphysicsTM CFD modeling package. As a result of the solution, the picture of the current of the non-Newtonian medium was restored in the form of the distribution of current lines, kinematic and dynamic flow parameters. The impact of Reynolds number on change of geometric characteristics of flow structure, kinematic and dynamic flow parameters was evaluated. Values of local resistance coefficient and pressure losses for overcoming sudden narrowing for selected flow modes are calculated. The results of computational experiments are summarized in the form of a criterion ratio for calculating the coefficient of local resistances depending on the Reynolds number.

Review of common hydrogen storage tanks and current manufacturing methods for aluminium alloy tank liners

With the growing concern about climate issues and the urgent need to reduce carbon emissions, hydrogen has attracted increasing attention as a clean and renewable vehicle energy source. However, the storage of flammable hydrogen gas is a major challenge, and it restricts the commercialisation of fuel cell electric vehicles (FCEVs). This paper provides a comprehensive review of common on-board hydrogen storage tanks, possible failure mechanisms and typical manufacturing methods as well as their future development trends. There are generally five types of hydrogen tanks according to different materials used, with only Type III (metallic liner wrapped with composite) and Type IV (polymeric liner wrapped with composite) tanks being used for vehicles. The metallic liner of Type III tank is generally made from aluminium alloys and the associated common manufacturing methods such as roll forming, deep drawing and ironing, and backward extrusion are reviewed and compared. In particular, backward extrusion is a method that can produce near net-shape cylindrical liners without the requirement of welding, and its tool designs and the microstructural evolution of aluminium alloys during the process are analysed. With the improvement and innovation on extrusion tool designs, the extrusion force, which is one of the most demanding issues in the process, can be reduced significantly. As a result, larger liners can be produced using currently available equipment at a lower cost.

3D Bioprinting of Prevascularized Full-Thickness Gelatin-Alginate Structures with Embedded Co-Cultures.

The use of bioprinting allows the creation of complex three-dimensional cell laden grafts with spatial placements of different cell lines. However, a major challenge is insufficient nutrient transfer, especially with the increased size of the graft causing necrosis and reduced proliferation. A possibility to improve nutrient support is the integration of tubular structures for reducing diffusion paths. In this study the influence of prevascularization in full-thickness grafts on cell growth with a variation of cultivation style and cellular composition was investigated. To perform this, the rheological properties of the used gelatin-alginate hydrogel as well as possibilities to improve growth conditions in the hydrogel were assessed. Prevascularized grafts were manufactured using a pneumatic extrusion-based bioprinter with a coaxial extrusion tool. The prevascularized grafts were statically and dynamically cultured with a monoculture of HepG2 cells. Additionally, a co-culture of HepG2 cells, fibroblasts and HUVEC-TERT2 was created while HUVEC-TERT2s were concentrically placed around the hollow channels. A static culture of prevascularized grafts showed short-term improvements in cell proliferation compared to avascular grafts, while a perfusion-based culture showed improvements in mid-term cultivation times. The cultivation of the co-culture indicated the formation of vascular structures from the hollow channels toward avascular areas. According to these results, the integration of prevascular structures show beneficial effects for the in vitro cultivation of bioprinted grafts for which its impact can be increased in larger grafts.

Predictive modeling of extruded filament in the air for bioink in direct ink writing using numerical simulation

Direct ink writing (DIW) is the most widespread 3D printing process for manufacturing parts with bioink. In this paper, a predictive model of extruded filament in the air for bioink in DIW is established using numerical simulation. The predictive model fully considers the complete factors including bioink's material properties, extrusion tool's dimensions and process parameters. This simulation model can be used to predict velocity field and shape of extruded filament in the air which are important parameters for DIW process quality evaluation, control and optimization. The proposed predictive model is then validated through comparison between simulation and experimental results.

Automated Planning for Robotic Multi-Resolution Additive Manufacturing

Abstract Conventional material extrusion additive manufacturing (AM) processes require the user to make a trade-off between surface quality and build time of the part. A large bead filament deposition can speed up the build process; however, it leads to surfaces with high roughness due to the stair-stepping effect. The surface quality can be improved by using a small bead filament deposition, which increases the build time of the part. We present a new approach incorporating hybrid multi-resolution layers in material extrusion additive manufacturing to provide excellent surface quality without increasing the build time. Our slicing algorithm generates planar layers with large filaments to fill the interior regions in less time. The generated exterior layers are conformal and use small filaments to reduce the stair-stepping effect and improve surface quality. We also present a path planning algorithm to build parts with a single manipulator using a multi-nozzle extrusion tool. The path planning algorithm generates a smooth material deposition path by avoiding collision between the tool and the already built layers. It reduces the collision checks and performs collision detection in a computationally efficient manner. We build five parts to validate our approach and illustrate the benefits of multi-resolution AM.

Contribution to process digitisation of cold forging processes using additive manufactured tools

Cold forging tools become increasingly complex and require enhanced functionality, especially in the context of digitisation. Conventional subtractive manufacturing processes often reach their limits when the geometric complexity of the workpiece increases, hence additive manufacturing processes have become increasingly important in the last decades. Additive manufacturing processes have already been used in many fields of manufacturing technology to produce tool components with promising results, but the potentials of additive manufacturing processes have not yet been applied to cold forging tools. Therefore, the Institute for Metal Forming Technology (IFU) of the University of Stuttgart has developed an additive manufactured cold extrusion tool with integrated functional features. As functional features in the additive manufactured extrusion tool, a close contour glass fiber sensor for temperature measurement, a cooling system and a lubrication system for the controlled injection of minimal lubricant amounts during the forming process were integrated. Due to the integrated functional features, structural degradation appears in the tool, therefore the structural-mechanical tool properties were analyzed numerically with the FE-Software DEFORM 3D™ in this report as well. Furthermore, the additive manufactured cold extrusion tool was experimentally evaluated in sequentially executed extrusion operations. Thereby the integrated functional features were used and gathered data were recorded. As a result of the experimental forming tests, near-contour temperature measurements in the extrusion tool with and without the use of the integrated cooling system as well as the modification of the maximum punch forces by an inline lubricant application were obtained. In addition, the experimentally determined temperature fields in the extrusion die are validated with numerically calculated results.

The effect of extrusion direction on the forming quality in CNC incremental forming with multidirectional adjustment of sheet posture

In the CNC incremental forming, the forming quality will be different with the different extrusion direction. The effects of the different extrusion directions on the forming quality in the CNC incremental forming with the multidirectional adjustment of sheet postures were studied by using three extrusion directions: parallel to the Z-axis, perpendicular to sheet surface and perpendicular to the surface to be formed. The algorithm for calculating the inclination angle of the extrusion tool and determining the extrusion direction vector in the multidirectional adjustment environment of sheet postures was presented. The feasibility of the algorithm was verified by an application example. The equivalent plastic strains under the three extrusion directions were analyzed through the numerical simulation. At the same time, the contour accuracy, thickness reduction and thickness distribution were compared and analyzed through the CNC incremental forming experiment with the multidirectional adjustment of sheet postures under the three extrusion directions.

Building free-form thin shell parts using supportless extrusion-based additive manufacturing

Conventional material extrusion additive manufacturing is capable of building complex structures. Overhanging features require the use of support structures. Printing the support structure requires additional time and material. Conventional processes need time to remove support material and may lead to degraded surface finish. The use of support structures can be avoided by dynamically reorienting the build-platform. This paper presents a novel approach to build accurate thin shell parts using supportless extrusion-based additive manufacturing. We describe the layer slicing algorithm, the tool-path planning algorithm, and the neural network-based compensated trajectory generation scheme to use a 3 degree of freedom build-platform and a 3 degree of freedom extrusion tool to build accurate thin shell parts using two manipulators. Such thin shell parts cannot be built without supports by previous supportless AM processes. We illustrate the usefulness of our algorithms by building several thin shell parts.

Research on the CNC incremental forming method based on the surface partition and multi-size extrusion tool head

For the problem that a single-size extrusion tool head cannot meet the high-precision and high-efficiency forming requirement in the CNC incremental forming of the complex-shaped sheet metal parts, a new CNC incremental forming method based on the surface partition and multi-size extrusion tool head is proposed. This method divides the inner surface of the sheet metal parts into the different forming regions according to the curvature of the inner surface, thereby to select the extrusion tool heads with different radius for the different forming regions. That is, the extrusion tool head with large radius is used for the forming region with large curvature radius so as to effectively improve the surface quality and formability of the sheet metal parts, and the small radius of the extrusion tool head is used for the forming region with small curvature radius so as to improve the profile accuracy of the sheet metal parts. The results of the numerical simulation and forming experiment showed that the method can partition the surface of the given sheet metal part and ascertain the corresponding multi-sized extrusion tool heads to the partitioned surface, which can effectively form the complex-shaped sheet metal parts and improve the forming quality and forming efficiency of the sheet metal parts.

The effect of the extrusion direction on the incremental forming quality considering tool deformation

The existing CNC (Computer numerical control) incremental forming mostly adopt the 3-axis CNC incremental forming method whose extrusion direction is always parallel to the Z-axis. However, with the increasing demand for the forming of the complex shape sheet metal part, the researches on the 5-axis CNC incremental forming technology are on the rise, and one of the most important problems in the researches is the reasonable choice of the extrusion direction. To this end, the influence of the extrusion direction on the forming quality was studied. In the actual CNC incremental forming, the deformation of the extrusion tool under the action of the forming force would directly affect the forming accuracy. Therefore, the extrusion tool was regarded as a deformable body and the deformation of the extrusion tool was fully considered in this study, which occurred under the action of the forming force. The numerical simulation and actual forming experiments of the 5-axis CNC incremental forming process were carried out to analyze the effects of the different extrusion directions on the forming quality.

Fatigue–creep interaction based on continuum damage mechanics for AISI H13 hot work tool steel at elevated temperatures

AISI H13 (4Cr5MoSiV1) is one of the commonly used materials for extrusion tool, and it suffers from fatigue–creep damage during the hot extrusion process. Stress-controlled fatigue and creep–fatigue interaction tests were carried out at 500 °C to investigate its damage evolution. The accumulated plastic strain was selected to define the damage variable due to its clear physical meaning. A new fatigue–creep interaction damage model was proposed on the basis of continuum damage mechanics. A new equivalent impulse density for fatigue–creep tests was proposed to incorporate the holding time effect by transforming creep impulse density into fatigue impulse density. The experimental results indicated that the damage model is able to describe the damage evolution under these working conditions.

Product diversification of banana cv. Mas Kirana off grade by using a double rotating screw extruder

Extrusion technology is today’s favorite technology since it has a varied, practical and consistent product form. The purpose of this research was to get precise composite flour composition so that the quality of the resulted product has optimum quality for breakfast meals. The experimental design used was Design Expert vs. 7 with response surface box-behnken. The flour composition and level to be inputted to the program were banana flour (10-50g), mung beans (10-30g), egg flour (10-20g). Formula made was based on 200 g with addition of maize flour if the amount is less than 200 g. The extrusion tool used is a Thermo Scientific double rotating screw; with Haake Reomax OS. The best results in terms of carbohydrate content is the Formula 8 with a composition of 60 g of banana flour, 20 g eggs, 20 g of green beans and 100 g maize flour. The proximate chemical content of this formula is carbohydrate 84.04%, protein 8.55%, fat 5.49%, ash content 1.24%. K-calories per 100 g is 419.5 which is higher than the standard of breakfast meals calories.

A mean plastic strain fatigue–creep life prediction and reliability analysis of AISI H13 based on energy method

Abstract

5-Axis CNC incremental forming toolpath generation based on formability

To the problem of the existing CNC incremental forming that mostly adopts the 3-axis CNC incremental forming method and cannot form the complex sheet metal part containing the surface by one-stage forming, which cannot be visible in the positive and negative directions of the Z-axis and whose forming angle is larger than 90°, a multi-directional slant and multi-directional pressing toolpath generation method for the 5-axis CNC incremental forming was proposed to accomplish the forming of the complex sheet metal parts by fully considering the differences of the forming angles at each position of the surface and the accessibility of the extrusion tool to the surface. In this method, the posture of the forming toolpath is adjusted individually according to the forming angle at each position of the surface so that the posture of the sheet metal is constantly adjusted in the forming process, which ensures all the forming angles of the surface to be less than the forming limit angle. Moreover, the posture of the extrusion tool is also adjusted according to the accessibility of the extrusion tool to the surface and the features of the surface, which makes the extrusion tool to press the sheet metal along the needed directions so as to control the deformation state and material flow efficiently, and then accomplish the forming of the complex sheet metal part. The results of the research show that the 5-axis CNC incremental toolpath generated based on the method mentioned earlier can form the complex sheet metal part containing the surfaces whose forming angle is larger than 90° and that is invisible from the positive and negative directions of Z-axis.

THE EFFECTS OF THE DIE HALF ANGLE OF TAPER DIE ON PLANE STRAIN EXTRUSION

In this research, a study of the effect of a die half angle on the extrusion process has been performed. The experiments were conducted at room temperature around 27 °C. Two types of taper die with different die half angles (45° and 60°) were prepared. The test lubricants used were paraffinic mineral oil VG460 and Refined, Bleached and Deodorized (RBD) Palm stearin. The material of the workpiece (billet) was annealed with A1100 aluminium. The experimental results were focused on the extrusion load, tool and workpiece surface roughness and plastic deformation of the workpiece. The resultant relative velocity was calculated using a visioplasticity method. The results shows that a taper angle of 60° recorded higher resultant relative velocity with a lower extrusion load and surface roughness compare to the taper angle of 45°. The comparison study between Paraffinic Mineral Oil and RBD Palm Stearin shows no significant effect in both taper angles tested.