Extruder Design Research Articles

Design and Development of Plastic Filament Extruder for 3D Printing

<p>3D printing is a form of additive manufacturing technology where a three dimensional object is created by laying down successive layers of material. It is mechanized method whereby 3D objects are quickly made on a reasonably sized machine connected to a computer containing blueprints for the object. As 3D printing is growing fast and giving a boost to product development, the factories doing 3D printing need to continuously meet the printing requirements and maintain an adequate amount of inventory of the filament. As the manufactures have to buy these filaments from various vendors, the cost of 3D printing increases. To overcome the problem faced by the manufacturers, small workshop owners, the need of 3D filament making machine arises. This project focuses on designing and fabricating a portable fused deposition 3D printer filament making machine with cheap and easily available components to draw 1.75 mm diameter ABS filament.</p>

Parametric analysis and design of a screw extruder for slightly non-Newtonian (pseudoplastic) materials

Extruders have found application in the food, polymer and pharmaceutical industries. Rheological characteristics of materials are important in the specification of design parameters of screw extruders. Biopolymers, which consist of proteins, nucleic acids and polysaccharides, are shear-thinning (pseudoplastic) within normal operating ranges. However, analytical models to predict and design screw extruders for non-Newtonian pseudoplastic materials are rare. In this study, an analytical model suitable to design a screw extruder for slightly non-Newtonian materials was developed. The model was used to predict the performance of the screw extruder while processing materials with power law indices slightly deviating from unity (the Newtonian case). Using non-dimensional analysis, the effects of design and operational parameters were investigated. Expressions to determine the optimum channel depth and helix angle were also derived. The model is capable of predicting the performance of the screw extruder within the range of power law indices considered (1/2⩽n⩽1). The power law index influences the choice of optimum channel depth and helix angle of the screw extruder.

Design and development of an extrusion system for 3D printing biopolymer pellets

The extrusion system is an integral part of any fused deposition style 3D printing technique. However, the extruder designs found in commercial and hobbyist printers are mostly suitable for materials in filament form. While printing with a filament is not a problem per se, the printing of materials that may not be readily available in the filament form or not commercially viable remains untapped, e.g., biopolymers and material blends. This is particularly an issue in the research and hobbyist space where the capability of printing a variety of materials or materials recycled from already printed parts may be of utmost importance. This paper presents a pellet-based extrusion system for the 3D printing of biopolymers. The system has been designed from the first principles and therefore can be extended to other materials with parameter adjustments or slight hardware modifications. A robust mechatronic design has been realized using an unconventional yet simplistic approach. The extrusion system uses a series of control factors to generate a consistent output of material over the course of a print. The platform and surrounding processes are set up so that software can be used to define the printing parameters; this allows a simpler adaption to different materials. The utility of the extruder is demonstrated through extensive printing and testing of the printed parts.

Optimization and Numerical Simulation of Outlet of Twin Screw Extruder

In view of the unreasonable design of non-intermeshing counter-rotating twin screw extruder die, the problem of productivity reduction was discussed. Firstly, the mathematical model of extruder productivity was established. The extruder die model was improved. Secondly, the force analysis of twin screw extruder physical model was carried out. Meanwhile, A combination of mechanical analysis and numerical simulation was adopted. The velocity field, pressure field and viscosity field were calculated by Mini-Element interpolation method, linear interpolation method and Picard iterative convergence method respectively. The influence of die model on the quantity of each field before and after improvement was analyzed. The results show that the improved model had increased the rheological parameters of the flow field, the leakage and reverse flow decreased. Through post-processing calculation, the productivity of the third dies extruder was 10% higher than before. The research results provide a theoretical basis for the design and optimization of die model of non intermeshing counter-rotating twin screw extruder.

Hot-Melt Extrusion Technology in the Emerging Pharma Field

After the plastic industry, now in Pharmaceutical industry hot melt extrusion (HME) technology has emerged and has made its way for the easy development of the pharmaceutical products due to its severe advantages like free of solvents, faster processing technology, operation in simple and continuous process, and high degree of automation, are few among them over to the other conventional methods. Day by day the interest on HME technology has been increasing due to its promising approach towards the drug delivery systems. The gradual increase in the patents of HME technology will enlighten us the need of it in this field of medicines. This article mainly reviews the general design and construction of hot melt extruder along with the advantages, disadvantages and applications of the HME.

Modelling of paste ram extrusion subject to liquid phase migration and wall friction

Extrusion of solid-liquid particulate pastes is a well-established process in industry for continuously forming products of defined cross-sectional shape. At low extrusion velocities, the solids and liquid phases can separate due to drainage of liquid through the interparticle pores, termed liquid phase migration (LPM). The effect of wall friction, die shape and extrusion speed on LPM in a cylindrically axisymmetric ram extruder is investigated using a two-dimensional finite element model of paste extrusion based on soil mechanics principles (modified Cam-Clay). This extends the smooth walled model reported by Patel et al. (2007) to incorporate a simplified Tresca wall friction condition. Three die entry angles (90°, 60° and 45°) and two extrusion speeds are considered. The extrusion pressure is predicted to increase with the Tresca friction factor and the extent of LPM is predicted to increase with decreasing ram speed (both as expected). The effects of wall friction on LPM are shown to be dictated by the die shape and ram displacement: there are few general rules relating extruder design and operating conditions to extent of LPM, so that finite element-based simulation is likely to be needed to predict the onset of LPM accurately.

Parametric analysis and design of straight screw extruder for solids compaction

Screw extruders are commonly used in the food and polymer industries. Scientifically designed screw extruders for biomass compaction equipment are required to limit the existing problems faced in the industry. In this study, models based on the plug flow theory were developed and used to analyse the screw extruder for biomass compaction. The approach for development of the plug flow model involves a traction-and-retardation based mechanism utilizing force balances only, in contrast to the force and torque balance of previous models. The pressure developed along the length of the screw extruder was exponential and affected by the friction coefficients at biomass material interfaces between the screw and barrel, the channel depth and helix angle. The movement of material in the compaction region is drag-induced and the screw speed, channel depth and helix angle determine the flow rate through the screw channel. The approach utilized in this study for the development of models could be extended to study other types of screw extruders with relative ease compared to earlier approaches based on the plug flow theory.

Time‐ and State‐Dependent Input Delay‐Compensated Bang‐Bang Control of a Screw Extruder for 3D Printing

SummaryIn this paper, a delay‐compensated bang‐bang control design methodology for the control of the nozzle output flow rate of screw extruder‐based three‐dimensional printing processes is developed. A geometrical decomposition of the screw extruder in a partially and a fully filled regions allows to describe the material convection in the extruder chamber by a one‐dimensional hyperbolic partial differential equation (PDE) coupled with an ordinary differential equation. After solving the hyperbolic PDE by the method of characteristics, the coupled PDE–ordinary differential equation's system is transformed into a nonlinear state‐dependent input delay system. The aforementioned delay system is extended to the non‐isothermal case with the consideration of periodic fluctuations acting on the material's convection speed, which represent the process variabilities due to temperature changes in the extruder chamber, resulting to a nonlinear system with an input delay that simultaneously depends on the state and the time variable. Global exponential stability of the nonlinear delay‐free plant is established under a piecewise exponential feedback controller that is designed. By combining the nominal, piecewise exponential feedback controller with nonlinear predictor feedback, the compensation of the time‐dependent and state‐dependent input delay of the extruder model is achieved. Global asymptotic stability of the closed‐loop system under the bang‐bang predictor feedback control law is established when certain conditions related to the extruder design and the material properties, as well as to the magnitude and frequency of the materials transport speed variations, are satisfied. Simulations results are presented to illustrate the effectiveness of the proposed control design. Copyright © 2017 John Wiley & Sons, Ltd.

Substantiation of design parameters of extruder and determination of extrudate quality

The article reviews the designs of extruders and screws. It describes the main known methods of determination of material quality. As a technical solution improving the design of extruder, a double-threaded screw that should be installed in the material forming zone is proposed.

Diagnostic Twin Screw Extruder: Initial Measurements of Continuous Ne, H2, and D2 Extrusions

Flow and heat transfer measurements of solid hydrogenic materials inside twin screw extruders are not available. Fusion tokamaks like ITER require fuel pellet injection at 99.9% reliability which requires validated twin screw extruder throughput models for operation. The throughput of an extruder is limited by the amount of leakage flow through clearance gaps which depends on flow properties that vary strongly with temperature for hydrogenic materials. A Diagnostic Twin Screw Extruder (DTSE) has been built to measure azimuthal and axial temperature distributions as well as torque, cooling power, and screw speed for H2, D2, and Ne extrusions. In this paper the experimental procedure for the DTSE is described and azimuthal temperature measurements at three locations along the screws are discussed. The results show variations in temperature as large as 0.5 K azimuthally and >0.5 K axially. The overall temperatures stay close to the solidification temperature and therefore support high backflow and explain extrudate stall scenarios experienced in other hydrogenic twin screw extruders. This temperature data is therefore useful to size tolerance gaps in future extruder designs and enables refinement of predictive models for continuous operation.

Polyester fiber production using virgin and recycled PET

In this study, the design and construction of an extrusion equipment with spinning fiber devices has been developed to produce polyester fiber from virgin and recycled polyethylene terephthalate (PET). Several operating parameters (i.e., pressure, temperature, feed flow rate, extrusion speed and extruder design) have been analyzed to identify the best process conditions. In particular, this study has focused on a detailed analysis for the processing of recycled raw material for polyester textile fiber applications considering the variability of the process and identifying alternatives to minimize the impact on the quality parameters such as the fiber diameter and mechanical specifications. The experimental results were compared with the values calculated using a theoretical model, which has been developed for these particular cases. The mathematical analysis of the mass flow showed a very good agreement with respect to the experimental data, where there was a percentage difference < 3 %. It was found that the fiber diameter is a function of intrinsic viscosity (VI) or melt flow index (MFI). Finally, the mechanical properties of the fibers were evaluated and results indicated that the fiber with higher average molecular weight showed higher tenacity and lower Young’s modulus values.

Study of the Technical Feasibility and Design of a Mini Head Screw Extruder Applied to Filament Deposition in Desktop 3-D Printer

The purpose of this work is to present the study of the technical feasibility and functional design of an interchangeable mini head extruder based on a screw with variable section to be used in open-source desktop 3-D printers. The QFD matrix was used during the design planning where the non-commercial users’ requirements were established. Functional structure of the mini head extruder was organized to give support to the mechanical calculation. The choice of a feasible configuration allowed the pre-calculation of the main components of the proposed head which were: screw, barrel and motor system. The materials chosen for the mechanical and rheological calculations were polyamide and the biopolymer PCL, both in powder distribution. Apart from the mechanical design, supported by the QFD, and functional analysis, the mini head extruder was manufactured and assembled, showing its functionality to generate filaments with diameter of 0.7 mm from powder raw material. The complete mechanical and electrical design development and manufacturing of this mini head extruder were made in a period of 24 months. This systematic development demonstrated the importance of the design methodology during the development of the design process and its contribution to the design quality. Besides, the mini head extruder using screw will allow the generation of scaffold structures using biopolymers, as well as to enable comparative studies using different kind of polymers.

Development of a Diagnostic Twin Screw Extruder to Characterize Fuel Production for Tokamaks

Twin screw extrusion is anticipated to meet the pellet fueling demands of tokamak fusion devices. The twin-screw design principle has been proven by a functional prototype extruder at Oak Ridge National Laboratory (ORNL); however numerical models necessary for design optimization have yet to be validated due to system complexity. Characteristic measurements of solid flow during extrusion are difficult for any extruder and are exacerbated by the cryogenic environment necessary to solidify solid hydrogen. In this paper, we first discuss current modeling efforts to establish needs for experimental measurements and then present the design and construction status of a diagnostic twin-screw extruder to address these needs. Development is underway of a mass transfer analysis that predicts volumetric efficiency and augments an existing 1st order model of extrudate temperature. These predictive models are necessary for design and operation of hydrogenic twin screw extruders for fueling tokamaks, including ITER.

Upscaling of the hot-melt extrusion process: Comparison between laboratory scale and pilot scale production of solid dispersions with miconazole and Kollicoat® IR

Since only limited amount of drug is available in early development stages, the extruder design has evolved towards smaller batch sizes, with a more simple design. An in dept study about the consequences of the differences in design is mandatory and little can be found in literature. Miconazole and Kollicoat® IR were used as model drug and carrier for this study. Two series of solid dispersions were made with a laboratory scale (internal circulation-simple screw design) and a pilot scale extruder (continuous throughput-modular screw design). Efforts were made to match the operating parameters as close as possible (residence time, extrusion temperature and screw speed). The samples were analyzed with modulated DSC straight after production and after exact 24h and 15days storage at −26°C. The kinetic miscibility of the samples prepared with the laboratory scale extruder was slightly higher than the samples prepared with the pilot scale extruder. As the solid dispersions with high drug load were unstable over time, demixing occurred, slightly faster for the samples prepared with the laboratory scale extruder. After 15days, the levels of molecular mixing were comparable, pointing to the predictive value of samples prepared on laboratory scale.

Study on 3D CAD System of Extruder

The extruder is the key device to produce extrusion feed and food. Since different raw materialsi require different structural and technological parameters, the parametric design method must be used when an extruder is designed. The 3D (3-dimensional) software now available is just universal design platform, so the further development must be done based on universal software to realize the automatic design of machines for special purpose. In this paper the further development is carried out and the CAD (Computer Aided Design) system for the 3D parametric design of extruder is developed based on Solidworks. The system is developed with Visual C++, and it can be compatibly added in Solidworks as dynamic linkage library, which makes the modification of extruder more rapid and more correct. The paper introduces every function part in detail, including parameter input , design and calculation, 3D modeling of part, 3D modeling of assembly, engineering drawing. The realization of the automatic 3D modeling adopts the new idea of driven by dimension primarily and driven by program secondarily. The whole system is encapsulated in a menu of Solidworks. After some parameters, such as power and rotational speed, are imported through UI (User Interface), the system will automatically complete the design of extruder. Then 3D models and engineering drawings of parts or assembly can be exported according to the choice of user.

The Modular Design of Cold Feeding Rubber Extruders

The conception of the modular design is introduced in design and manufacture of cold feeding rubber extruders; and the realization of process is expounded in details. It improves design efficiency and product quality significantly, and meets the needs of the time.

Studies on positive conveying in helically channeled single screw extruders

A solids conveying theory called double-flight driving theory was proposed for helically channeled single screw extruders. In the extruder, screw channel rotates against static barrel channel, which behaves as cooperative embedded twin-screws for the positive conveying. They turn as two parallel arc plates, between which an arc-plate solid-plug was assumed. By analyzing the forces on the solid-plug in the barrel channel and screw channel, the boundary conditions when the solid-plug is waived of being cut off on barrel wall, were found to have the capacity of the positive conveying. Experi- mental data were obtained using a specially designed extruder with a helically channeled barrel in the feeding zone and a pressure-adjustable die. The effects of the barrel channel geometry and friction coefficients on the conveying mechanism were presented and compared with the experimental results. The simulations showed that the positive conveying could be achieved after optimizing extruder designs. Compared with the traditional design with the friction-drag conveying, the throughput is higher while screw torque and energy consumption are decreased. Besides, the design criteria of the barrel channel were also discussed.

Rheological Modeling and Dynamic Characteristics of Disc Extruders

Abstract Disc extruders have been employed for blending, mixing, dispersing, coloring, homogenizing, degassing, and granulating of polymers. One of the difficulties in the design of disc extruders is the evaluation of dynamic characteristics such as required power, momentum transfer rate, and applied torque, which indeed indicates the capability of the machine and its components. In this paper the required conditions and model for developing of elastic deformation of polymers in the disc extruders are studied. By rheological modeling of disc extruders and related elements, dynamic behavior of this processing system which highly depends on elastic properties of polymeric materials is obtained. These data are necessary for a proper design the system, and more accurate calculation its moving parts.

Wytlaczanie dihelikoidalne. Podstawy i realizacja

The principle of the dihelicoidal extrusion process based on a rotational middle segment of the single-screw barrel of an extruder (Fig. 1) has been presented. This active component design makes it possible for changes in the process parameters to be made without having to halt the equipment. The fundamentals of the process and the design of the dihelicoidal extruder were also discussed. A simplified model (Fig. 2) as well as a functional version (Fig. 6) of the extruder illustrating the active feed zone (Fig. 7) and the active compatible rotational segment of the barrel (Fig. 8) were described in detail. The performance of such a new dihelicoidal extruder was verified with selected results obtained in experimental studies.

Study on Modification of the Banana Peel in the Extrusion

Using self-determined design of SPJ-40 experimental twin-screw extruder to extrude the banana peel is investigated in this study. Results revealed that the best extrusion conditions were: banana peel and starch at rate of 2:8, feed moisture at 16%, screw speed at 268r/min, extrusion temperature at 150°C, and feeding rate at 20r/min. The structures of the products were determined after the extrusion. The electron microscopy showed that the structure of the starch powders and fibers had been greatly damaged, leading to the great increasing of surface area of processed products. Compared to the raw material, the crystallinity of products was down to 13.06% from 19.85%, but soluble dietary fiber was increased by 30.3 percent. The final product tastes delicate with palatable aroma. Overall, this extrusion technology for processing banana peel has bright prospect in application.