Goal[edit | edit source]
The main goal of this literature review is to define a standardized step-by-step procedure for designing a twin-screw extruder. This page is dedicated to Fast's plastic waste to food project under supervision of Prof.Joshua M Pearce.
Concepts[edit | edit source]
The twin-screw extruder is composed of the following components: hopper, barrel, variable screw speed and temperature control, electrical motor, and replaceable dies for producing products with varying sizes and forms. The schematic diagram of a twin-screw extruder is illustrated in figure 1.
Background[edit | edit source]
Summarize: Schneider  historically reviewed the evolution progress of the counter-rotating twin-screw extruder, which was originally developed in the early 1950s by Anton and Wilhelm Anger, who built a twin-screw extruder with a length of 12*D by overcoming the problem of joining pipes by means of plastic. After two decades of advancement in twin-screw extruder technology, the two most active companies namely Thyssen and Rheinstahl merged in 1972 and Thyssen Plastik Maschinen (TPM) was started its work by developing a new parallel model of twin-screw extruder series in 1976 with screw diameters of 50, 60, 85, 107, 130 as well as 160 mm. To resolve the issue of safely, adjusting the radial and axial forces in parallel models, and conical twin-screw extruders were developed that had design benefits for shaping the distributor drive. The first model was designed by Anger (AGM) in 1964, which was called single conical screws. A double conical screw was introduced by Krauss-Maffei In 1974, in which the flight depth declines constantly from the feed section to the metering section, and consequently, the output rate will increase. A little later, Krauss-Maffei proposed a multi-screw extruder in 1974, which was suitable for producing large pipe with approximately output rates ranged from 800 to1000 kg/h. Some multi-screw designs were invented by combining two pairs of screws as one twin-screw. Smaller screw diameters provide a greater percentage of surface area to throughput, allowing a great heated energy to be input from the outside. Throttle designs were developed to provide better material compression in addition to heat and shear energy input. Six brand new parallel twin-screw extruders with diameters ranging from 50 to 160 mm were presented in 1976. The profile screws, rather than the breaker plate, were outfitted with a double flighted, closely intermeshing throttle, and the pelletizing and pipe screws were equipped with baffles.
Key technological advances of extrusion processing[edit | edit source]
Summarize: Emin  studied the state of art technological developments of extrusion processing that have a valuable place in food industries due to its flexibility for utilizing various raw materials for producing adaptable food products. The studies on this process are mainly divided into two essential sections including screw and die, which are concerned with extruded raw material and giving the desired shape and texture to the products. After these two sections, a product will be ready to eat by customers. For ensuring the quality of the designed products, some analyses include reaction properties and rheological properties were conducted. In the reaction properties analysis, not only the molecular interactions are considered but also some factors including temperature, time, shear stress, components, mixing ratio, and water content is considered. In the rheological properties, blending properties, thermal and mechanical stress profile in the screw section, or expansion and texturizing in the die section are examined. Analysis of processing conditions is another critical step that includes thermal stress profile analysis, and thermomechanical stress profile and mixing characteristics analysis. For the first analysis (thermal stress profile), it is very essential to gather some information regarding the temperature of the material and its residence time. For the later one (thermomechanical stress profile and mixing characteristics), numerical analysis mainly finite element method (FEM) using FEM code ANSYS POLFLOW is performed to obtain essential information about thermomechanical stress profile and mixing characteristics. The gathered information then can be used to adjust the process to precisely perform a process to obtain the desired product or to achieve products in different preferred scales.
Extrusion-based food printing for digitalized food design and nutrition control[edit | edit source]
Summarize: Sun et al.  reviewed the published works in the context of "food printing via extrusion techniques" to identify the problems and developments in this research area. The multi-axis configurations including Cartesian, Delta, Polar and Selective Compliant Assembly Robot Arm (Scara) are mainly used in the food printing procedure. The Cartesian structure has X, Y, and Z axes for left-to-right, front-to-back, and up-and-down movement. In the Delta, a circular print stage is installed, and the print head is placed over it by three triangle arms. A Polar food printer includes a rotating stage as well as a print head that can move up and down to cover the Z-axis and left and right to cover the X and Y axes tangentially. SCARA configuration consists of a robot arm that moves in the X-Y plane and an extra actuator that moves along the Z-Axis. Because of the higher proportion of printed nourishment component volume to printer size, shorter production time, and lower cost, a rising interest in designing printers with Delta or Polar structures is found. Although printing accuracy is important for consistent and repeatable fabrication, it is typically less demanding in food printing than in plastic printing or medical printing. In various designed food printers, three extrusion mechanisms including syringe, air pressure, and screw are used. The syringe-based extrusion unit consists of a syringe for storing feeding supplies and a step engine to power the extrusion operation. A pneumatic pump and an encapsulated food cartridge comprise an air pressure-driven extrusion device, with the pneumatic pump pushing the material within the encapsulated food cartridge out of the nozzle. Food materials are loaded into the cartridge and transferred to the nozzle by an auger screw in screw-based extrusion for continuous printing.
Summarize: Justino Netto and Silveira  proposed a methodical procedure technique for co-rotating twin screw extruder segments that provide valuable information to design an interchangeable printing head in Additive Manufacturing. Their results showed that the screws can rotate properly without fault and the material is transferred as predicted towards the die. Their method relies on designing a micro twin screw extruder intended to process small volumes of powder material (around 100 g) according to Pahl et al.  , which the design process includes per-dimensioning comes after the information gathering and conceptual design steps. After the assurances of the standard model configuration, the design's aspects include dimensions and tolerances, manufacturing procedures, and prices were finalized.
Note 1:To boost velocity steadily along the flow channel, fundamental aspects must be considered during die design for avoiding dead spots, therefore flow resistance parameter (Kp) was calculated by Equation 13 in their paper.
Note 2: Their findings showed that the developed design approach is appropriate for utilizing as a polymer compounding mini extruder and 3D print head.
Summarize: Kumar et al.  built an extrusion system for producing filament from recyclable plastics, which is a vital part of 3D printer designing. In this work, an expulsion machine was constructed to generate 3D printing fiber from PET bottle pellets. The final design was a low-cost, high-performance machine that shreds, dissolves, and mixes polyethylene terephthalate plastic water bottles after expelling them as homogenous fiber. The main procedure of the designed extrusion system contains a screw that transfers recyclable plastic pellets from a holder through a warming spot in a metal line where the plastic is liquefied by high thermal temperature. Then, the liquified plastic pellets are moved into the screw from the holder to compress through a spout toward the end of the line to frame a fiber. The extrusion process has five individual stages including installing extruder nozzle, material temperature fixing, feed hopper, guide filament, and measuring the diameter of filament, in which the temperature can change to achieve distinct sizes of filament. The design process was performed in seven phases including barrel, hopper, nozzle, screw rod, shredder blade, shredder casting, and extrusion assembly. Their results showed that optimum outcome can be achieved by fixing the temperature ranges between 230-250°C and a high-efficiency rate can be achieved by decreasing the heat conduction. With a higher separation between the container and the warm zone, a larger volume of plastics may be included, allowing the extruder to discharge more fiber without the risk of blocking the delta of the warming line.
A comparative study between syringe-based and screw-based 3D food printers by computational simulation[edit | edit source]
Guo et al. arranged computational research to study the difference between syringe-based and screw-based 3D food printers, which two mainly used Extrusion-based 3D in the food industry. the computational fluid dynamics (CFD) models were discussed in this study to assess and compare the fluid characteristics of two types of 3D printing. Also, an experimental 3D printing evaluation was performed to compare two different 3D food printers. The CFD simulations were carried out using the COMSOL Multiphysics computer software, which is a commercially available FEM-based computer program. The rotating machinery and laminar flow characteristics of the CFD Module were used in this study to address the fluid characteristic within the screw-based extrusion 3D printing and the syringe-based extrusion 3D printing hardware, respectively. Ink for 3D printing was made from mashed potatoes. Throughout the experiment, the temperature remained constant at 26 degrees Celsius. The fluid was considered to be a single-phase incompressible fluid with a laminar flow interface.
Note: A simulated model investigation revealed that the 3D food printer via screw had a complicated fluid characteristic, with a few backflows discovered at the gap between the walls and the screw flights in the extrusion tube. The syringe-based 3D food printer, on the other hand, looked to have more basic fluid characteristics that could be easily changed. Further, the experimental 3D printing suggested that screw-based 3D food printers were inappropriate for extruding viscous inks. The current study provides data for proper printing strategy selection, a theoretical foundation, and a specialized guide for advanced 3D printing research and modern printer design.
Design[edit | edit source]
Design 1:[edit | edit source]
Summarize: This design procedure was used by Sobowale et al.  to fabricate a twin screw extruder.The extruder was designed to resolve all the problems mentioned in the construction of a twin screw extruder conducted by Senanayake and Clarke  and Yamsaengsung and Noomuang . In this work, the performance of the designed extruder was investigated using various instruments including cocoyam flour, varying feed moisture content (FMC), and screw speed (SS). Various factors such as expansion ratio , residence time (RT), throughput, and functional efficiency were analyzed to ensure that all parts of the extruder are suitably assembled and work properly with high efficiency. The constructed extruder operated admirably, with products expanding quite well. Except for the discoloration of the cocoyam extrudate at increased temperatures, which resulted in an undesirable product, there were no serious issues during the operation. This finally influenced the barrel temperature and FMC used, and it is suggested that cold extrusion is more appropriate for the cocoyam extrudate. By inserting a replacement die unit of various forms into the machine, tests on the equipment proved its capabilities as a multifunctional extruding machine generating numerous expelled items of diverse shapes and sizes.
Calculations[edit | edit source]
|Parameter||Symbol||Unit||Assumptions||Formula in Sobowale et al.  study|
|Length of screw||L||mm|
|Length of barrel||Lb||mm|
|Height of beam||Ymax||mm|
|Thickness of beam||b||mm|
|Face length of beam||I||mm|
|Diameter of initial pitch circle||Po||mm|
|Total power consumption||Pt||kW|
|Part of the power consumption for viscous dissipation related to shear of the feed||Ps||kW|
|Screw power number||Np||rpm|
|Driven pulley diameter||D2||mm|
|Driven pulley diameter||D1||mm|
|Driven pulley speed||N1||rpm|
|Driven pulley speed||N2||rpm|
|Length of barrel||B1||mm|
|Radial flight clearance||δf||%|
|Inside diameter of the extruder barrel||Db||mm|
|Helix angle at the root of the screw||θs||Degree o|
|Helix angle at the root of the bolt||θb||Degree o|
|Channel width at the root of the screw||Ws||mm|
|Channel width at the root of the bolt||Wb||mm|
|Weight of the pulley||Wp||N|
|Mass of the pulley||Mp||kg|
|Gravity of earth||g||m/s^2||9.81|
|Volume of the hopper||V||m3|
|Variation in shaft radius||Δr||mm|
|Allowable shear stress for shaft||T||N.m|
|Mass flow rate||m||Kg/hr|
|Channel depth of metering zone||Hm||mm|
|Relative density(Specific gravity)||G||-|
|Dynamic bearing capacity of thrust bearing||Creq||kN|
|Sense rotation factor||fd||-|
|Thrust pressure from extruder||Fax||kN|
|Life of bearing||Lf||hr|
References[edit | edit source]
- Schneider, Hans-Peter (2005). "The historical development of the counter-rotating twin-screw extruder". Kunstoffe Plast. Eur 1: 1–6.
- Emin, M. Azad (2022-01-01). "7 - Key technological advances of extrusion processing". In Pablo Juliano, Roman Buckow, Minh H. Nguyen, Kai Knoerzer, Jay Sellahewa (eds.). Food Engineering Innovations Across the Food Supply Chain. Academic Press. pp. 131–148. ISBN 978-0-12-821292-9. Retrieved 2022-01-11.
- Sun, Jie; Zhou, Weibiao; Yan, Liangkun; Huang, Dejian; Lin, Lien-ya (2018-03-01). "Extrusion-based food printing for digitalized food design and nutrition control". Journal of Food Engineering. 3D Printed Food – Design and Technology 220: 1–11. doi:10.1016/j.jfoodeng.2017.02.028. ISSN 0260-8774. Retrieved 2022-01-11.
- Silveira, Zilda de Castro; Justino Netto, Joaquim Manoel (2017). "ON THE DESIGN AND TECHNOLOGY OF CO-ROTATING TWIN SCREW EXTRUDERS". Anais do IX Congresso Brasileiro de Engenharia de Fabricação. Congresso Brasileiro de Engenharia de Fabricação. ABCM. doi:10.26678/ABCM.COBEF2017.COF2017-0017. Retrieved 2022-01-11.
- Pahl, Gerhard; Beitz, Wolfgang; Feldhusen, Jörg; Grote, Karl-Heinrich (2007). "Product Development Process". In Gerhard Pahl, Wolfgang Beitz, Jörg Feldhusen, Karl-Heinrich Grote (eds.). Engineering Design: A Systematic Approach. London: Springer. pp. 125–143. ISBN 978-1-84628-319-2. Retrieved 2022-01-11.
- Kumar, Sagar; Sooraj, R.; Kumar, M. V. Vinod (2021-02). "Design And Fabrication Of Extrusion Machine For Recycling Plastics". IOP Conference Series: Materials Science and Engineering 1065 (1): 012014. doi:10.1088/1757-899X/1065/1/012014. ISSN 1757-899X. Retrieved 2022-01-11.
- Guo, Chao-Fan; Zhang, Min; Bhandari, Bhesh (2019-07-01). "A comparative study between syringe-based and screw-based 3D food printers by computational simulation". Computers and Electronics in Agriculture 162: 397–404. doi:10.1016/j.compag.2019.04.032. ISSN 0168-1699. Retrieved 2022-01-11.
- Sobowale, S. S.; Adebo, O.; Adebiyi, J. A. (2018). "Development of a twin screw extruder". Retrieved 2022-01-09.
- Senanayake, S. A. M. A. N. S; Clarke, B (1999-05-01). "A simplified twin screw co-rotating food extruder: design, fabrication and testing". Journal of Food Engineering 40 (1): 129–137. doi:10.1016/S0260-8774(99)00049-7. ISSN 0260-8774. Retrieved 2022-01-09.
- Yamsaengsung, Ram; Noomuang, Chumporn (2010). Finite Element Modeling for the Design of a Single-Screw Extruder for Starch-Based Snack Products. pp. 5.
- Jr, Harold F. Giles; III, Eldridge M. Mount; Jr, John R. Wagner (2004-12-31). Extrusion: The Definitive Processing Guide and Handbook. William Andrew. ISBN 978-0-8155-1711-5.
- Gupta, RS Khurmi (2005). A Textbook of Machine Design. S. Chand Publishing. ISBN 978-81-219-2537-2.
- Singh, R. Paul; Heldman, Dennis R. (2001-06-29). Introduction to Food Engineering. Gulf Professional Publishing. ISBN 978-0-08-057449-3.
- "Design and Performance Evaluation of a Melon Sheller - Sobowale - 2016 - Journal of Food Process Engineering - Wiley Online Library". Retrieved 2022-01-09.
- Sobowale, Sunday Samuel; Adebiyi, Janet Adeyinka; Adebo, Oluwafemi Ayodeji (2017). "Design, construction, and performance evaluation of a gari roaster". Journal of Food Process Engineering 40 (3): –12493. doi:10.1111/jfpe.12493. ISSN 1745-4530. Retrieved 2022-01-09.