A filament extrusion system and a method for producing filaments

Abstract

The invention provides a filament extrusion system for producing thermoplastic filaments with precise dimensional control. The system includes an extrusion unit having a vertically oriented screw extruder fed by a hopper with a funnel geometry and internal baffles for improved mixing and flow. A motor, coupled to the screw via a double coaxial thrust bearing assembly, drives the screw within a barrel having multiple heating zones and a pineapple-cut mixing section. Melted material is extruded through a nozzle, cooled in a cooling zone, and measured by a downstream diameter sensing unit. A puller unit, operating under closed-loop feedback from diameter measurements, adjusts speed to maintain a predefined filament diameter. A spooling unit collects the filament, and all components are supported on a main frame, enabling consistent, high-quality filament production with controlled extrusion, cooling, measurement, pulling, and winding functions. Figure 2 is the representative figure.

Description

FIELD OF THE INVENTION

[001] The present invention relates to a filament extrusion system and a method for producingfilaments, more particularly the present invention relates to the filament extrusion system andthe method for producing filaments for maintaining dimensional accuracy and quality ofextruded filaments.BACKGROUND OF THE INVENTION

[002] Filament production for Filament Fabrication (FFF) or 3D printing a technology basedon the extrusion of material, typically a polymer, to form parts. FFF involves melting plasticfilament onto a print surface, where the plastic filament solidifies upon cooling to form threedimensional objects through the deposition of multiple layers. This technique was originallymeant for building prototypes; however, the technique is currently used to build finalcomponents. In FFF printers, material is heated, melted, and pushed by a feed system and thenforced through a nozzle. At a constant pressure, the extruded material will flow at a constantrate and have a constant cross-section diameter. This stock material is usually an amorphousthermoplastic in the form of a filament, that solidifies after being deposited in the buildplatform. This technology is becoming available in both professional and privateenvironments.

[003] FFF is currently dependent on industrial-scale extrusion facilities that manufacturestandardized thermoplastic filaments. This increases the cost for end-users and limits theirability to experiment with new materials or recycle waste. Furthermore, failed prints andleftover parts often go unused, contributing to material wastage. Therefore, there is a growingneed for a compact, low-cost, and user-friendly solution that allows individuals or small labsto produce their own filament in-house. Further, there is a need for easy to operate apparatuswhere users can shred failed prints into granules and feed them back into the system, promotinga circular economy approach in 3D printing. It would be desirable to provide a system andmethod that addresses this gap by introducing a table-top filament extrusion system that enablesusers to fabricate FFF filament using virgin or recycled thermoplastic granules and is easy touse, portable, has aesthetic appeal, compact with entire setup housed within a single compactmainframe, fully operable by a single user and requires no specialized training or externalintervention, making such system ideal for makerspaces, research labs, educational institutions,and hobbyists alike. The present invention meets at least one of the above and other needs.SUMMARY OF THE INVENTION

[004] In accordance to a first embodiment of present invention, a filament extrusion systemcomprising: an extrusion unit, a diameter sensing unit, a puller unit, a spooling unit, and a mainframe for housing the extrusion unit. The extrusion unit comprises a vertically oriented screwextruder configured to melt and convey thermoplastic material; a hopper mounted above thescrew extruder, having a funnel geometry and internal baffles to facilitate mixing and flow,configured to feed thermoplastic material; a motor coupled to the screw and a double coaxialthrust bearing assembly, arranged in between the screw and motor, to transmit torque whilemaintaining axial alignment; a barrel enclosing the screw, the barrel comprising multipleheating zones with external heaters configured to melt the polymer and a pineapple-cut mixingsection at the extrusion end of the screw; a nozzle mounted at the end of the barrel for extrudingthe melted thermoplastic into a filament of diameter based on nozzle opening size; and acooling zone configured to solidify the extruded filament. The diameter sensing unit positioneddownstream of the nozzle is configured to measure the extruded filament diameter. The pullerunit positioned downstream of the diameter sensing unit, is controlled by a closed-loopfeedback mechanism based on diameter measurements, to maintain the filament diameter aspredefined by a user. The spooling unit is configured to collect the filament.

[005] In one embodiment, the screw extruder comprises a single-flight, high-pitch screwconfigured to mechanically convey the material forward at low rotational speeds in the rangeof 3-16 RPM and to deliver at least 1 kg / hr extrusion rate.

[006] In one other embodiment, said hopper is constructed from laser-cut and welded metalsheets, preferably stainless steel and includes a spill-proof cover with a trapezoidal slot for safeuser access and refilling and the hopper has a funnel geometry.

[007] In another embodiment, the motor is coupled to the screw via an Oldham's coupling.

[008] In yet another embodiment, the pineapple mixing section of the screw comprisesalternating clockwise and counter-clockwise helical grooves to facilitate multi-materialblending and homogenization.

[009] In a further embodiment, the double thrust bearing assembly comprises coaxiallyaligned, oppositely facing NKX-15 needle-roller combination bearings to handle axial loadsinduced by extrusion pressure and screw weight.

[0010] In yet other embodiment, the nozzle may be made up of materials selected from a groupconsisting of brass (such as gun metal), nitrided steel (such as EN41B), stainless steel and toolsteel, and the filament exiting the nozzle is subjected to forced convection air cooling in thecooling zone.

[0011] In yet other embodiment, the filament diameter sensing unit is a Hall-effect or opticalsensor configured to operate in a closed-loop control with the puller speed to achieve a filamentdiameter between 1.7 mm and 1.8 mm and measures the extruded filament diameter in realtime.

[0012] In a further embodiment, the spooling unit comprises a dynamically variable speedmechanism to maintain constant filament linear velocity and is designed to dynamically adjustrotational speed based on real-time calculation of spool diameter and filament feed rate tomaintain constant linear velocity ensuring even winding.

[0013] In a further embodiment, the filament is redirected tangential to the diameter of spoolvia a positioner arm to align with the spooling axis, increasing residual stresses and improvingfilament quality. The positioner arm moves back and forth across the set width of the spoolwith a calculated speed with respect to the speed of spooling for said alignment.

[0014] In a further embodiment, said system further comprises a processor unit connected tothe heating zones, diameter sensing unit, puller unit, and spooling unit, the processorconfigured to calculate filament dimensional accuracy based on real-time sensor input, andwherein the processor executes control algorithms including PID control for heater zones,diameter regulation, and motor speed adjustments.

[0015] In yet another embodiment, the diameter sensing unit measures the filament diameterin real-time and sends the data to the processor, the processor compares the measured valuewith the value of the filament diameter predefined by a user and calculates the differencebetween the predefined value and the measured value.

[0016] In another embodiment, the processor is configured to reduce the speed of the puller toallow more material to accumulate when the measured diameter is smaller than the predefinedvalue and / or the processor is configured to increase the speed of the pullers to stretch thefilament and reduce the diameter of the filament when the diameter is larger than the predefinedvalue.

[0017] In yet another embodiment, said system further comprises a cooling unit with forcedair fans directed at the hopper to prevent premature softening of the feedstock by maintainingthe temperature below the material's glass transition temperature.

[0018] In yet another embodiment, the system is modular and comprises detachable extruderand spooler units, allowing for extended filament cooling paths or independent operation.

[0019] In still another embodiment, the system is powered by a switched-mode power supplyand includes emergency stop buttons and safety relays to cut off power in case of overheating,motor stalling, or sensor failure.

[0020] In another embodiment, the present invention provides a method for producingfilaments using filament extrusion system, comprising: feeding virgin or recycledthermoplastic material into an extrusion unit comprising a funnel geometry hopper and internalbaffles to facilitate mixing and flow; conveying and melting the thermoplastic material using avertically aligned single-screw extruder mounted below the hopper with pineapple-cut mixinggeometry; transmitting torque while maintaining axial alignment between a motor coupled tothe screw and a double coaxial thrust bearing assembly, arranged in between the screw andmotor; applying controlled heating through multiple heating zones including multiple externalheaters mounted on the barrel, enclosing the screw, to melt the thermoplastic material andmixing the melted material in a pineapple-cut mixing section at the extrusion end of the screw;extruding the molten material through a nozzle mounted at the end of the barrel to form afilament of diameter based on nozzle opening size; cooling the extruded filament in a coolingzone to solidify the extruded filament; measuring the diameter of the extruded filament usinga diameter sensing unit positioned downstream of the nozzle; adjusting the speed of pullerrollers of a puller unit based on a closed-loop feedback mechanism, based on the measuredfilament diameter to maintain dimensional accuracy as predefined by a user; collecting thefilament on a spooling unit.

[0021] In one embodiment, the method further comprises calculating optimal extrusionparameters including screw pitch, extrusion pressure, and motor torque using analytical modelsfor flow rate, viscosity, and material properties.

[0022] In one other embodiment, the polymer feedstock melts progressively along the barrelwith combination of mechanical shear and thermal energy.

[0023] In one embodiment, the hopper is constructed from laser-cut and welded metal sheets,preferably stainless steel, and includes a spill-proof cover with a trapezoidal slot for safe useraccess and refilling, and the hopper has a funnel geometry.

[0024] In another embodiment, the screw extruder comprises a single-flight, high-pitch screwconfigured to mechanically convey the material forward at low rotational speeds in the rangeof 3-16 RPM and to deliver at least 1 kg / hr extrusion rate.

[0025] In yet another embodiment, the pineapple mixing section of the screw comprisesalternating clockwise and counter-clockwise helical grooves to facilitate multi-materialblending and homogenization.

[0026] In one embodiment, the double thrust bearing assembly comprises coaxially aligned,oppositely facing NKX-15 needle-roller combination bearings to handle axial loads inducedby extrusion pressure and screw weight.

[0027] In one other embodiment, the nozzle may be made up of materials selected from a groupconsisting of brass, nitrided steel, stainless steel, and tool steel, and the filament exiting thenozzle is subjected to forced convection air cooling in the cooling zone.

[0028] In another embodiment, the filament diameter sensing unit is a Hall-effect or opticalsensor configured to operate in a closed-loop control with the puller speed to achieve a filamentdiameter between 1.7 mm and 1.8 mm and measures the extruded filament diameter in realtime.

[0029] In one embodiment, the spooling unit comprises a dynamically variable speedmechanism to maintain constant filament linear velocity that dynamically adjusts rotationalspeed based on real-time calculation of spool diameter and filament feed rate to maintainconstant linear velocity ensuring even winding.

[0030] In yet another embodiment, the filament is redirected tangential to the diameter of spoolvia a positioner arm to align with the spooling axis, increasing residual stresses and improvingfilament quality, and wherein the positioner arm moves back and forth across the set width ofthe spool with a calculated speed with respect to the speed of spooling for said alignment.

[0031] In one other embodiment, the method further comprises a processor unit connected tothe heating zones, diameter sensing unit, puller unit, and spooling unit, wherein the processoris configured to calculate filament dimensional accuracy based on real-time sensor input, andwherein the processor executes control algorithms including PID control for heater zones,diameter regulation, and motor speed adjustments.

[0032] In another embodiment, the diameter sensing unit measures the filament diameter inreal-time and sends the data to the processor, the processor compares the measured value withthe value of the filament diameter predefined by a user and calculates the difference betweenthe predefined value and the measured value.

[0033] In one embodiment, the processor is configured to reduce the speed of the puller toallow more material to accumulate when the measured diameter is smaller than the predefinedvalue and / or the processor is configured to increase the speed of the pullers to stretch thefilament and reduce the diameter of the filament when the diameter is larger than the predefinedvalue.

[0034] In yet another embodiment, the method further comprises a cooling unit with forced airfans directed at the hopper to prevent premature softening of the feedstock by maintaining thetemperature below the material's glass transition temperature.

[0035] In one other embodiment, the system is powered by a switched-mode power supply andincludes emergency stop buttons and safety relays to cut off power in case of overheating,motor stalling, or sensor failure.BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0036] Figure 1 shows the block diagram of the filament extrusion system of the presentinvention, in accordance with the embodiments of the present invention.

[0037] Figure 2 shows schematic diagram of the filament extrusion system: 2a perspectiveview of the filament extrusion system of the present invention, 2b front view of the filamentextrusion system of the present invention, 2c side view of the filament extrusion system of thepresent invention, 2d isometric view of the filament extrusion system of the present invention,in accordance with the embodiments of the present invention.

[0038] Figure 3 shows schematic diagram of screw extruder: 3a perspective view of the screwextruder, 3b exploded view of the screw extruder, 3c side view of the screw extruder, inaccordance with the embodiments of the present invention.

[0039] Figure 4 shows schematic diagram of barrel: 4a cross-sectional view of outer surfaceof barrel, 4b cross-sectional view of inner surface of barrel, 4c perspective view of barrel, inaccordance with the embodiments of the present invention.

[0040] Figure 5 shows schematic diagram of nozzle: 5a front view of the nozzle, 5b crosssectional view of the nozzle, 5c top view of the nozzle, 5d perspective view of the nozzle, inaccordance with the embodiments of the present invention.

[0041] Figure 6 shows schematic diagram of spooling unit: 6a side view of the spooling unit,6b front view of the spooling unit, 6c back view of the spooling unit, 6d exploded view of thespooling unit, in accordance with the embodiments of the present invention.

[0042] Figure 7 shows schematic diagram of single screw extrusion: 7a Geometrical featuresof the extruder screw, 7b Graphical representation of flow through the nozzle of the presentinvention, in accordance with the embodiments of the present invention.

[0043] Figure 8 shows schematic diagram of the closed-loop feedback mechanism, inaccordance with the embodiments of the present invention.

[0044] Figure 9 shows structural analysis on the extruder screw: 9a meshed profile, 9b stressdistribution (deformation scale:7.6), 9c displacement plot (deformation scale:1), in accordancewith the embodiments of the present invention.

[0045] Figure 10 shows Structural analysis on the frame: 10a meshed profile, 10b stressdistribution (deformation scale:194), 10c displacement plot (deformation scale:1), inaccordance with the embodiments of the present invention.

[0046] Figure 11 shows Thermal simulation results: 11a barrel and nozzle regions at extrusiontemperature (450 oC), 11b throat area near the hopper, maintained at forced cooling, 11ccoupler region, maintained at forced cooling, 11d generated mesh profile, 11e temperaturedistribution in the assembly at time step: 6 (3600 s / 1 hr) , in accordance with the embodimentsof the present invention.

[0047] Figure 12 shows the schematic flowchart of the method of the present invention, inaccordance with the embodiments of the present invention.

[0048] Figure 13 shows the schematic flowchart of the method of the present invention, inaccordance with the embodiments of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention discloses a filament extrusion system and a method for producingfilaments for maintaining dimensional accuracy and quality of extruded filaments.

[0050] An embodiment of the present invention includes a filament extrusion systemcomprising: an extrusion unit, a diameter sensing unit, a puller unit, a spooling unit, and a mainframe for housing the extrusion unit. The extrusion unit may comprise a vertically orientedscrew extruder which may further be configured to melt and convey thermoplastic material; ahopper mounted above the screw extruder, having a funnel geometry and internal baffles tofacilitate mixing and flow, configured to feed thermoplastic material; a motor coupled to thescrew and a double coaxial thrust bearing assembly, arranged in between the screw and motor,to transmit torque while maintaining axial alignment; a barrel enclosing the screw, the barrelcomprising multiple heating zones with external heaters configured to melt the polymer and apineapple-cut mixing section at the extrusion end of the screw; a nozzle mounted at the end ofthe barrel for extruding the melted thermoplastic into a filament of diameter based on nozzleopening size; and a cooling zone configured to solidify the extruded filament. The diametersensing unit positioned downstream of the nozzle is configured to measure the extrudedfilament diameter. The puller unit positioned downstream of the diameter sensing unit, iscontrolled by a closed-loop feedback mechanism based on diameter measurements, to maintainthe filament diameter as predefined by a user. The spooling unit is configured to collect thefilament.

[0051] Hereinafter, the present invention will be described in detail with reference to thedrawings. Note that, the present invention is not limited by embodiments and examples. Inaddition, components in the embodiments and the examples include those that may be easilyassumed by those skilled in the art or are practically the same.

[0052] In some exemplary embodiments of the present invention, FIG. 1 is a block diagram ofthe filament extrusion system (100) according to one embodiment of the present invention. Asdepicted, the system (100) includes a main frame (102) that may support all components andensures proper alignment. A motor / drive motor (104) may be mounted on the frame (102) andmay provide rotational power to the screw (110) through a coupling and bearing arrangement.A hopper (106) may be positioned above the screw (110) to receive thermoplastic feedstock,such as, but not limited to, pellets or recycled granules, and direct them into the extrusion barrel(108). The screw (110) may convey and compress the material inside the barrel (108), whileone or more heating zones (112) may melt the material as it advances toward the extrusion end.The molten material may be extruded through a nozzle (114), which shapes the material into acontinuous filament. The filament may then pass through a cooling zone (116) where it issolidified to maintain its shape. Downstream of the cooling zone, a diameter sensing system(118) may measure the filament thickness in real time and may send feedback to the puller unit(120). Based on the feedback, the puller unit (120) may adjust its speed to maintain a consistentfilament diameter. Finally, the spooling unit (122) may collect the filament onto a spool forstorage and later use.

[0053] In some exemplary embodiments of the present invention, FIG. 2 is a schematicdiagram of the filament extrusion system according to one embodiment of the presentinvention. FIG. 2A illustrates a perspective view of the filament extrusion system, showing thecompact vertical arrangement of the main frame (102), wherein the main frame (102) mayhouse at least one of, the motor (104), hopper (106), screw (110), barrel (108), heating zone(112), and the downstream components including, but not limited to, the nozzle ((114), coolingzone (116), diameter sensing system (118), puller unit (120) and spooling unit (122). FIG. 2Band FIG. 2C illustrates a front view and side view of the system, highlighting the coaxialarrangement of the motor (104), coupling (124), thrust bearings (126), and the screw (110)inside the barrel (108). The heating zones (112) are mounted externally on the barrel (108), andthe nozzle (114) is aligned along the same axis for extrusion of the filament. The diametersensing system (118) is shown positioned below the nozzle (114), followed by the puller unit(120) and the spooling unit (122). FIG. 2D illustrates an isometric view of the filamentextrusion system, showing the internal structural arrangement and mounting of componentswithin the main frame (102).

[0054] In one of the exemplary embodiments of the present invention, the filament extrusionsystem may be a table-top setup which may use a uniquely developed single screw extrudersetup, driven by a high torque, low speed stepper motor / drive motor (104) and equipped witha diameter sensing unit (118) and spooling unit (122), to directly fabricate an end user product.The entire system may be housed in a light-weight sheet metal casing which may provide thenecessary strength, mounting, thermal and mechanical safeguard, and a bounding volume tothe system.

[0055] In one of the exemplary embodiments of the present invention, the stepper motor (104)may be used to precisely control the rotation of components such as, but not limited to, thescrew (110) for pushing melted plastic or the pullers for drawing filament. Their ability to movein discrete steps makes them ideal for accurate extrusion.

[0056] In one exemplary embodiment of the present invention, the main frame (102) of themachine may be made using sheets / composite polymers to get the required strength withminimal weight, which may help with the rust resistance and paint coats. The sheets may bepreferably made using metal or composite polymers, preferably powder coated mild steel (MS),stainless steel or the like. The main frame (102) may be provided with extrusion rods forstructural integrity which are fixed with the laser cut sheet parts using pre-designed slots.

[0057] In one exemplary embodiment of the present invention, the entire main frame (102)may be configured to fit within dimensions of approximately 500 mm x 500 mm, with theoverall height maintained at a minimal level to ensure compactness and stability of thestructure,, which may weigh between 22 kg and 40 kg, preferably about 30 kg, excluding thespooling unit (122), which is 350±100 mm x 300±100 mm x 400±100 mm. The main drivemotor (104) may be a NEMA 34 motor, however, other higher-torque NEMA series motors orequivalent motors from different manufacturers may also be employed, depending on thedesired performance requirements. For example, the main drive motor (104) may be NEMA34 of 85 mm x 85 mm x 112 mm with a drive shaft of 12.7 mm diameter and 30 mm length.The drive motor (104) may be clamped to an Oldham coupling (124).

[0058] In some exemplary embodiments of the present invention, NEMA 34 may be used.NEMA stands for National Electrical Manufacturers Association. More particularly, the termNEMA 34 refers to a standardized frame size for stepper motors, meaning the motor'sdimensions (85mm x 85mm) are designed to fit the NEMA 34 specification.

[0059] In one exemplary embodiment of the present invention, a mixing baffle may be presentinside the hopper (106) which may be made using metal or composite polymers, preferablystainless steel (SS). The screw (110) and barrel (108) may be made of plastic friendly nitrideEN41b nitriding steel. The screw (110), barrel (108) and nozzle (114) are axis-symmetricelements and hence, may be produced on a lathe machine, followed by proper heat and surfacetreatment.

[0060] In one exemplary embodiment of the present invention, the screw extruder comprises asingle-flight, high-pitch screw (110) configured to mechanically convey the material forwardat low rotational speeds in the range of 3-16 RPM and to deliver at least 1 kg / hr extrusion rate.

[0061] In one exemplary embodiment of the present invention, the hopper (106) may beconstructed from laser-cut and welded metal sheets, providing an ease of manufacturing. Thehopper assembly is made using metal sheets which are bended and then welded together. Themetal may be preferably selected from stainless steel, aluminium, brass or the like. The bottompart of the hopper (106) that has to mate with the barrel (108), may be custom machined on a3-axis CNC mill. The hopper (106) may include a spill-proof cover with a trapezoidal slot forsafe user access and refilling. The hopper (106) may have a funnel geometry, preferably squareshaped.

[0062] In one of the exemplary embodiments of the present invention, the entire assembly maybe designed to press-fit and fasten together with ease. In addition, the assembly may bedesigned to be easy in case the screw (110) needs to be removed for cleaning.

[0063] In another embodiment, the motor (104) may be coupled to the screw (110) via anOldham's coupling (124). In general, the Oldham coupling is a type of mechanical couplingused to connect two parallel shafts that are slightly misaligned. The Oldham's coupling (124)may be made from a combination of brass centre and SS flanges. The Oldham's coupling (124),placed between the screw (110) and the drive motor (124), takes care of any radial distortions,further improving the accuracy and precision of the machine.

[0064] In some exemplary embodiments of the present invention, the Oldham coupling (124)may be of diameter 30±5 mm and a combined length (all 3 sections) of 33±5 mm. The otherend of the coupling may be joined with the screw (110). Both the joints may be secured usingkeyways.

[0065] In yet another exemplary embodiment of the present invention, the pineapple meshsection (128) of the screw (110) may comprise alternating clockwise and counter-clockwisehelical grooves to facilitate multi-material blending and homogenization.

[0066] In a further exemplary embodiment of the present invention, the double thrust bearingassembly comprises coaxially aligned, oppositely facing NKX-15 needle-roller combinationbearings to handle axial loads induced by extrusion pressure and screw weight.

[0067] In yet other exemplary embodiment of the present invention, the nozzle (114) may bemade up of materials selected from a group consisting of brass (such as gun metal), nitridedsteel (such as EN41B), stainless steel and tool steel, or other equivalent high-strength alloyscapable to withstand high temperatures and shearing forces.

[0068] In yet another exemplary embodiment, the nozzle (114) may be a precision-machinedbrass or EN41b nozzle and the filament exiting the nozzle (114) is subjected to forcedconvection air cooling in the cooling zone.

[0069] In yet other exemplary embodiment of the present invention, the filament diametersensing unit (118) may be a Hall-effect or optical sensor configured to operate in a closed-loopcontrol with the puller speed to achieve a filament diameter between 1.72 mm and 1.78 mmand may measure the extruded filament diameter in real time. In one preferable embodiment,the filament diameter achieved may be between 1.72 mm and 1.78mm.

[0070] In a further exemplary embodiment of the present invention, the spooling unit (122)may further comprise a dynamically variable speed mechanism to maintain constant filamentlinear velocity and may be designed to dynamically adjust rotational speed based on real-timecalculation of spool diameter and filament feed rate to maintain constant linear velocityensuring even winding.

[0071] In some exemplary embodiments of the present invention, the system may furthercomprise a control unit (101), which may include one or more processing elements configuredto perform computational and control operations necessary for system functionality. Thecontrol unit (101) may be responsible for overseeing and coordinating various systemcomponents, and it may interface with a processing unit designed to execute computationallyintensive tasks. The control unit (101) may include, but is not limited to, one or moremicroprocessors, microcontrollers, digital signal processors (DSPs), application-specificintegrated circuits (ASICs), field-programmable gate arrays (FPGAs), or any combinationthereof. It may be operatively coupled to memory components that store executableinstructions, system parameters, or operational data.

[0072] In a further exemplary embodiment of the present invention, the processing unit maybe connected to the heating zones (112), diameter sensing unit (118), puller unit (120), andspooling unit (122). This processing unit may be configured to calculate filament dimensionalaccuracy based on real-time sensor (103) inputs, thereby ensuring that the filament productionprocess is highly controlled and precise. The processing unit may be a high-performance CPU,GPU, or TPU, with AI acceleration capabilities, designed to execute control algorithms andissue commands in real-time or near-real-time. The control unit, in turn, may support wired orwireless communication with other system components or external devices, facilitating smoothoperation and integration.

[0073] In a further exemplary embodiment of the present invention, the heating zones (112) ofsaid system consist of heaters and temperature sensors such as but not limited to, thermocouplesor thermistors, used to melt the thermoplastic material. Proper control of these heaters mayensure uniform melting and flow of the polymer through the nozzle. Sensors (103) may includetemperature sensors for heating control and diameter sensors like laser micrometres or opticalsensors, etc, to monitor filament thickness. These sensors (103) may provide real-time feedbackessential for process stability.

[0074] In another exemplary embodiment of the present invention, the processor may beArduino-based herein referred to as Arduino microcontroller and may execute controlalgorithms including but not limited to, PID control for heating zones (112), diameterregulation, and motor speed adjustments. The Arduino microcontroller may serve as the brainof the system and reads sensor data, runs control algorithms (like PID), and sends commandsto drivers and heaters, ensuring coordinated system behavior.

[0075] In some exemplary embodiments of the present invention, the system may also includedrivers. The drivers may act as intermediaries between the microcontroller and componentslike stepper motors. The drivers may amplify control signals to deliver the appropriate currentand voltage, enabling smooth and reliable operation of motors.

[0076] In yet another exemplary embodiment of the present invention, the diameter sensingunit (118) may measure the filament diameter in real-time and send the data to the processor,the processor may further compare the measured value with the value of the filament diameterpredefined by a user and calculates the difference between the predefined value and themeasured value.

[0077] In another exemplary embodiment of the present invention, the processor may also beconfigured to reduce the speed of the puller to allow more material to accumulate when themeasured diameter is smaller than the predefined value and / or the processor is configured toincrease the speed of the pullers to stretch the filament and reduce the diameter of the filamentwhen the diameter is larger than the predefined value.

[0078] In yet another exemplary embodiment of the present invention, the cooling unit / coolingzone (116) may further comprise forced air fans directed at the hopper to prevent prematuresoftening of the feedstock by maintaining the temperature below the material's glass transitiontemperature .

[0079] In yet another exemplary embodiment of the present invention, the system may bemodular and may comprise detachable extruder and spooler units (122), allowing for extendedfilament cooling paths or independent operation.

[0080] In one exemplary embodiment of the present invention, the system may be powered bya switched-mode power supply and may further include emergency stop buttons and safetyrelays to cut off power in case of overheating, motor stalling, or sensor failure. The SwitchedMode Power Supply (SMPS) provides regulated power to the entire extrusion setup andefficiently converts AC mains power to the required DC voltage levels for example, 12V or24V, needed to run heaters, motors, and electronics. Emergency Stop and Safety Relays,included for safety, provide manual or automatic emergency stop mechanism to cut power incase of overheating, motor stalls, or other failures.

[0081] In an exemplary embodiment of the present invention, Fig. 3 depicts schematic diagramfor the screw extruder according to one embodiment of the present invention. FIG. 3A and FIG.3C illustrates a perspective and side view of the screw respectively having a helical geometry.The screw includes a compression zone with a gradually increasing root diameter forprogressive material densification, and a pineapple-cut mixing section at the extrusion end toimprove melt homogeneity. FIG. 3B illustrates an exploded view of the screw, highlighting theflight dimensions and core geometry.

[0082] In an exemplary embodiment of the present invention, the screw (110) may have a totallength of about 340±100 mm with an outer diameter of about 25 mm. The extrusion sectionmay be about 208±100 mm starting with a straight section of 20 mm with a root diameter of15 mm, which then gradually enlarges to 21 mm root diameter over 75 mm length. The sameroot diameter may be kept in the final compression zone before mixing for 50 mm. Theminimum flight width may be 4 mm. The pineapple cut section (128) at the end may be of 53.2mm length with 40.8 mm mixing zone and the rest is tapered to a point. The pineapple zone(128) may have 10 or more threads (5 or more clockwise and 5 or more anti-clockwise) with a2 mm deep triangular cut (45o).

[0083] In an exemplary embodiment of the present invention, two thrust bearings preferablyNKX-15 thrust bearings (126) may be mounted coaxially and counter parallel between thescrew and the coupling to take care of the axial deviations. The bearing (126) may be acombination of needle and roller bearings, integrating radial and axial load handling. The borediameter may be 15 mm, outer diameter may be about 29 mm and the width may be about 23mm. The bearings may be mounted on the screw (110) where they may be maintained at 15mm diameter for a 60 mm length. A collar may be added in between the bearing to provide acommon face for mounting. The collar may have 15 mm ID (Inside Diameter), 30 mm OD(Outside Diameter) and 7 mm thickness, with a through M3 hole passing through the diameterat the center of the collar, orthogonal to the cylinder's axis. The two bearings and the collarmay be housed in a metal covering with 50mm OD, 31 mm length and 3.5 mm wall thickness.This assembly is secured with the mainframe (102) using two cylindrical holders, which holdthe bearings assembly, and are screwed to the frame (102). The top holder may have a 70 mmOD with 5 mm thickness which is pressed with a sheet metal frame. This surface may have 4through 6.5 mm holes at 60 mm PCD. The next step may be of about 48 mm diameter with 5mm thickness. The final step may be of about 41 mm diameter, 3 mm thickness and may have4 through holes of 3.3 diameter arranged at 35 mm PCD, 90o with the first set of holes. Thebottom holder may have an OD of 48.3 mm up to 10 mm followed by a step of 40.8 mm of 3mm thickness. The step may have 4 through holes of 3.3 mm diameter at 35 mm PCD. Boththe holders may have a central through hole of 24.5 mm for the screw (110).

[0084] In another exemplary embodiment of the present invention, before the barrel (108), thehopper assembly may be mounted which acts as the material sump. The hopper (106) designmay be a square, conical, or circular shaped funnel and may be made using 1 mm sheet metal,starting with 210±10 mm x 210±10 mm size towards the motor end, converging to 60 mm x60 mm towards the barrel end. The convergence occurs over a normal length of 80 mm,followed by a prismatic section of 19 mm. The opening size of the funnel is dependent on thelength and width of the extruder unit. The hopper (106) has a cover on the top to prevent overspilling of the pelletized feedstock. The cover may be made using 1 mm sheet metal with acentral hole of 50 mm for the screw (110) to pass through and a trapezoidal slot (44 mm deepwith 185 mm opening converging to 95 mm) on the front. The slot or hole is for easy accessand is in the plane of the cover.

[0085] In another exemplary embodiment of the present invention, Fig. 4 depicts the schematicdiagram of barrel (108) according to one embodiment of the present invention. FIG. 4Aillustrates a cross-sectional view of the outer surface of the barrel (108). The barrel (108) isgenerally cylindrical and configured to house the screw (110), with sufficient wall thickness towithstand the internal pressure generated during extrusion. FIG. 4B illustrates a cross-sectionalview of the inner surface of the barrel (108), showing the internal bore through which the screw(110) rotates. The end section of the barrel is provided with internal threading (130) formounting the nozzle (114) securely. FIG. 4C illustrates a perspective view of the barrel (108),highlighting its cylindrical shape and threaded end (130) for nozzle (114) attachment. Thebarrel (108) is designed to accommodate external heating elements along its length forcontrolled melting of the thermoplastic material.

[0086] In an exemplary embodiment of the present invention, the screw (110) may be coaxially housed inside a barrel (108) of 25 mm ID, 40 mm OD and 200 mm length. The 17 mmfrom the nozzle (114) side may be internally threaded (130) between 30-35 mm. The hoppedside may be stepped at 35 mm OD for 15 mm length with a chamfered opening at 60oforconnectivity with the hopper (106) and better material (pellet) flow. The 100 mm outer surfaceof the barrel (108), towards the nozzle (114) side may be used for mounting of the externalheaters (50 mm in length).

[0087] In another exemplary embodiment of the present invention, the hopper (106) may beconnected to the barrel (108) by a barrel flange. The barrel flange may be a cylindrical elementwith 90 mm OD and 15 mm thickness. The hopper (106) side may have a 60 mm x 60 mmsquare hole machined to 5 mm. Four M6 through holes may be tapped at a PCD of 75 mm. Thedesign mat also feature a 35 mm through hole at the centre for the screw (110).

[0088] In some exemplary embodiments of the present invention, at the end of the barrel (108),the nozzle may be threaded (130) to give the final shape to the polymer extrusion. FIG. 5depicts a schematic diagram of the nozzle (114) as an integral component of the filamentextrusion system.

[0089] In some exemplary embodiments of the present invention, FIG. 5A illustrates the frontview of the nozzle (114), showing the overall geometric outline, including the threaded section(130), gripping surfaces, and the converging extrusion tip that characterizes the nozzle profile.

[0090] In some exemplary embodiments of the present invention, FIG. 5B presents the crosssectional view of the nozzle (114), offering detailed insight into the internal structure. Thisfigure depicts the converging internal taper that guides the molten filament toward the preciseopening at the nozzle tip, as well as the threading (130) used for attachment within the extruderassembly.

[0091] In some exemplary embodiments of the present invention, FIG. 5C depicts the top viewof the nozzle (114), providing clarity on the arrangement and central positioning of theextrusion opening, relative to the hexagonal external profile designed for enhancedcompatibility during installation or removal.In some exemplary embodiments of the present invention, FIG. 5D shows the perspective viewof the nozzle (114), effectively combining spatial aspects of both the front and side profiles,thereby providing an integrated visual understanding of the nozzle's overall geometry asillustrated in the present invention.In another exemplary embodiment of the present invention, the internal geometry of the nozzle(114) may start with a 25 mm diameter opening, which may converge to 3 mm diameter overa normal distance of 37 mm, and may be held constant for 10 mm. The nozzle face at theopening may be of 7 mm OD followed by a 15 mm long hexagonal section with a minimumwidth of 32 mm, for each clamping and mounting. The design may feature 15 mm externalthread length while the entire length and bounding diameter of the nozzle may be 47 mm and40 mm, respectively.

[0092] In some exemplary embodiments of the present invention, FIG. 6 depicts the schematicdiagrams of the spooling unit (122), illustrating various views and the exploded assembly ofthe components in relation to the present invention.

[0093] In some exemplary embodiments of the present invention, FIG. 6A illustrates the sideview of the spooling unit (122). This view may capture the orthogonal spooling mechanism inwhich the extruded filament may be guided by a positioner arm (134). The positioner arm (134)may bend the filament tangentially to the diameter of the spool, ensuring that the filament exitsin alignment with the spooling shaft (132). This controlled movement may preserve filamentquality by minimizing strain and brittleness. The puller unit (122) may be positioned beforethe positioner arm (134) and functions to grip and control the drawing speed of the filament,ensuring consistent tension and extrusion during spooling.

[0094] In some exemplary embodiments of the present invention, the term "orthogonalspooling mechanism" is employed in the filament extrusion and spooling process. The extrudedfilament is directed through a positioner arm (134) that bends the filament tangentially relativeto the diameter of the spool, aligning the filament with the spooling shaft (132). This alignmentminimizes elastic strain on the filament, which contributes to an improvement in its fatigue lifeand reduces brittleness. Furthermore, the positioner arm (134) is designed to move back andforth across the set width of the spool at a calculated speed, synchronized with the speed of thespooling process. This ensures optimal alignment of the filament during spooling, minimizingstress and improving the overall quality of the final filament product.

[0095] In some exemplary embodiments of the present invention, FIG. 6B presents the frontview of the spooling unit (122). The forefront perspective provides a clear visualization of thepositioner arm's range of motion as it traverses the width of the spool, accurately aligning thefilament to lay down evenly during the winding process. The puller unit (122), may work incoordination with the positioner arm (134) to regulate filament feed rate and maintain uniformtension.

[0096] In some exemplary embodiments of the present invention, FIG. 6C depicts the backview of the spooling unit (122), highlighting structural features such as ventilation and accesspanels. This view may also reveal the mounting positions of the drive motors (142).

[0097] In some exemplary embodiments of the present invention, FIG. 6D shows the explodedview of the back side of the spooling unit (122). This detailed illustration breaks down theassembly including the enclosure, spool shaft (132), clutch mechanism (140), positioner arm(134), and control unit integrated with the puller unit (136). The exploded perspective clarifieshow component interactions are designed to facilitate smooth, automated, and reliable filamentspooling in the system.

[0098] In some exemplary embodiments of the present invention, the spooling unit (122) isdesigned to collect and wind the extruded filament onto a spool in a uniform and consistentmanner. The unit (122) ensures proper filament lay without introducing mechanical stress ordeformation in the filament, even under conditions of fluctuating extrusion rates. The spoolingunit (122) primarily comprises a motor-driven spool holder, a positioner arm (134) for guidingthe filament, and a manually adjustable clutch mechanism (140) that provides controlledslippage during winding.

[0099] In some exemplary embodiments of the present invention, the positioner arm, consistsof a screw and nut mechanism (138) attached to a cantilever-type extension. The primaryfunction of this positioner arm (134) is to translate forward and backward along a defined axis,thereby guiding the filament evenly across the spool width during winding. This movementallows the filament to be layered systematically without overlapping or creating bunching.

[00100] In some exemplary embodiments of the present invention, the translationdistance of the positioner is determined based on the specified width of the spool, which mayvary depending on user preference or application requirements. The control unit (136) maycalculate the total stroke length required for the positioner arm (134) and sets the motionaccordingly. The stroke length refers to the total linear distance the positioner travels back andforth across the spool width to guide the filament uniformly during the winding process. Thetranslation speed of the positioner arm (134) may be synchronized with the rotational speed ofthe spool so that the filament lays down in a helical pattern along the spool's surface. As thefilament builds up on the spool, the diameter may increase incrementally, typically by twicethe filament diameter per layer, and the positioner arm (134) may adjusted to maintainconsistent spacing and alignment of subsequent windings.

[00101] In some exemplary embodiments of the present invention, the spool mountingmechanism may consist of a threaded shaft (132) extending horizontally from the centre of theenclosure. This shaft (132) may be configured to receive a filament spool with a central bore.The spool may be inserted onto the shaft (132) and secured in place by a wing-nut-type clamp,which threads onto the rod from the outer side. This may ensure that the spool is held firmly inplace during operation.

[00102] In some exemplary embodiments of the present invention, the rotation of thespool may be facilitated by a motor-clutch-drive (140) assembly positioned at the rear of thespooling unit (122). The motor, mounted on the upper side of the housing, is connected to themain spool shaft via a belt-driven gear system (144). The gear reduction ratio may be set to3:1, meaning that for every three revolutions of the motor (142), the spool shaft (132) rotatesonce. This arrangement provides the necessary torque while maintaining smooth motion.

[00103] In some exemplary embodiments of the present invention, one or more criticalfeature of the system may be the clutch mechanism (140), which may be integrated betweenthe gear assembly (144) and the spool shaft (132). The purpose of the clutch (140) may be tointroduce a controlled amount of slippage between the drive motor (142) and the rotating spool.This slip may compensate for minor inconsistencies in filament extrusion, such as, but notlimited to, fluctuations in diameter or momentary pauses. The clutch tension may be adjustedvia a spring-loaded knob located at the free end of the shaft (132). By tightening or looseningthe knob, the operator may increase or decrease the resistance applied to the shaft (132),effectively regulating the degree of slippage.

[00104] In some exemplary embodiments of the present invention, the above featuremay particularly be important because excessive tension in the spooling system (122) mayresult in filament being stretched, leading to dimensional inaccuracies or mechanicalweakening. Conversely, insufficient tension may lead to slack in the filament, causing unevenwinding or tangling. Thus, the manual clutch adjustment may allow users to fine-tune thesystem based on the material properties such as, but not limited to, viscosity, elasticity andextrusion rate of the filament.

[00105] In some exemplary embodiments of the present invention, during operation, thefilament may flow into the spooling unit (122) from the diameter sensing system (118). Therotation of the spool and the translation of the positioner arm (134) may be synchronized viathe controller (136) to ensure that the filament is wound in successive layers with minimaloverlap and consistent tension. As the effective diameter of the wound spool increases, thesystem may dynamically adjust winding parameters to maintain consistent linear spoolingspeed.

[00106] In some exemplary embodiments of the present invention, the modular designof the spooling unit (122) may allow for easy maintenance, replacement of components, andadaptability for spools of various sizes. The user-accessible design, combined with automatedcontrol and manual overrides for example, clutch tension knob, provides both precision andflexibility, making the system suitable for continuous and high-fidelity filament winding inFFF applications.

[00107] In some exemplary embodiments of the present invention, FIG. 7 depictsschematic diagrams of a single screw extrusion system, including 7A, illustrating thegeometrical features of the extruder screw (110) and 7B, illustrating a graphical representationof the material flow through the nozzle (114).

[00108] In some exemplary embodiments of the present invention, Figure 7(a) illustratesthe geometrical features of the extruder screw (110). The screw (110) may comprise a helicalflight with a defined pitch (p), channel depth (h), and channel width (w). The helix angle (δ)governs the direction of material conveyance. The unwrapped channel view may highlight theeffective channel length (Lc) over which the polymer material may be conveyed. Section AAshows the channel cross-section, which may have a rectangular profile with height (h) andwidth (w), forming the passage for the polymer melt. The clearance between the screw flightand the barrel wall may be minimized to prevent backflow of the melt and to maintain forwardconveyance. This view explains the geometrical parameters that affect throughput, pressuredevelopment, and melting efficiency inside the extruder.

[00109] In some exemplary embodiments of the present invention, Figure 7(b) illustratesa graphical representation of flow through the nozzle (114). The molten polymer exiting thescrew (110) enters the converging section of the nozzle (114) with an inlet diameter (dN), agiven average velocity (vN), and a characteristic length (LN) of the converging zone. Thematerial is then forced through the smaller exit diameter (de), forming a continuous filament.This diagram highlights the relationship between inlet pressure, nozzle geometry, and extrudatevelocity, which collectively determine the filament diameter and flow rate. The convergingdesign of the nozzle minimizes pressure drop, stabilizes flow, and ensures that the extrudatehas a uniform circular cross-section.

[00110] In some exemplary embodiments of the present invention, the total length of theliquid section may be determined as the sum of the 50 mm straight section and an equivalent122 mm of the tapering section (estimated using volume equivalence), providing a total liquidlength (L, mm) of 172 mm. The screw diameter (D, mm) may be kept at 25 mm. The goal maybe to achieve at least 1 kg / hr deposition rate (M, kg / hr) with the smallest screw possible, atabout 5 RPM screw speed (N, RPM). This mass flow rate may correspond to about 0.0015m3 / hr volumetric flow rate (Q, m3 / hr) or 24,691 mm3 / min, given that the melt density (ρ, kg / m3)may be around 675 kg / m3. For the same, initial nozzle diameter (d, mm) may be taken to be 3mm as a large diameter nozzle may be favorable for low-pressure requirements. The extrudingmaterial will then be pulled using a pulley system to get the desired size of may be 1.7-1.8 mmof the filament. The flight height (H, mm) may be kept around 2 mm, while the nozzle length(l, mm) may be kept to 10 mm.

[00111] Using the before mentioned values, the optimal helix angle (Φ,o) which may bea definitive of the pitch (p, mm; p = π. D.tan Φ), is calculated using Eqn. 1, which results inΦ =19.88o, corresponding to a pitch of 28.4 mm. The pitch may be at 25 mm (Φ=17.65o). Thecorresponding extrusion velocity (vn, mm / s), the associated volumetric (q, mm3 / s) and massflow rate (M, kg / hr), and the melt pressure (P, MPa) may come out to be about 60 mm / s, 416mm3 / s, ~1.02 kg / hr, and 2.1 MPa, respectively, considering a nominal polymer melt viscosity(μ, Pa.s) of 1,000 Pa.s and the screw speed (N) of about 16 RPM. The increase in the requiredscrew speed is due to the reduction in the screw pitch, as more speed is required to match therequired flow rate at a lower pitch. The associated formulas are given in Eqn.s 2-5. Theminimum flight thickness (t, mm) is calculated using the formulae in Eqn. 6, considering theyield strength (Sy, MPa) of the screw material (EN41b) at an elevated temperature of 400 oC,to be 125 MPa. The minimum thickness required may come out to be 0.63 mm, which may beincreased to 4 mm for a safer side. Next, the torque capacity (T, Nm) of the designed screw iscalculated using Eqn. 7. The torque capacity came out to be 3.6 Nm which is well within rangeof the commercially available drive motors (NEMA 34 stepper motor). The correspondingmechanical power (Pm, W) may come out to be ~6 W (T.2πN / 60) and the electrical power (Pe,W) to be 8.6 W, considering 70% conversion.

[00112] In another exemplary embodiment of the present invention, the spooling mayusually be done at a constant linear speed (v, mm / s) which is in conjunction with the extrusionvelocity (vn). The spool may be defined in terms of three dimensions: initial / root diameter (d,mm), final / brim diameter (D, mm), and the width (W, mm). The spooling may start at d, andterminates when it reaches D, i.e. the spool may be completely filled. As the spooling happens,the effective diameter of the spool is a function of the elapsed time (t, s), i.e. d(t). If the totaltime for spooling is (T, s) then, d(0)=d & d(T)=D. As the effective diameter is changing, therotational wrapping speed (w, rad / s) also changes accordingly, so that the relation in Eqn. 8 isalways maintained. The volume of material extruded for a given elapsed time (V(t), mm3), isgiven in Eqn. 9 where, dn (mm) is the wire diameter (here, 1.73-1.75 mm). This volume shouldalso be equal to the volume of material being wrapped over the spool (Eqn. 10). Equating theseand solving for d(t) gives the solution for the spool diameter at a given time (Eqn. 11), whichis further evaluated to determine the spooling speed (N(t), RPM) (Eqn. 12).

[00113] In some exemplary embodiments of the present invention, FIG 8 illustratesschematic diagram of a closed loop feedback mechanism. At step 802, the process initiateswith diameter sensing, where a diameter sensor may measure the actual filament diameter inreal time as the filament is being extruded.

[00114] In some exemplary embodiments of the present invention, at decision step 804,the system determines if the measured diameter is of the required size. This determination maybe performed by a diameter sensor and controller which receives input from the diametersensor. If the filament diameter matches the preset required value, the process may proceed tostep 806, where the controller does nothing further and continues sensing, thereby maintainingthe established extrusion parameters.

[00115] In some exemplary embodiments of the present invention, if at step 804, thefilament diameter is not of the required size, the process may advance to decision step 808,wherein the system may evaluate if the measured diameter is bigger than the requiredspecification. If the diameter is indeed larger, the process may advance to step 810, where thecontroller may increase the puller speed to reduce the filament diameter by stretching the semimolten filament accordingly.

[00116] In some exemplary embodiments of the present invention, if at step 808 themeasured diameter is not bigger (i.e., it is smaller than required), the process may advance tostep 812, where the controller reduces the puller speed to allow a greater volume of material toaccumulate, thereby thickening the filament until the desired diameter is attained.

[00117] In some exemplary embodiments of the present invention, at step 814, the pullerunit may act on the controller's instructions, modifying its speed in response to commands toeither increase or reduce pulling speed, as dictated by the preceding diameter comparison logic.All actions may continue to operate within the described feedback loop until the diametermatches the required size.

[00118] In some exemplary embodiments of the present invention, the process may runcontinuously with the diameter sensor and controller system, represented at step 816, providingongoing real time adjustment of puller speed, thereby ensuring precise control over filamentdiameter and consistent product quality throughout operation.

[00119] In some exemplary embodiment of the present invention, computational toolslike static structural analysis and Heat Transfer (HT) simulations using Finite Element Methods(FEM) may be conducted to predict and evaluate various performance characteristics of criticalcomponents under operational loading and boundary conditions. These analyses may include,, assessments of mechanical behavior, thermal responses, dynamic effects, fluid interactions,and other relevant physical phenomena. This comprehensive evaluation ensures that the designis robust, reliable, and optimized for its intended application.

[00120] In some exemplary embodiments of the present invention, FIG. 9 depicts screwassembly being tested under a buckling load. A horizontal screw extruder experiencescantilevered loads in addition to the normal compressive buckling load due to the melt backpressure. However, the vertical screw design, as presented in this invention, may eliminate thecantilever loads, reducing the total load on the extruder to just the melt back pressure. Thescrew may be designed to withstand the viscous forces of the polymer melt to deliver therequired flow rate against a constant torque. Therefore, only a 2 MPa normal compressive loadmay be applied on the extruder setup, so as to simulate the effect of the polymer melt backpressure. The other end of the screw, which is near the drive motor, may be kept stationary.Respective material may be applied to the individual components, wherein, most of thecomponents may be metallic, made of Stainless Steel, aluminium, brass or the like.

[00121] In some exemplary embodiments of the present invention, FIG 9A illustratesthe meshed profile of the extruder screw utilized for structural analysis. The screw assembly,may be composed primarily of stainless steel and other metallic materials, is modeled with afine mesh of 0.5 mm with approximately 363,000 elements. This detailed meshing ensuresaccurate finite element simulations by discretizing the screw geometry and thereby enablingcomprehensive mechanical evaluation under the proposed loading conditions. Such precisemeshing is essential for assessing the structural integrity of the screw under operational stressesassociated with filament extrusion and buckling loads.

[00122] In some exemplary embodiments of the present invention, FIG. 9B illustratesthe stress distribution on the extruder screw under a normal compressive load of 2 MPa,simulating polymer melt back pressure. The analysis, displayed at a deformation scale of 7.6for visual clarity, confirms a uniform stress distribution along the length of the screw. Notably,there are no stress concentration points or signs of yielding, as the stresses fall within region a,indicating that the yield strength is within the desired range of 1.143e+00 to 6.257e+06 N / m^2,thereby evidencing the robustness of the vertical screw design. The simulation verifies that theapplied operational load is substantially lower than the material yield strength, underscoringthe safe mechanical performance of the screw assembly. Accompanying this analysis is agrayscale bar representing yield strength, segmented for easier interpretation: region a(1.143e+00 to 6.257e+06 N / m^2) corresponds to low yield strength, region b (8.343e +06 to1.460e + 07 N / m^2) represents moderate yield strength, and region c (1.669e + 07 to 2.086e +07 N / m^2) indicates high yield strength.

[00123] In some exemplary embodiments of the present invention, FIG 9C illustratesthe displacement plot of the extruder screw under the same applied buckling load, visualizedat a deformation scale of 1. The accompanying scale is divided into three distinct regions forclarity: 'e', 'f', and 'g'. Region 'g' represents the lowest displacement range fromapproximately 1.000e-30 mm to 9.289e-04 mm, corresponding to the fixed and least affectedparts of the screw near the drive motor end. Region 'f' covers the middle displacement rangefrom about 1.393e-03 mm up to 2.787e-03 mm, describing moderate elastic deformationoccurring primarily along the shaft and mid-flight zones. Region 'e' signifies the highestdisplacement range from approximately 3.251e-03 mm to the maximum displacement value of4.644e-03 mm observed at the free end or highly loaded sections of the screw. These resultscollectively confirm that the screw design exhibits minimal deformation and is structurallysufficient to withstand the anticipated operational and buckling forces.

[00124] In some exemplary embodiments of the present invention, FIG. 10 depicts theresults of the structural analysis performed on the frame of the extrusion system. Specifically,it includes (a) the meshed profile used for computational simulation, (b) the stress-distributionmap under applied loads with deformation scale set to 194, and (c) the displacement plot withdeformation scale set to 1, illustrating the overall deformation response.

[00125] In some exemplary embodiments of the present invention, FIG. 10A illustratesthe meshed profile of the frame. The stainless steel (SS) sheet metal frame may includeinterlocking joints and may be discretized with a 2 mm mesh size, with approximately 80,000elements across its surfaces. The mesh may enable the finite element simulation of the frame'sbehavior under a resultant load of 113 N applied at contact points of subcomponents. Thebottom part of the frame may be treated as a fixed geometry, establishing robust boundaryconditions for stress and displacement analyses.

[00126] In some exemplary embodiments of the present invention, FIG. 10B presentsthe stress-distribution map of the frame as obtained from computational analysis, with adeformation scale of 194 applied for clear visualization. The stress profile is observed to beboth uniform and symmetric as it falls within the z region having yield strength between0.000e+00 to 4.128e+07 N / m^2 indicating that the frame can carry the applied loads safelywithout yielding or permanent deformation. The accompanying greyscale colour bar issegmented for interpretation: region x ranges from 1.101e + 08 to approximately 1.376e+08N / m^2, which means our frame cannot carry the applied loads safely without yielding orpermanent deformation; region y ranges from approximately 5.504e + 07 to 9.631e+07 N / m^2,which is acceptable to some extent but still requires caution ; and region z covers values up toapproximately 0.000e + 00 to 4.128e + 07 N / m^2, which is perfectly safe with minimal risk offailure. The analysis may confirm the absence of stress concentration points or yielding,verifying the strength and reliability of the frame to safely support all functioning componentsunder operational loads.

[00127] In some exemplary embodiments of the present invention, FIG. 10(c) illustratesthe displacement plot of the frame under loading. The stress values fall predominantly withinregion z (approximately 1.000e-30 to 1.194e-01 mm), which indicates a fully safe conditionwithout risk of yielding. A peak vertical deflection of ~0.4 mm was observed at the barrel-nozzle-heater assembly location, but this displacement is minimal and does not affect thestructural integrity of the frame, confirming that the frame can safely withstand the appliedloads and component weights. The accompanying greyscale colour bar is segmented forinterpretation: region x ranges from 3.184e-01 to 3.979e-01 mm, region y ranges from 1.592e01 to 2.786e-01, z ranges from 1.000e-30 to 1.194e-01 mm.

[00128] In some exemplary embodiments of the present invention, a transient heattransfer (HT) analysis i.e. thermal simulation results are provided as illustrated in FIG. 11. Theanalysis evaluates temperature distribution across the assembled filament extrusion systemover 3600 seconds (1 hour), with outputs at 600-second (10-minute) intervals. An ambienttemperature of 28 °C is applied, while barrel heater regions are fixed at 450 °C, representingthe upper extrusion range of PEEK. Forced cooling is applied near the hopper and motorcoupling to simulate external fans. The model uses a 2.7 mm mesh size, generating about226,000 elements. Results show the hopper region remains below the glass transitiontemperature of PEEK (~150 °C), ensuring effective heat extraction and uninterrupted feedflow.

[00129] In some exemplary embodiments of the present invention, Figure 11Aillustrates the barrel and nozzle regions maintained at the extrusion temperature of 450 °C. Thisresult confirms that the applied heating zones successfully achieve the target thermal profilefor processing high-performance thermoplastics such as PEEK, ensuring proper melting priorto extrusion.

[00130] In some exemplary embodiments of the present invention, Figure 11B illustratesthe throat area near the hopper (106), which is maintained under forced cooling conditions. Thecooling prevents heat conduction from the barrel (108) into the hopper region, therebymaintaining the incoming polymer feed in solid state for uninterrupted gravity flow into thescrew (110).

[00131] In some exemplary embodiments of the present invention, Figure 11C illustratesthe coupler region (124) maintained under forced cooling conditions. This result demonstratesthe effectiveness of the cooling arrangement in protecting the mechanical coupling betweenthe screw (110) and the drive motor (104) from excessive thermal exposure, which couldotherwise reduce performance and service life.

[00132] In some exemplary embodiments of the present invention, Figure 11Dillustrates the generated mesh profile used for the thermal simulation. The meshing employsan average element size of approximately 2.7 mm, producing a total of about 226,000 elements.This meshing resolution ensures adequate accuracy in the transient heat transfer analysis whilemaintaining computational efficiency.

[00133] In some exemplary embodiments of the present invention, Figure 11E illustratesthe overall temperature distribution in the assembled system at the final time step of the analysis(3600 s / 1 hr). A steady-state condition is observed, with the heater-barrel region stabilized atthe defined extrusion temperature (up to ~450 °C). The areas represented as region r (rangingfrom approximately 2.485e+01 °C to 1.533e+02 °C) correspond to the low-temperature zones,indicating that the frame and hopper remain well below critical thresholds such as the glasstransition temperature of PEEK. This confirms effective thermal isolation of the heated sectionfrom the rest of the structure. The accompanying grayscale color bar is divided into segmentsfor easier interpretation. Region p corresponds to high temperatures, ranging from 3.675e + 02to 4.532e +02 Celsius. Region q represents moderate temperatures, ranging from 1.962 + 02 to3.247e+02 Celsius, while region r indicates lower temperatures, ranging from 2.485e +01 to1.533 +02 Celsius.

[00134] In another exemplary embodiment of the present invention, FIG.12 depicts themethod (1200) of the present invention, that operates on the principle of thermoplasticextrusion, where raw polymer material (usually in pelletized or granular form) may be melted,shaped, and cooled into continuous filament suitable for FFF 3D printing. At block (1202), theprocess may begin with setting the barrel temperatures using external heaters arranged inmultiple heating zones to achieve the required thermal profile for polymer melting. At block(1204), the thermoplastic granules or pellets may then be fed into the heated barrel via gravityfeeding through the hopper. Baffles may further be installed over the throat area to induceturbulence for easy flow and choking avoidance. At block (1206), the screw rotation mayconvey the polymer material forward while simultaneously applying mechanical shear andthermal energy, gradually melting the polymer and extruding the melt through the nozzle..External heaters, mounted on the barrel, may require to provide the necessary energy for phasechange of the polymer. The pineapple screw feature at the end, may allow for proper mixingof the polymer melt (in case of multi-material and / or multi-color extrusions) before the melt isextruded out of the attached nozzle. The molten polymer when pushed through a nozzle maydefine the initial filament diameter (about 3 mm in this case).

[00135] Once extruded, the semi-solid filament may enter a cooling zone, involving aircooled fans, to solidify the filament into a stable cylindrical form. At block (1208), the filamentmay be drawn forward by puller rollers, while its diameter may continuously be sensed by adiameter sensing unit positioned downstream of the nozzle. The filament may then be pulledby a set of calibrated puller rollers, which may control the filament diameter by adjusting thedraw speed pulling faster makes the filament thinner, while pulling slower makes the filamentthicker. The diameter sensor may continuously monitor the filament size, and a feedbackcontrol loop adjusts the puller speed in real-time to maintain the target diameter. The entireprocess may be controlled by a microcontroller, which regulates heating elements, reads sensorinputs, and drives motors via electronic drivers. The Switched-Mode Power Supply (SMPS)may provide the necessary DC power to all system components. At block (1210) the controlledand continuous operation may result in a uniform, high-quality filament that can be wound ontoa spool for later use in FFF 3D printers.

[00136] In some exemplary embodiments of the present invention, a method (1300) forproducing filaments using a filament extrusion system is provided as illustrated in FIG. 13. Themethod comprises a sequence of operations that allow transformation of thermoplastic materialinto continuous filament with controlled dimensions.

[00137] In some exemplary embodiments of the present invention, at block (1302),virgin or recycled thermoplastic material may be fed into an extrusion unit. The extrusion unitmay include a hopper that may be configured with a funnel geometry. The funnel geometry ofthe hopper may direct the thermoplastic material toward the screw input and minimizesmaterial bridging or clogging. The hopper may also include internal baffles that promotemixing of the incoming thermoplastic material, thereby improving consistency of feed andensuring that the flow of material toward the screw is maintained.

[00138] In some exemplary embodiments of the present invention, at block (1304), thethermoplastic material may be conveyed and melted using a vertically aligned single-screwextruder that may be positioned directly below the hopper. The vertical alignment of the screwfacilitates gravity-assisted feeding of the thermoplastic material into the screw channel. Thescrew may incorporate a pineapple-cut mixing geometry that enhances the breakdown andblending of material during the melting process, thereby supporting a more uniform meltquality.

[00139] In some exemplary embodiments of the present invention, at block (1306),torque may be transmitted from a motor to the screw while maintaining proper axial alignment.A double coaxial thrust bearing assembly may be arranged between the motor and the screw toabsorb axial forces generated during extrusion. This configuration may prevent direct axialloading on the motor shaft and allows smooth rotational motion of the screw, therebyimproving the durability and stability of the extrusion process.

[00140] In some exemplary embodiments of the present invention, at block (1308),controlled heating may be applied through multiple heating zones to raise the temperature ofthe thermoplastic material to its molten state. The heating may be delivered by external heatersmounted on the barrel, which encloses the screw. These heating zones may be individuallycontrolled to provide a gradual temperature profile along the length of the screw. In theextrusion end of the screw, a pineapple-cut mixing section promotes mixing of the meltedthermoplastic material and supports uniform temperature distribution prior to extrusion.

[00141] In some exemplary embodiments of the present invention, at block (1310), themolten thermoplastic material may be forced through a nozzle mounted at the end of the barrel.The nozzle may provide a defined opening that shapes the existing melt into a continuousfilament. The initial diameter of the filament may generally be based on the size of the nozzleopening, and the nozzle design ensures steady flow of material into filament form.

[00142] In some exemplary embodiments of the present invention, at block (1312), theextruded filament may pass through a cooling zone. Within the cooling zone, the filament maybe exposed to conditions that may reduce its temperature sufficiently to cause solidification.This cooling process may allow the filament to retain the shape imparted by the nozzle andstabilizes its dimensions for further handling.

[00143] In some exemplary embodiments of the present invention, at block (1314), thediameter of the cooled filament may be measured using a diameter sensing unit that may bepositioned downstream of the nozzle. The sensing unit monitors the filament as it moves alongthe processing path and generates information relating to the actual diameter of the filament.This measurement may provide a basis for evaluating whether the filament conforms to thedesired target dimensions.

[00144] In some exemplary embodiments of the present invention, at block (1316),adjustments may be made to the puller unit that draws the filament forward. The puller rollersof the puller unit may be speed-controlled according to a closed-loop feedback mechanism.The feedback mechanism may use the measured filament diameter to determine whether anadjustment in roller speed is required. When deviation from the predefined filament diameteroccurs, the roller speed may be increased or decreased to restore dimensional accuracy.

[00145] In some exemplary embodiments of the present invention, at block (1318), thefilament may be collected on a spooling unit. The spooling unit may further wind the filamentonto a spool in an organized manner. This step may allow for convenient storage,transportation, and later use of the filament in downstream applications such as threedimensional printing.

[00146] An exemplary advantage of the system and method described herein is that thesystem and method ensure consistent filament quality and diameter while allowing for efficient,continuous production. Users can shred failed prints into granules and feed them back into thesystem, promoting a circular economy approach in 3D printing. Designed for ease of use,portability, and aesthetic appeal, the entire setup is housed within a single compact mainframe.The system is fully operable by a single user and requires no specialized training or externalintervention, making the system ideal for makerspaces, research labs, educational institutions,and hobbyists alike.

[00147] An important advantage of the present invention is that the embodimentsdescribed herein provide Analytical Modeling: The formulas mentioned hereinabove serves asthe basis for designing similar extrusion systems of comparable capacities.

[00148] An important advantage of the present invention is that the embodimentsdescribed herein provide a Hopper Spill Cover. This sheet metal part is added over the hopperto prevent over spillage of the feedstock pellets and also provide safety to the user by restrictingthe access to the moving / heated parts.

[00149] Another important advantage of the present invention is that the embodimentsdescribed herein provide a unique feature of external hopper cooling, which is installed to keepthe hopper (and the pellets inside), below the glass-transition temperature.

[00150] An other important advantage of the present invention is that the screw designalso features a pineapple cut mixing zone at the end, referred to as the pineapple mixer. About10 flights in either direction (5 clockwise and 5 anti-clockwise) run across this section toprovide proper mixing of the polymer melt.

[00151] An other important advantage of the present invention is that the design featuresdiameter sensing of the extruded filament using a Hall effect sensor, to keep the filament sizewithin the required range, e.g. 1.7-1.8 mm for 3D printing filaments.

[00152] Another important advantage of the present invention is that the system canhandle multi-material feedstock which includes multiple thermoplastic blends and reinforcedblends of thermoplastics with metal, ceramics and resin powders.

[00153] Other important advantages of the present invention are that the embodimentsdescribed herein provide:

[00154] Vertical Screw Design: The presented design has a vertical screw arrangement,where the screw axis and extrusion axis are collinear, making the system more accurate. Thisarrangement provides an axis-symmetric / uniform loading onto the mounting bearings,providing uniform wear and high reliability.

[00155] Double Bearing Arrangement: The presented design utilizes two co-axiallyinverted thrust bearings. This arrangement aids in restricting any axial movement of the screw,either due to back pressure by the polymer melt or the self-weight and normal thrust by thescrew-drive system. This ensures high accuracy and longevity of the system.

[00156] Structural Uniformity: The presented design has a symmetric design, enablinguniform structural integrity and stress distribution. The components of the extrusion system areuniformly mounted on all 4 sides, using thin-sheet metals and gusset, making the systemlightweight and robust.

[00157] Efficient Hopper Design: The machine presents an efficient hopper design formaximum space utilization and material holding capacity. Unlike traditional hoppers which arecircular and axis-symmetric, the presented design has a square shaped hopper which provideseasier manufacturing, better mounting & heat transfer and higher space efficiency than thecircular hopper designs.

[00158] Mixing Baffles: Inside the hopper, 2 metal rods are present which are placedradially apart for load balancing. These rods act as baffles which provide extra mixing andhomogeneity to the thermoplastic feedstock.

[00159] Novel Screw Design: The screw design is unique and explicitly designed formaterial extrusion applications. Unlike the injection moulding screws which offer small pitchwith three discrete zones and high pressure capacity, the designed screw uses a single flight,high pitch design that offers higher flow rates (up to 1 kg / hr at just 3 RPM) with reduced backpressure.

[00160] Orthogonal Spooling: The extruded filament is made to pass over a positionerarm that bends the filament tangential to the diameter of spool, thereby aligning the extrudedfilament inline with the spooling axis. This single directional turn helps minimize mechanicalstress and material loss by reducing the number of bends the filament experiences beforewinding. The positioner arm moves back and forth across the set width of the spool with acalculated speed with respect to the speed of spooling for said alignment.

[00161] Modular Design: The overall extruder-spooler design is modular where boththe unit can be dis-assembled and placed separately for better space usage and storage. Thisway, materials which require longer cooling can also be processed with this arrangement.

[00162] It will be apparent from the foregoing that while particular forms of theinvention have been illustrated and described, various modifications can be made withoutdeparting from the scope of the invention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.REFERENCE NUMERLASElement Reference NumeralFilament Extrusion System 100Control Unit 101Main Frame 102Sensor(s) 103Drive Motor 104Hopper 106Barrel 108Screw 110Heating Zone 112Nozzle 114Cooling Zone 116Diameter Sensing System 118Puller Unit 120Spooling Unit 122Coupling (Oldham) 124Thrust Bearing 126Pineapple Mesh 128Threading 130Spool Shaft 132Positioner Arm 134Control Unit integrated with the PullerUnit136Wing Nut 138Clutch Mechanism 140Motor 142Gear 144

Claims

1. A filament extrusion system, the system comprising: - an extrusion unit comprising: a vertically oriented screw extruder configured to melt and convey thermoplastic material; a hopper mounted above the screw extruder, having a funnel geometry and internal baffles to facilitate mixing and flow, configured to feed thermoplastic material; a motor coupled to the screw and a double coaxial thrust bearing assembly, arranged in between the screw and motor, to transmit torque while maintaining axial alignment; a barrel enclosing the screw, the barrel comprising multiple heating zones with external heaters configured to melt the polymer and a pineapple-cut mixing section at the extrusion end of the screw; a nozzle mounted at the end of the barrel for extruding the melted thermoplastic into a filament of diameter based on nozzle opening size; a cooling zone configured to solidify the extruded filament; - a diameter sensing unit positioned downstream of the nozzle configured to measure the extruded filament diameter; - a puller unit positioned downstream of the diameter sensing unit, controlled by a closed-loop feedback mechanism based on diameter measurements, to maintain the filament diameter as predefined by a user; - a spooling unit configured to collect the filament; and - a main frame for housing the extrusion unit, the diameter sensing unit, the puller unit and the spooling unit.

2. The system as claimed in claim 1, wherein the screw extruder comprises a single-flight, high-pitch screw configured to mechanically convey the material forward at low rotational speeds in the range of 3-16 RPM and to deliver at least 1 kg / hr extrusion rate.

3. The system as claimed in claim 1, wherein the hopper is constructed from laser-cut and welded metal sheets, preferably stainless steel and includes a spill-proof cover with a trapezoidal slot for safe user access and refilling and the hopper has a funnel geometry.

4. The system as claimed in claim 1, wherein the motor is coupled to the screw via an Oldham's coupling.

5. The system as claimed in claim 1, wherein the pineapple mixing section of the screw comprises alternating clockwise and counter-clockwise helical grooves to facilitate multi-material blending and homogenization.

6. The system as claimed in claim 1, wherein the double thrust bearing assembly comprises coaxially aligned, oppositely facing NKX-15 needle-roller combination bearings to handle axial loads induced by extrusion pressure and screw weight.

7. The system as claimed in claim 1, wherein the nozzle is made up of materials selected from a group consisting of brass, nitrided steel, stainless steel and tool steel, and the filament exiting the nozzle is subjected to forced convection air cooling in the cooling zone.

8. The system as claimed in claim 1, wherein the filament diameter sensing unit is a Halleffect or optical sensor configured to operate in a closed-loop control with the puller speed to achieve a filament diameter between 1.7 mm and 1.8 mm and measures the extruded filament diameter in real time.

9. The system as claimed in claim 1, wherein the spooling unit comprises a dynamically variable speed mechanism to maintain constant filament linear velocity and is designed to dynamically adjust rotational speed based on real-time calculation of spool diameter and filament feed rate to maintain constant linear velocity ensuring even winding.

10. The system as claimed in claim 1, wherein the filament is redirected tangential to the diameter of spool via a positioner arm to align with the spooling axis, increasing residual stresses and improving filament quality.

11. The system as claimed in claim 1, further comprising a processor unit connected to the heating zones, diameter sensing unit, puller unit, and spooling unit, wherein the processor is configured to calculate filament dimensional accuracy based on real-time sensor input; and wherein the processor executes control algorithms including PID control for heater zones, diameter regulation, and motor speed adjustments.

12. The system as claimed in claim 1, wherein the diameter sensing unit measures the filament diameter in real-time and sends the data to the processor, the processor compares the measured value with the value of the filament diameter predefined by a user and calculates the difference between the predefined value and the measured value.

13. The system as claimed in claim 13, wherein the processor is configured to reduce the speed of the puller to allow more material to accumulate when the measured diameter is smaller than the predefined value and / or the processor is configured to increase the speed of the pullers to stretch the filament and reduce the diameter of the filament when the diameter is larger than the predefined value.

14. The system as claimed in claim 1, further comprising a cooling unit with forced air fans directed at the hopper to prevent premature softening of the feedstock by maintaining the temperature below the material's glass transition temperature .

15. The system as claimed in claim 1, wherein the system is modular and comprises detachable extruder and spooler units, allowing for extended filament cooling paths or independent operation.

16. The system as claimed in claim 1, wherein the system is powered by a switched-mode power supply and includes emergency stop buttons and safety relays to cut off power in case of overheating, motor stalling, or sensor failure.

17. A method for producing filaments using filament extrusion system, comprising: - feeding virgin or recycled thermoplastic material into an extrusion unit comprising a funnel geometry hopper and internal baffles to facilitate mixing and flow; - conveying and melting the thermoplastic material using a vertically aligned singlescrew extruder mounted below the hopper with pineapple-cut mixing geometry; - transmitting torque while maintaining axial alignment between a motor coupled to the screw and a double coaxial thrust bearing assembly, arranged in between the screw and motor; - applying controlled heating through multiple heating zones including multiple external heaters mounted on the barrel, enclosing the screw, to melt the thermoplastic material and mixing the melted material in a pineapple-cut mixing section at the extrusion end of the screw; - extruding the molten material through a nozzle mounted at the end of the barrel to form a filament of diameter based on nozzle opening size; - cooling the extruded filament in a cooling zone to solidify the extruded filament; - measuring the diameter of the extruded filament using a diameter sensing unit positioned downstream of the nozzle; - adjusting the speed of puller rollers of a puller unit based on a closed-loop feedback mechanism, based on the measured filament diameter to maintain dimensional accuracy as predefined by a user; - collecting the filament on a spooling unit.

18. The method as claimed in claim 18, further comprising calculating optimal extrusion parameters including screw pitch, extrusion pressure, and motor torque using analytical models for flow rate, viscosity, and material properties.

19. The method as claimed in claim 18, wherein the polymer feedstock melts progressively along the barrel with combination of mechanical shear and thermal energy.

20. The method as claimed in claim 18, wherein the hopper is constructed from laser-cut and welded metal sheets, preferably stainless steel and includes a spill-proof cover with a trapezoidal slot for safe user access and refilling and the hopper has a funnel geometry.

21. The method as claimed in claim 18, wherein the screw extruder comprises a single-flight, high-pitch screw configured to mechanically convey the material forward at low rotational speeds in the range of 3-16 RPM and to deliver at least 1 kg / hr extrusion rate.

22. The method as claimed in claim 18, wherein the pineapple mixing section of the screw comprises alternating clockwise and counter-clockwise helical grooves to facilitate multi-material blending and homogenization.

23. The method as claimed in claim 18, wherein the double thrust bearing assembly comprises coaxially aligned, oppositely facing NKX-15 needle-roller combination bearings to handle axial loads induced by extrusion pressure and screw weight.

24. The method as claimed in claim 18, wherein the nozzle may be made up of materials selected from a group consisting of brass, nitrided steel, stainless steel, and tool steel, and the filament exiting the nozzle is subjected to forced convection air cooling in the cooling zone.

25. The method as claimed in claim 18, wherein the filament diameter sensing unit is a Halleffect or optical sensor configured to operate in a closed-loop control with the puller speed to achieve a filament diameter between 1.7 mm and 1.8 mm and measures the extruded filament diameter in real time.

26. The method as claimed in claim 18, wherein the spooling unit comprises a dynamically variable speed mechanism to maintain constant filament linear velocity that dynamically adjusts rotational speed based on real-time calculation of spool diameter and filament feed rate to maintain constant linear velocity ensuring even winding.

27. The method as claimed in claim 18, wherein the filament is redirected tangential to the diameter of spool via a positioner arm to align with the spooling axis, increasing residual stresses and improving filament quality, and wherein the positioner arm moves back and forth across the set width of the spool with a calculated speed with respect to the speed of spooling for said alignment.

28. The method as claimed in claim 18, further comprising a processor unit connected to the heating zones, diameter sensing unit, puller unit, and spooling unit, wherein the processor is configured to calculate filament dimensional accuracy based on real-time sensor input; and wherein the processor executes control algorithms including PID control for heater zones, diameter regulation, and motor speed adjustments.

29. The method as claimed in claim 18, wherein the diameter sensing unit measures the filament diameter in real-time and sends the data to the processor, the processor compares the measured value with the value of the filament diameter predefined by a user and calculates the difference between the predefined value and the measured value.

30. The method as claimed in claim 31, wherein the processor is configured to reduce the speed of the puller to allow more material to accumulate when the measured diameter is smaller than the predefined value and / or the processor is configured to increase the speed of the pullers to stretch the filament and reduce the diameter of the filament when the diameter is larger than the predefined value.

31. The method as claimed in claim 18, further comprising a cooling unit with forced air fans directed at the hopper to prevent premature softening of the feedstock by maintaining the temperature below the material's glass transition temperature.

32. The method as claimed in claim 18, wherein the system is powered by a switched-mode power supply and includes emergency stop buttons and safety relays to cut off power in case of overheating, motor stalling, or sensor failure.