WO2015039130A1

WO2015039130A1 - Rheological modification of extrusions for use in additive manufacturing

Info

Publication number: WO2015039130A1
Application number: PCT/US2014/055936
Authority: WO
Inventors: Lance R. PICKENS
Original assignee: Madesolid, Inc.
Priority date: 2013-09-16
Filing date: 2014-09-16
Publication date: 2015-03-19

Abstract

An extrusion apparatus reduces swelling in an extruded material. The apparatus is configured to reduce swelling by inducing shear stress in an at least partially molten material (e.g., polymers, metals, glasses, and/or other materials) that is being extruded through a nozzle. The apparatus is configured to induce the shear stress in the at least partially molten material via one or more oscillating transducers coupled with the nozzle.

Description

RHEOLOGICAL MODIFICATION OF EXTRUSIONS FOR USE IN ADDITIVE MANUFACTURING

FIELD

(01) This disclosure relates to an apparatus and method to reduce swelling in an extruded material.

BACKGROUND

(02) Additive manufacturing, commonly known as 3D Printing, often employs extrusion to construct objects. Controlling the extrusion is critically important during 3D printing. After extrusion from a typical extrusion nozzle, various materials exhibit "swell". A final diameter, for example, of the output extrudate may be larger than the diameter of an exit annulus of an extrusion nozzle. These dimensional changes increase undesirable variability during 3D printing.

SUMMARY

(03) One aspect of the disclosure relates to an extrusion apparatus. The extrusion apparatus may comprise a nozzle, one or more transducers, and/or other components. The nozzle may form a nozzle pathway to conduct an at least partially molten material in an extrusion direction from an input end to an output end. The nozzle pathway may have a first larger cross-sectional area at the input end and a second smaller cross-sectional area at the output end.

(04) The one or more transducers may be coupled with the nozzle. The transducer(s) may be configured to oscillate such that vibrational energy from the oscillation is received by the nozzle and causes changes in a temperature, a pressure, a volume, and/or other parameters within the nozzle pathway. (05) The changes in the temperature, the pressure, the volume, and/or other parameters within the nozzle pathway may induce changes in rheological parameters of the at least partially molten material. The rheological parameters may include a viscosity of the at least partially molten material, for example. The changes in the rheological parameters of the at least partially molten material may reduce swelling of the partially molten material after extrusion. Such swelling may comprise an increase in a cross-sectional area of the at least partially molten material to a third cross-sectional area that is larger than the second cross- sectional area of the nozzle pathway.

(06) Another aspect of the disclosure relates to an extrusion method. The extrusion method may comprise forming a nozzle pathway with a nozzle to conduct an at least partially molten material in an extrusion direction from an input end to an output end. The nozzle pathway may have a first larger cross-sectional area at the input end and a second smaller cross-sectional area at the output end.

(07) The extrusion method may comprise receiving vibrational energy from an oscillating transducer coupled with the nozzle. The vibrational energy from the oscillation may be received by the nozzle and cause changes in one or more of a temperature, a pressure, a volume, and/or other parameters within the nozzle pathway.

(08) The changes in one or more of the temperature, the pressure, the volume, and/or the other properties within the nozzle pathway may induce changes in rheological parameters of the at least partially molten material. The rheological parameters may include a viscosity of the at least partially molten material, for example. The changes in the rheological parameters of the at least partially molten material may reduce swelling of the partially molten material after extrusion. Such swelling may comprise an increase in a cross-sectional area of the at least partially molten material to a third cross-sectional area that is larger than the second cross-sectional area of the nozzle pathway.

(09) These and other objects, features, and characteristics of the system and/or method disclosed herein, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRA WINGS

(10) FIG. 1 illustrates an extrusion apparatus configured to reduce swelling in an extruded material.

(1 1) FIG. 2 illustrates swelling in an extruded material

(12) FIG. 3 illustrates an extrusion method for reducing swelling after extrusion. DETAILED DESCRIPTION

(13) FIG. 1 illustrates an extrusion apparatus 10 configured to reduce swelling in an extruded material. In polymer extrusions, for example, swelling may result from molecular interactions that prevent adequate relaxation of polymer chains before and/or during extrusion through a nozzle. Swelling may include an increase in one or more dimensions, and/or a change in shape, of the extrudate. Swelling may include an increase in a cross-sectional area of the extruded material compared to the cross-sectional area of the extruded material at an output end of the nozzle (while still in the nozzle and/or just after exiting the nozzle). Swelling may include a material in a higher energy state (e.g., stretched polymer chains) returning to a lower energy state (e.g., relaxed polymer chains). Stretched polymer chains in an extruded polymer, for example, may swell (e.g., relax) to their pre-extrusion size and/or shape after extrusion when they are no longer constrained by the nozzle.

(14) For example, FIG. 2 illustrates swelling in an extruded material 50.

Extruded material 50 is being extruded in an extrusion direction 52 through a nozzle 54. Extruded material 50 has a first diameter 56 while still within and/or just after exiting nozzle 54, but swells to a second larger diameter 58 over time. An amount of swell may be determined based on the difference between first diameter 56 and second diameter 58.

(15) Returning to FIG. 1 , apparatus 10 is configured to reduce swell by inducing shear stress in an at least partially molten material (e.g., polymers, metals, glasses, and/or other materials) that is being extruded through a nozzle 1 2.

Apparatus 1 0 is configured to induce the shear stress in the at least partially molten material via one or more oscillating transducers 14 coupled with nozzle 1 2. The oscillation direction, amplitude, frequency, and/or other parameters of the one or more oscillating transducers 14 may be controlled by a controller 18.

Vibrational energy from a transducer 14 may cause changes in the volume, pressure, temperature, and/or other parameters within nozzle 12. The changes in the parameters within nozzle 12 may induce the shear stress in the at least partially molten material, causing rheological changes in the at least partially molten material.

(16) For example, shear thinning behavior may occur in an at least partially molten polymer. The induced shear stress may cause a decrease in the apparent viscosity of the at least partially molten polymer. The relaxation time of the at least partially molten polymer may be shortened, thereby increasing relaxation during an otherwise identical extrusion process (e.g., over the same period of time), and reducing swell. By reducing swell and providing the ability to control the shear stress applied via transducer 14, apparatus 10 may facilitate fine-tuned control over final part production (e.g., apparatus 10 may reduce warping) during additive manufacturing. In some implementations, apparatus 10 may include nozzle 12, transducer 14, one or more sensors 16, controller 18, extrusion equipment 20, and/or other components.

(17) Nozzle 12 may form a nozzle pathway 30 to conduct an at least partially molten material in an extrusion direction 32 from an input end 34 to an output end 36 of nozzle 12. The at least partially molten material may be fed to nozzle 1 2 via extrusion equipment 20. Nozzle pathway 30 may have a first larger cross- sectional area at input end 34 and a second smaller cross-sectional area at output end 36. Input end 34 may be removably and/or fixedly coupled with extrusion equipment 20. In some implementations, nozzle pathway 30 may be configured to conduct at least partially molten polymer materials, metal materials, glass materials, ceramic materials, and/or other materials during extrusion.

(18) In some implementations, nozzle 12 may include one or more valves configured to control the flow of the extruded material. The one or more valves may be manually controlled by users of apparatus 10, controlled by controller 18, and/or controlled via other methods. In some implementations, the one or more valves may be configured to control the flow of extruded material based on the parameters of the extruded material. For example, the one or more valves may be configured to allow the flow of extruded material responsive to a viscosity of the extruded material breaching a viscosity threshold. The viscosity threshold may be determined by the mechanical shape, and/or other features of the valves, for example.

(19) The description of nozzle 1 2 above and the illustration of nozzle 12 in FIG. 1 is not intended to be limiting. Nozzle 12 may have any form factor (e.g., size, shape, etc.) that allows it to function as described herein. For example, nozzle pathway 30 may have a circular cross-section, a square-shaped cross-section, and/or other cross-sections. In some implementations, nozzle pathway 30 may have a first cross-sectional shape (e.g., circular) at input end 34, and a second cross-sectional shape (e.g., cross-shaped) at output end 36. Nozzle 12 may be formed by machining, molding, and/or other fabrication processes. In some implementations, nozzle 12 may be heated. The nozzle heater may be included in extrusion equipment 20. The nozzle heater may be controlled by controller 18.

(20) Transducer 14 may be coupled with nozzle 12. In some implementations, transducer 14 may be located at or near output end 36 of nozzle 12. Transducer 14 may be configured to oscillate such that vibrational energy from the oscillation is received by nozzle 1 2. The vibrational energy may cause changes in a temperature, a pressure, a volume, and/or other parameters within nozzle pathway 30. For example, oscillations from transducer 14 may cause a corresponding cyclical change in an orifice distance 44 at output end 36 of nozzle 12 (causing a change in the volume of nozzle pathway 30). The changes in the temperature, the pressure, the volume, and/or other parameters within nozzle pathway 30 may induce shear stress in the at least partially molten material. The changes in the temperature, the pressure, the volume, and/or other properties within the nozzle pathway may induce changes in rheological parameters (e.g., due to the shear stress) of the at least partially molten material. The rheological parameters may include a viscosity of the at least partially molten material, a temperature, a pressure, a flow rate, a molecular weight, a density, and/or other rheological parameters, for example. The changes in the rheological parameters of the at least partially molten material may reduce swelling of the partially molten material after extrusion. Transducer 14 may be and/or include a piezoelectric transducer, a speaker, a tactile transducer, an actuator, an electroactive polymer, a motor, a piston, and/or other transducers.

(21) In some implementations, transducer 14 may oscillate in one or more oscillation directions. Transducer 14 may be configured such that the direction of oscillation is substantially parallel to extrusion direction 32. In some

implementations, transducer 14 may be configured such that the direction of oscillation is substantially perpendicular to extrusion direction 32. In some implementations, the direction of oscillation may be a direction other than parallel and/or perpendicular to extrusion direction 32.

(22) In some implementations, transducer 14 may be formed by two or more individual transducers. In some implementations, the two or more individual transducers may be configured to oscillate in similar directions, with similar amplitudes and/or frequencies relative to each other. In some implementations, the two or more individual transducers may be configured to oscillate in unique directions, with unique amplitudes and/or frequencies relative to each other. For example, a first transducer 14 may oscillate in a direction that is substantially perpendicular to the extrusion direction with a first amplitude at a first frequency. A second transducer 14 may oscillate in direction that is substantially parallel to the direction of extrusion with a second amplitude at a second frequency. In some implementations, the individual transducers may be controlled (e.g., via controller 18) to oscillate simultaneously and/or at different times. The individual

transducers may be controlled such that the vibrational energy produced by one of the transducers compliments and/or enhances the vibration energy produced by the other transducers.

(23) Sensors 1 6 may be configured to generate output signals related to the rheological parameters of the at least partially molten material within nozzle pathway 30. The rheological parameters of the at least partially molten material may include a viscosity, a temperature, a pressure, a flow rate, a molecular weight, a density, and/or other rheological parameters. In some implementations, sensors 16 may be configured to generate output signals related to the vibrational energy received by nozzle 12 and/or the oscillations from transducer 14. In some implementations, sensors 16 may include pressure sensors and/or other force sensors, temperature sensors, flow meters, viscometers, voltmeters,

accelerometers, and/or other sensors.

(24) Sensors 1 6 may comprise one or more sensors that measure such parameters directly (e.g., through fluid communication with the at least partially molten material in nozzle pathway 30, through direct communication with transducer 14). Sensors 16 may comprise one or more sensors that generate output signals related to the one or more parameters indirectly. For example, sensors 16 may comprise one or more sensors configured to generate an output based on an operating parameter of extrusion equipment 20 (e.g., viscosity, pressure, shear stress, and/or flow rate estimations from a motor current, voltage, rotational velocity, and/or other operating parameters of a motor included in extrusion equipment 20), and/or other sensors.

(25) Although sensors 16 are illustrated in FIG. 1 at a single location in apparatus 10, this is not intended to be limiting. Sensors 16 may comprise sensors disposed in a plurality of locations, such as for example, at various locations within (or in communication with nozzle pathway 30), within (or in communication with) transducer 14, and/or other locations.

(26) Controller 18 may be configured to control transducer 14 to oscillate based on the output signals from sensor 16. Controller 18 may be configured such that controlling transducer 14 to oscillate comprises controlling one or more of an oscillation direction, an oscillation amplitude, an oscillation frequency, and/or other oscillation parameters. In some implementations, controller 18 may be configured to control extrusion equipment 20 and/or other components of apparatus 10.

Controller 18 may be configured to control extrusion equipment 20 based on the output signals from sensors 16, and/or other information. Controller 18 may include one or more processors, electrical equipment (e.g., switches, a bus, wiring), valves, and/or other components that allow controller 18 to function as described herein. In some implementations, controller 18 may be configured to communicate with transducer 14, sensors 16, extraction equipment 20, and/or other components of apparatus 10 wirelessly and/or via wires.

(27) In some implementations, controlling transducer 14 to oscillate based on the output signals from sensor 16 may include determining whether the oscillations are effective and adjusting the oscillation direction, amplitude, frequency, and/or other oscillation parameters based on the effectiveness determination. The effectiveness determination may include determining one or more of the rheological parameters of the at least partially molten material within nozzle pathway 30 (e.g., viscosity, temperature, pressure, flow rate, molecular weight, density, etc.). The effectiveness determination may include determining whether one or more of the determined parameters has breached a parameter threshold. For example, controller 1 8 may determine that the at least partially molten material within nozzle pathway 30 is too viscous and control transducer 14 to increase the oscillation amplitude. The parameter thresholds may be determined at manufacture, entered and/or selected by a user interface that is part of extrusion equipment 20, and/or be determined in other ways.

(28) In some implementations, controller 18 may be configured to control transducer 14 to oscillate based on information entered and/or selected by users via a user interface that is part of extrusion equipment 20. For example, users may enter and/or select information related to an oscillation direction, an oscillation amplitude, an oscillation frequency, and/or other parameters via the user interface. In some implementations, users may enter and/or select information via the user interface related to a timing of the oscillation during the extrusion process. For example, users may enter and/or select information such that oscillation begins five minutes after the start of the extrusion process. Users may enter and/or select information such that oscillation is repeatedly cycled on for a given time period and off for a given time period during extrusion. In some implementations, controller 18 may be configured to control extrusion equipment 20 based the information entered and/or selected by users via the user interface that is part of extrusion equipment 20.

(29) The one or more processors that may be included in controller 1 8 may be configured to provide information processing capabilities in apparatus 10. The one or more processors may include one or more of a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and/or other mechanisms for electronically processing information. In some implementations, the one or more processors may be a single processing unit and/or may include a plurality of processing units. These processing units may be physically located within the same device (e.g., a computer that is part of extraction equipment 20), or the processors may represent processing functionality of a plurality of devices operating in coordination (e.g., transducer 14, controller 18, and extraction equipment 20). In some implementations, the processors may be configured to execute one or more computer program modules.

(30) Extrusion equipment 20 may include one or more components used during extrusion, additive manufacturing, 3D printing, and/or other manufacturing processes. Components used during extrusion may include, for example, a hopper, a feedthroat, a motor, a barrel, a screw, a breaker plate, a feed pipe, a die, a ram, a press, a heater, and/or other components. Components used during additive manufacturing and/or 3D printing may include, for example, a computer, a frame, a moveable head, a stepper motor, electronics, software, firmware, a heater, and/or other components. In some implementations, extrusion equipment 20 may be removably coupled with nozzle 12, transducer 14, controller 18, and/or other components. In some implementations, extrusion equipment 20 may be fixedly coupled with nozzle 1 2, transducer 14, controller 18, and/or other components.

(31) In some implementations, extrusion equipment 20 may include a user interface. The user interface may be configured to receive information from users of apparatus 10 and provide information to users of apparatus 1 0. As such, the user interface may include hardware and/or software to facilitate receiving information from the user and/or providing information to the user. The user interface may include, for example, one or more input devices such as a touchscreen, a touch pad, a keypad, a switch, an analog stick, a button, a dial, a microphone, and/or other hardware configured to receive information from a user. The user interface may include for example, one or more output devices such as a display, a touchscreen, speakers, and/or other hardware configured to provide information to a user. In some implementations, the user interface may be configured to present user configurable settings to the user. The user

configurable settings may be related to an oscillation direction, amplitude, and/or frequency of transducer 14, for example. The user interface may be configured to receive selections from the user of values for the user configurable settings.

(32) In some implementations, extrusion equipment 20 may include electronic storage. The electronic storage may comprise electronic storage media that electronically stores information. Such electronic storage media may include one or both of system storage that is provided integrally (i.e., substantially nonremovable) with extrusion equipment 20 or removable storage that is removably connectable to extrusion equipment 20 via, for example, a port (e.g., a USB port, a firewire port, etc.) or a drive (e.g., a disk drive, etc.). The electronic storage may include one or more of optically readable storage media (e.g., optical disks, etc.), magnetically readable storage media (e.g., magnetic tape, magnetic hard drive, floppy drive, etc.), electrical charge-based storage media (e.g., EEPROM, RAM, etc.), solid-state storage media (e.g., flash drive, etc.), and/or other electronically readable storage media. The electronic storage may include one or more virtual storage resources (e.g., cloud storage, a virtual private network, and/or other virtual storage resources). The electronic storage may store three dimensional models, software algorithms; information generated by sensors 16, extrusion programs, and/or other information that enables apparatus 10 to function as described herein.

(33) In some implementations, extrusion equipment 20 may include controller 18. In some implementations, extrusion equipment 20 may include a housing configured to house nozzle 12, transducer 14, sensor 16, controller 18, and/or other extrusion equipment. For example, nozzle 12, transducer 14, sensor 16, controller 18 and/or other components may be housed in a single housing and form at least a portion of a 3D printer used for additive manufacturing.

(34) FIG. 3 illustrates an extrusion method 300 for reducing swelling after extrusion. The operations of method 300 presented below are intended to be illustrative. In some implementations, method 300 may be accomplished with one or more additional operations not described, and/or without one or more of the operations discussed. Additionally, the order in which the operations of method 300 are respectively illustrated in FIG. 3 and described below is not intended to be limiting.

(35) In some implementations, method 300 may be implemented in one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and/or other mechanisms for electronically processing information). The one or more processing devices may include one or more devices executing some or all of the operations of method 300 in response to instructions stored electronically on an electronic storage medium. The one or more processing devices may include one or more devices configured through hardware, firmware, and/or software to be specifically designed for execution of one or more of the operations of method 300.

(36) At an operation 302, a nozzle pathway may be formed. The nozzle pathway may be formed to conduct an at least partially molten material in an extrusion direction from an input end to an output end. The nozzle pathway may have a first larger cross-sectional area at the input end and/or a second smaller cross-sectional area at the output end. Operation 302 may be performed by a nozzle that is the same as or similar to nozzle 12 (shown in FIG. 1 and described herein).

(37) At an operation 304, vibrational energy from one or more oscillating transducers may be received. The transducer may be coupled with the nozzle. In some implementations, the transducer may be located at or near the output end of the nozzle. The transducer may be configured to oscillate such that the vibrational energy from the oscillation is received by the nozzle. The received vibrational energy may cause changes in a temperature, a pressure, a volume, and/or other properties within the nozzle pathway. The changes in the

temperature, the pressure, the volume, and/or other properties within the nozzle pathway may induce changes in rheological parameters of the at least partially molten material. The changes in the temperature, the pressure, the volume, and/or other properties within the nozzle pathway may induce shear stress, for example, in the at least partially molten material. The rheological parameters of the at least partially molten material may include a viscosity of the at least partially molten material, and/or other rheological parameters. Operation 304 may be performed by a transducer and/or a nozzle that are the same as or similar to transducer 14 and/or nozzle 12 (shown in FIG. 1 and described herein).

(38) At an operation 306, output signals conveying information related to rheological parameters of the at least partially molten material within the nozzle pathway may be generated. Operation 306 may be performed by a one or more sensors that are the same as or similar to sensors 1 6 (shown in FIG. 1 and described herein).

(39) At an operation 308, the transducer may be controlled based on the output signals to reduce swelling of the at least partially molten material after extrusion. Controlling the transducer may comprise controlling an oscillation direction, an oscillation amplitude, an oscillation frequency, and/or other transducer parameters to cause changes in the rheological parameters of the at least partially molten material. The changes in the rheological parameters of the at least partially molten material may reduce swelling of the partially molten material after extrusion. Such swelling may comprise an increase in a cross-sectional area of the at least partially molten material to a third cross-sectional area that is larger than the second cross-sectional area of the nozzle pathway. In some

implementations, the direction of oscillation may be substantially parallel to the extrusion direction. In some implementations, the direction of oscillation may be substantially perpendicular to the extrusion direction. Operation 308 may be performed by a controller that is the same as or similar to controller 18 (shown in FIG. 1 and described herein). (40) In some implementations, the nozzle, the transducer, the sensors, the controller, and or other components may for at least a portion of a 3D printer used for additive manufacturing.

(41) Although the system(s) and/or method(s) of this disclosure have been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred implementations, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed implementations, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any implementation can be combined with one or more features of any other implementation.

Claims

What is claimed is:

1 . An extrusion apparatus, the extrusion apparatus comprising:

a nozzle forming a nozzle pathway to conduct an at least partially molten material in an extrusion direction from an input end to an output end, the nozzle pathway having a first larger cross-sectional area at the input end and a second smaller cross-sectional area at the output end; and a transducer coupled with the nozzle, the transducer configured to oscillate such that vibrational energy from the oscillation is received by the nozzle and causes changes in one or more of a temperature, a pressure, or a volume within the nozzle pathway,

wherein the changes in one or more of the temperature, the pressure, or the volume within the nozzle pathway induce changes in rheological parameters of the at least partially molten material, the rheological parameters including a viscosity of the at least partially molten material, and

wherein the changes in the rheological parameters of the at least partially molten material reduce swelling of the partially molten material after extrusion, such swelling comprising an increase in a cross- sectional area of the at least partially molten material to a third cross- sectional area that is larger than the second cross-sectional area of the nozzle pathway.

2. The apparatus of claim 1 , wherein the nozzle and the transducer are

configured such that changes in one or more of the temperature, the pressure, or the volume within the nozzle pathway induce shear stress in the at least partially molten material.

The apparatus of claim 1 , further comprising one or more sensors configured to generate output signals related to the rheological parameters of the at least partially molten material within the nozzle pathway.

The apparatus of claim 3, further comprising a controller configured to control the transducer to oscillate based on the output signals.

The apparatus of claim 4, wherein the controller is configured such that controlling the transducer to oscillate comprises controlling one or more of an oscillation direction, an oscillation amplitude, or an oscillation frequency.

The apparatus of claim 5, wherein the transducer is configured such that the direction of oscillation is substantially parallel to the extrusion direction.

The apparatus of claim 5, wherein the transducer is configured such that the direction of oscillation is substantially perpendicular to the extrusion direction.

8. The apparatus of claim 1 , wherein the transducer is located at or near the output end of the nozzle.

9. The apparatus of claim 1 , wherein the nozzle forms the nozzle pathway to conduct an at least partially molten polymer material in the extrusion direction from the input end to the output end.

10. The apparatus of claim 1 , wherein the nozzle and the transducer form at least a portion of a 3D printer used for additive manufacturing.

1 1 . An extrusion method, the extrusion method comprising:

forming a nozzle pathway with a nozzle to conduct an at least partially molten material in an extrusion direction from an input end to an output end, the nozzle pathway having a first larger cross-sectional area at the input end and a second smaller cross-sectional area at the output end; and

receiving vibrational energy from an oscillating transducer coupled with the nozzle, the vibrational energy from the oscillation being received by the nozzle and causing changes in one or more of a temperature, a pressure, or a volume within the nozzle pathway,

12. The method of claim 1 1 , wherein the changes in one or more of the

temperature, the pressure, or the volume within the nozzle pathway induce shear stress in the at least partially molten material.

13. The method of claim 1 1 , further comprising generating output signals

related to the rheological parameters of the at least partially molten material within the nozzle pathway.

14. The method of claim 13, further comprising controlling the transducer to oscillate based on the output signals.

15. The method of claim 14, wherein controlling the transducer to oscillate

comprises controlling one or more of an oscillation direction, an oscillation amplitude, or an oscillation frequency.

16. The method of claim 15, wherein the direction of oscillation is substantially parallel to the extrusion direction.

17. The method of claim 15, wherein the direction of oscillation is substantially perpendicular to the extrusion direction.

18. The method of claim 1 1 , further comprising locating the transducer at or near the output end of the nozzle.

19. The method of claim 1 1 , further comprising forming the nozzle pathway to conduct an at least partially molten polymer material in the extrusion direction from the input end to the output end.

The method of claim 1 1 , further comprising forming at least a portion of a 3D printer used for additive manufacturing with the nozzle and the transducer.