High-Throughput Extrusion-Based Additive Manufacturing

Technology

The proposed technology consists of adding a pre-heater component and using both alternative forms of filament and upgraded designs of the extruder. The function of the pre-heater is to raise the temperature of the filament received from the extruder to a desired preheated temperature before it enters the liquefier. The pre-heater contains a transmitter capable of transmitting radiation or current that ensures the filament is uniformly heated. The extruder can be upgraded to contain a feature that improves filament engagement. The inside of the extruder contains a rotatable feed nut that meets the filament, producing a force capable of effectively driving the filament through the extruder. A device known as a die initially shapes the filament so that its form becomes complementary with the inside of the extruder. Thus, the filament becomes threaded and almost interacts with the extruder as two gears would. The die or the surface of the filament may be heated to aid this process. Parameters such as force applied to the feed nut of the extruder, power supplied to the pre-heater, and power supplied to the liquefier can be adjusted by use of a controller to produce desired preheat and melt temperatures as well as desired feed rates of the filament. Force and temperature measurements taken along the path of the filament through the printer are used to determine the extent of the adjustments to the parameters. Furthermore, the filament can be comprised of two different materials with varying conductivities so that upon melting the more conductive material remains less viscous, which may help advancement through the extruder.  

Problem Addressed

Current three-dimensional printing devices have multiple design limitations that impede high throughput, defined as the amount of material passing through the printer. These devices contain an extruder where material in the form of filament is put under pressure. Traditional extruder designs place insufficient pressure on the filament due to inadequate filament engagement area, hindering high throughput.  Furthermore, poor heat exchange between the filament and the liquefier requires extrusion to occur at lower speeds. If extrusion speed is increased, the filament does not fully melt, and solid fragments cause jams at the nozzle of the printer. Additionally, gantry designs, which refer to the frame structures that help determine printing location by supporting movement of the extruder-liquefier complex, cannot withstand high speed and acceleration. Attempts to increase gantry speed and acceleration require larger components, leading to increased mass and inertia, limiting overall performance. Moreover, the high pressure necessary for extrusion poses a challenge as the filament often has difficulty withstanding this pressure. Technology capable of overcoming these barriers by means of improved extruder designs and heating techniques is necessary to achieve higher throughput.  

Advantages

• Higher throughput 3D printing.  

• Reduces jamming because uniform heating is ensured. 

• Feedback mechanism using real-time temperature and force measurements optimizes conditions for high-throughput printing. 

Publications

Go, J., and A.J. Hart. "Fast Desktop-Scale Extrusion Additive Manufacturing." Additive Manufacturing 18 (2017): 276-284.