Variable-Orifice-Size Nozzle for 3D Printing

This paper presents the general framework of the problem and the basis for the proposed idea, which lies in the design of a new extrusion nozzle for fused-deposition 3D printing, featuring a variable orifice that enables adaptive extrusion control to improve printing properties such as material efficiency, printing speed, and localized control of mechanical properties. The working principle is controlled compression, via a linear actuator, of a silicone sleeve installed inside a metal jacket. Constrained by the metal jacket, the diameter of the silicone sleeve’s through-hole decreases with increasing compression. Three experiments were carried out to verify the functionality of the new nozzle design. The first two explored how the size of the nozzle orifice changes with movement of the linear actuator and the resulting silicone sleeve compression and decompression. In the third experiment, three sample parts were printed to demonstrate how the variable-orifice-size nozzle extruded PLA. The orifice diameter was set to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.4</mn></mrow></semantics></math></inline-formula> mm for the first condition, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.7</mn></mrow></semantics></math></inline-formula> mm for the second condition, and, in the third experiment, the first two conditions were combined. The orifice diameter was set to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.4</mn></mrow></semantics></math></inline-formula> mm for the first half of the object and then abruptly reduced to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.7</mn></mrow></semantics></math></inline-formula> mm for the second half. The prototype variable-orifice-size nozzle system demonstrated the potential of adaptive extrusion control for improved material efficiencies, faster printing times, and localized control of mechanical properties. However, it also revealed hysteresis of the silicone sleeve, a problem that must be addressed.