High-Sensitivity Interlayer Force Measurement and Multi-Layer Smoothing Control for 3D Printing on Uneven Surfaces (2025-07)¶

In 3D printing using the material extrusion method, a deposition motion that maintains a constant contact state is important to prevent failures. In this research, a 3D printing system by controlling the nozzle feed rate was implemented to realize adaptive deposition motion for non-planar surfaces. In addition, a device for measuring nozzle contact force between nozzle and surface using highly sensitive load cells is developed to enable the measurement of reaction force during deposition motion. In this method, the nozzle velocity is slowed down at points where the gap between the nozzle and the substrate is large, thereby increasing the flow rate of deposited material and smoothing the unevenness. This study derives the relationship between nozzle feed rate and material deposition height using the equation of continuity. By adjusting the nozzle feed rate, the system enables printing on uneven or inclined surfaces without altering the nozzle trajectory. To verify the smoothing method using nozzle velocity control, experiments were conducted on two geometry patterns to confirm the effect of smoothing by nozzle velocity control and the response of nozzle reaction force during deposition motion. Additionally, a multi-layer surface levelling by adjusting nozzle velocity was introduced to suppress the amount of smoothing in a single layer in order to suppress changes in cross-sectional shape due to increased flow rate. This study confirms that controlling the nozzle velocity improves surface smoothness and maintains consistent reaction forces, enhancing 3D printing accuracy on uneven surfaces.