Application Cases

Experiment Name: Research on Post-Processing Algorithms for Five-Axis Electrohydrodynamic Conformal Jet Printing

Research Direction: The jet direction is not vertically downward but is "pulled" sideways by the lateral electric field. As the substrate's tilt angle increases, the jet's deflection angle also increases, leading to two printing issues: (1) The jet being pulled sideways causes inconsistency between the actual landing point and the nozzle's movement trajectory, affecting printing positioning accuracy; (2) The normal distance between the nozzle and substrate decreases while the voltage remains fixed, resulting in increased inter-electrode field strength and potential jet instability. These limitations restrict the application of electrohydrodynamic jet printing on curved surfaces. To mitigate the influence of curved surface electric fields and improve printing quality under such conditions, a five-axis electrohydrodynamic conformal jet printing process method is proposed.

Test Equipment: High-voltage amplifier, Function generator, Print head, Air valve, Industrial camera, PC industrial computer, etc.

Experimental Process:

Figure 1: Schematic diagram of five-axis electrohydrodynamic conformal jet printing

As shown in Figure 1, this approach integrates electrohydrodynamic jet printing technology with five-axis machining technology. The five-axis motion platform consists of three linear translation axes (XYZ) and two rotational axes. Through the two rotational axes, the nozzle can always remain coaxial with the normal vector of the curved substrate. Since the nozzle remains parallel to the electric field lines, the electric field does not affect the jet, thereby achieving improved printing quality.

Figure 2: Experimental platform for five-axis electrohydrodynamic conformal jet printing

An experimental platform for five-axis electrohydrodynamic conformal jet printing was established, as shown in Figure 2. This platform serves as a module for curved surface electronic integrated manufacturing equipment. The motion system primarily consists of three translation axes (XYZ) and two rotational axes (AC). The AC axes are mounted on the XY axes, and the curved substrate is fixed on the C-axis base. All motion axes are driven by servo motors. Each axis is equipped with a grating scale, and the motion control card (UMAC) achieves closed-loop control based on feedback from these scales. Under UMAC control, the five-axis platform enables vertical printing of the nozzle on the curved substrate, thereby avoiding the influence of curved surface electric fields. The platform also integrates various hardware components required for electrohydrodynamic jet printing: the high-voltage power supply's positive and negative electrodes are connected to the nozzle and substrate respectively; the flow pump is fixed on the Z-axis; the print head is mounted on the precision flow pump; a positioning camera is perpendicular to the substrate; and an observation camera is focused on the nozzle. As shown in the principle diagram (Figure 1), the platform is divided into four modules: motion, voltage, ink supply, and vision.

(1) The motion module comprises motion stages and a motion control card. The stages include three translation axes and two rotational axes, with the AC axes mounted on the XY axes, forming a dual-turntable five-axis structure. The programmable multi-axis controller (UMAC) is used, which provides developers with the PComm32 dynamic link library. By executing NC code files, the motion control card enables the multi-axis platform to achieve five-axis conformal printing.

(2) The voltage module consists of a function generator and a high-voltage amplifier. NI-VISA provides the USB communication protocol interface. The host computer program sends SCPI commands to the function generator to produce various waveforms (square, sine, triangular). The voltage signal is amplified 1000 times by the high-voltage amplifier and applied between the nozzle and substrate. Different electrical waveforms can generate different jet modes in electrohydrodynamic jet printing.

Experimental Results:

A five-axis electrohydrodynamic conformal jet printing method was proposed, and a corresponding platform was built. Since the axis coordinates of the dual-turntable five-axis platform are P(x, y, z, a, c), while the interpolated points obtained from preprocessing have coordinates P(x, y, z, i, j, k), a kinematic solution was established to define the mathematical relationship between these coordinate systems. Traditional five-axis machining uses a fixed feed rate F, which cannot reflect the actual printing speed in the workpiece coordinate system, leading to inconsistent line width. By applying piecewise cubic Hermite interpolation to constrain the position, velocity, and time of interpolation segments, the uniformity of printing speed was improved while ensuring smooth transitions in position, velocity, and acceleration between segments.

High-Voltage Amplifier Recommendation: ATA-7050

Figure: ATA-7050 High-Voltage Amplifier Specifications

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