A novel projection based electro-stereolithography (PES) process for production of 3D polymer-particle composite objects

Abstract

Purpose Polymer-particle composites, which have demonstrated wide applications ranging from energy harvesting and storage, biomedical applications, electronics and environmental sensing to aerospace applications, have been investigated for decades. However, fabricating polymer-particle composites with controlled distribution of particles in polymer continues to be a fundamental challenge. As to date, a few additive manufacturing (AM) technologies can fabricate composites, however, with a limited choice of materials or limited dispersion control. Against this background, this research investigated a hybrid polymer-particle composite manufacturing process, projection electro-stereolithography (PES) process, which integrates electrostatic deposition and projection based stereolithography (SL) technologies. Design/methodology/approach In PES process, a photoconductive film collects charged particles in the regions illuminated by light. Then, collected particles are transferred from the film to a polymer layer with defined patterns. Lastly, a digital mask is used to pattern the light irradiation of the digital micromirror device chip, selectively curing the photopolymer liquid resin and particles of that layer. By transferring particles from the photoconductive film to the photopolymer in a projection-based SL system, multi-material composites with locally controlled dispersions could be produced. A proof-of-concept PES testbed was developed. Various test cases have been performed to verify the feasibility and effectiveness of the developed approach. Findings Challenges in this novel AM process, including process design, particle patterning and transferring, are addressed in this paper. It is found that particles can be transferred to a layer of partially cured resin completely and accurately, by using the stamping approach. The transferring rate is related to stamping force and degree of conversion of the recipient layer. The developed hybrid process can fabricate polymer-particle composites with arbitrary dispersion pattern, unlimited printable height and complicated geometries. Originality/value Although an electrostatic deposition process has been investigated as a 3D printing technology for many years, it is the first attempt to integrate it with projection SL for fabricating multi-material polymer composite components. The novel hybrid process offers unique benefits including local dispersion control, arbitrary filling patterns, wide range of materials, unlimited printable height and arbitrary complicated geometries.

3D‐Printed Anisotropic Polymer Materials for Functional Applications

“…Extensive research efforts have been devoted to developing VP‐based multi‐material printing techniques, which can be divided into the following methods: material combination via multi‐vat system, [ 114,126 ] spatially controlled material compositions via chemoselective wavelength, [ 116 ] filler combination via additional feeder setup, [ 127 ] dynamic fluidic control, [ 115 ] etc. Based on these methods, the reported multi‐materials reveal anisotropy in terms of property variation, such as swelling and mechanical anisotropies, along the build direction, and are mainly employed in soft actuators, metamaterials, and bioinspired synthetic heterogeneous materials.…”

“…proposed a projection‐based electro‐SLA process. [ 127 ] Particles could be transferred from a photoconductive film to a polymer layer into the regions illuminated by light before the liquid resin was cured. By using this stamping approach, multi‐materials with defined patterns could be obtained, which had unique advantages such as local dispersion control and arbitrary complicated geometries.…”

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

“…1. Compared to free surface process, the constrained surface process has several advantages including less material waste, higher resolution, and faster speed, and is being used increasingly recently [2][3][4][5][6][7][8][9]. Despite the advantages, the separation of a newly cured layer from the constrained surface is a historical technical barrier and still greatly limits the printable size, process reliability, and print speed [10].…”

Spring Assisting Mechanism for Enhancing the Separation Performance of Digital Light Process 3D Printers

“…Third, the spring assisting mechanism has a lower cost than other proposed mechanisms [11]- [14] because the cost of adding a vibrating, fluid, or x-axis displacement mechanism far exceeds the manufacturing and energy consumption costs required for a spring mechanism. Moreover, the stability of the system during use and the cost of subsequent maintenance highlight the value of the spring assisting mechanism over other mechanisms.…”

“…Pan et al proposed a two-step workflow of separation [ Fig. 1(c)], where the sliding action is performed horizontally and the pulling-up action is performed vertically [11], [12]. Wang et al proposed a pumping mechanism in which an empty area is prepared under the constrained surface to allow water or air to be injected.…”