Optimisation procedure for additive manufacturing processes based on mask image projection to improve Z accuracy and resolution

Abstract

Mask image projection is an additive manufacturing (AM) technique used in photocurable materials which allows the simultaneous energy delivery in a whole area instead of a single spot. A common problem for this AM process is the uncontrolled penetration of light energy, which could cause a solidification of non - desired layers. In this paper , an optimization procedure is developed and presented in order to increase Z accuracy and resolution of printed parts through the control of the total accumulated dose and the photocuring conversion ratio of each spatial location of the manufacturing volu me. Consequently, the uncontrolled monomer - to - polymer conversion of down - facing surfaces could be reduced. A finite element strategy is used in the optimisation procedure to obtain a full discretization of the whole manufacturing domain. Furthermore, exper imental tests have been done to compare experimental results and numerical estimations. The results show that the use of the optimisation procedure increases the accuracy and resolution of printed parts along the manufacturing direction.Peer ReviewedPostprint (author's final draft

Enhancement of 3D-Printable Materials by Dual-Curing Procedures

“… Schematics of digital light processing (DLP) following bottom-up ( a ) and top-down ( b ) approaches, and ( c ) continuous liquid interface polymerization (CLIP). ( a , b ) have been reprinted from [ 7 ] with permission from Elsevier, and ( c ) has been reprinted from [ 5 ] with permission from the American Association for the Advancement of Science. …”

“…Schematics of all these abovementioned AM techniques are represented in Figures 1 and 2. [7] with permission from Elsevier, and (c) has been reprinted from [5] with permission from the American Association for the Advancement of Science. SL and DLP are based on the layer-by-layer solidification of liquid or liquidlike thermosetting formulations that react upon exposure to ultraviolet (UV) or visible light leading to a crosslinked material.…”

“…Schematics of all these abovementioned AM techniques are represented in Figures 1 and 2. [7] with permission from Elsevier, and (c) has been reprinted from [5] with permission from the American Association for the Advancement of Science. [7] with permission from Elsevier, and (c) has been reprinted from [5] with permission from the American Association for the Advancement of Science.…”

“…Nonuniform degree of cure throughout the printing direction leads to uneven and weak mechanical properties. High geometrical accuracy of the printed parts is often achieved at the expense of the completion of the curing process [ 7 ]. It is common practice to carry out a UV postcuring of the dry part after the 3D-printing stage in order to overcome these effects, but it is also acknowledged that UV light might be prevented from reaching the deepest layers of the material, therefore leading to regions with incomplete cure and nonuniform properties [ 8 ].…”

Preliminary studies on additive manufacturing of over 95% dense 3Y zirconia parts via digital imaging projection

“…Commercially available monomers are mono-, di-, tri-and tetra-functionalized monomers which, when applied, result in composite bodies with entangled linear polymers; however, if multifunctional monomers (more than one functional group which participate in the polymerization) are used, a cross-linked network of polymer chains are generated, which renders the cured body relatively stiffer and mechanically more resistant. Depending on the desired properties of the bodies (mechanical, thermal and degradation), hybrid mixtures with mono-and multifunctional monomers can be used [10][11][12].…”