Process Improvements in Fused Deposition of Ceramics (FDC): Progress Towards Structurally Sound Components

Abstract

Fused Deposition of Ceramics (FDC) is a Solid Freeform Fabrication (SFF) technique under development at Rutgers University. This technique is based on Fused Deposition Modeling (FDM)2, a commercially available SFF technology. Freeform fabrication of ceramic and metal parts is a means of significantly lowering the cost of currently expensive components. The feasibility of Fused Deposition of Ceramics (FDC) has been demonstrated in the recent past. Crucial to the viable fabrication of ceramic components is the elimination of defects in the parts. Apart from some of the usual traits of SFF techniques, some distinct features of FD Processing lead to defects in fabricated parts. The focus of this work is to study and improve the build procedure of FDM, thereby reducing the defects that are associated with FD processing. Predictable errors in the FDC/FDM components need to be consistently eliminated to increase the yield of fully dense, defect free, green parts. Changes in the manufacturing procedure and operation of FDC are shown to reduce these errors. Fully dense green components are further processed to obtain defect free fully dense sintered ceramic parts.

Structural quality of parts processed by fused deposition

“…However, the structural quality of these parts are limited by defects in the parts. The factors that limit defect‐free fabrication of structural ceramic or metal FDC and FDMet parts are either limitations in the current state of SFF technologies or limitations in the current state of commercial FDM systems[27, 30]. Most of the surface defects resulting in such parts are primarily due to current limitations in the state of the SFF technologies in general.…”

“…The size and occurrence of the sub‐perimeter void depends on the build conditions (road width, thickness, etc.) and the angle between the raster line and the perimeter curve[30]. Figures 6 and 10 show the presence of sub perimeter voids in the top surface and cross‐section of a polymer FDM part, respectively.…”

“…Therefore, the tool path in the build files has been mathematically altered, depending on build conditions such as road width, etc., to result in actual tool path motion which is closer to the sharp turn needed to get complete filling at these sites. This approach includes extending the corners of the raster segment turns, at the perimeter, closer to the perimeter[30] (see Figure 13). Such a change in the tool path in the build file results in the actual tool path motion which is a closer approximation of the sharp turn than the curved turn, described earlier.…”

“…These specific strategies result in defects which are reproducible in their location and nature. Since the defects are reproducible and not random in their occurrences, novel approaches and strategies have been introduced to improve the as fabricated part quality[28, 29, 30, 31, 32].…”