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Design+ Feasibility of shell fusion technology in jewelry design

The debinding and sintering processes were regulated by A characteristic of the investment casting process is that,
a 1600 W electrical Furnace PID controller with four ramp due to the need for feeding, venting, and pressurization
curves and an insulation muffle, with sintering conditions channels, much of the molten material is not used in the
at 1130°C for 60 min. The sintering and debinding curves production of the part, and even if it is reused later, there is a
are presented in Figure 3. lot of energy and financial loss in the manufacturing process.

3. Results and discussion The SFT method is more automated and requires fewer
stages to produce the finished product. The mold cavity
Certain aspects of SFT can be compared with competitors’ is created immediately; curing procedures and refractory
processes, revealing significant distinctions between SFT linings are not required. Only debinding and liquid metal
and investment casting. melting are required to complete the shell’s construction.
The investment casting process uses CAD/CAM Without the need for manual operations, the two
systems to produce wax models, which speeds up the occurrences take place within the heat treatment furnace
modeling process but requires a lot of manual work to one after the other.
mount the pieces on the trees and place the feed channels. The pre-sintered shell/mold is then cooled, making it
For the mold cavity to eventually develop, the tree easier to break apart and remove the inside component.
must be coated with refractory ceramic suspension. The This operation can be completed quickly by hand without
assembly is placed in an oven to remove the wax and the need for specialized instruments, while strongly
thermally cure the plaster cast, creating a mold that is attached mold particles can be removed with a brush.
ready for liquid metal pouring. After the liquid metal is It is feasible to obtain a piece of silver for ornamental
poured, the tree solidifies, and its parts must be taken out purposes through the STF procedure, as presented in
of the feed channels before deburring and final finishing. Figure 4. To achieve better results in terms of the surface

Table 2. Parameters of shell manufacturing
Variable Fixed condition
Material temperature (°C) 30
Chamber temperature (°C) 75
Extrusion temperature (°C) 210
Layer thickness (mm) 0.2
Gap between fabrication lines (mm) 0.2
Tool diameter (mm) 0.6
Aided gas flow (m/s) 0.1
Ambient temperature (°C) 25
Relative humidity 0.3 Figure 3. Temperature curve of the furnace for material sintering used
in this study

Figure 2. Scheme of the shell fusion technology process Figure 4. A silver piece manufactured using shell fusion technology

Volume 2 Issue 1 (2025) 4 doi: 10.36922/dp.3869