R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

6.83 The support structure in 3D Lightyear TM .
Case studies 229
SLA-250 in Waterclear TM example The STL framework design was prepared
using 3D Lightyear TM (3D Systems Inc.) with a ‘fi ne point’ support
structure (Fig. 6.83). The framework was oriented with the fi tting surfaces
facing upwards to avoid the rough fi nish created by the support structures
affecting the fi t.
Two build styles were compared: standard 0.1000 mm thick layers and
high-resolution 0.0625 mm layers. Once completed, the patterns were carefully
removed from the machine platform and cleaned in isopropanol. They
were then post-cured in UV light to ensure full polymerisation. The other
patterns were produced according to the supplier specifi cations.
Pattern comparison
Of the four RP processes compared in this study, the SL processes provided
the most suitable patterns. The SL patterns were accurate, robust and had
an acceptable surface fi nish, but did require relatively lengthy cleaning and
fi nishing when removing support structures. The Thermojet ® build preparation
was simpler and faster than SL and both the ThermoJet ® and
Solidscape ® processes produced accurate patterns with a good surface fi nish
that required minimal fi nishing. These wax patterns were, however,
extremely fragile and could not be cast. The Perfactory ® -produced pattern