R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

178 Medical modelling
Case study 2
The scan for the second case was carried out as before. In the interests of
comparison, a mould was manufactured using stereolithography (SLA ® )
(3D Systems Inc., 126081 Avenue Hall, Valencia, CA 91355, USA). SL
materials and process time are more expensive than LOM TM ; therefore, to
reduce cost, the data was reduced to a thin shell shown in Fig. 6.48. As the
glass transition temperature of SL materials may be exceeded during
vacuum forming, the shell was fi lled with plaster as shown in Fig. 6.49. This
prevented the SL shell from distorting under the load and heat encountered
in vacuum forming.
Experimental moulds
The ThermoJet ® (3D Systems Inc.) RP process prints three-dimensional
models using a wax material in a layered manner. The layers are very thin,
leading to models with excellent surface fi nish. However, the low melting
6.48 Shelled solid computer model.