Rapid Form Copying and Rapid Mould-Making Systems for Biodevices - Advanced Design and Manufacturing Technologies for Biomedical Devices - page 202

s hardness and expected life of the rapid tool or
cavity obtained, the rapid tooling processes can also be divided in some more groups
commented below:

Depending also on the material '

Soft tooling . Makes reference to silicone moulds obtained by rapid form copying
processes, which usually allow for the manufacture of short series of 25-50 poly-
meric parts by casting or vacuum casting, as the mould material progressively dete-
riorates due to thermal shock when the polymers are casted or thermally cured.

Bridge tooling . Makes reference to harder moulds obtained usually by rapid form
copying using low-melting-point alloys or pre-polymers with metallic or ceramic
micro-/nanocharges used for increasing hardness, mechanical resistance and cavity
service life. Normally short-medium series of 100-1,000 parts can be obtained by
conventional injection moulding, once the cavities are arranged as a prototype
mould. As the mould material has usually a polymeric matrix, temperature cycles
produce continuous relevant mechanical deformations and stresses and the mould
deteriorates rapidly.

Hard tooling . Makes reference to rapid moulds obtained in metals aiming to
provide the most possible similar results to those from fi nal production injection
moulding using steel moulds. Normally the cavities are obtained by easy
machinable metals (aluminium alloys, brass, etc.) by high-speed CNC machin-
ing or by additive manufacturing technologies capable of working with metals
(normally starting from metallic power), such as selective laser sintering, selec-
tive laser melting, laser cusing and laser cutting, among others. Much larger
series (in many cases for substitution of fi nal production) even up to 100.000-
500.000 parts can be obtained.
The aforementioned processes provide a step-by-step validation, increasing the
level of detail of fi nal prototypes and their resemblance to mass produced parts,
helping to detect and correct possible defects before investing in fi nal steel moulds
for mass production. Additional information on these processes and on the different
tolerances, expected life of components and typical industrial applications can be
found in the references (Lorenzo-Yustos 2008 ).
The next section provides an overview of applications of rapid form copying and
rapid tooling for the biomedical fi eld, before focusing on more specifi c case studies
linked to the development of biodevices for in vitro and in vivo trials using adequate
biomaterials.

11.2 Benefi ts from Using Rapid Form Copying

and Rapid Tooling for the Biomedical Field

Rapid prototyping by means of additive manufacturing was already highlighted in
Chap. 10 as a powerful set of technologies capable of enormously promoting the
optimisation of cost and schedules in conventional product development processes.