Biomedical Engineering Reference
In-Depth Information
Figure 2.11
Graphical representation of the differences between injection-molded and machined PEEK components.
Source: Invibio.
molding to avoid granular boundary parts in molded
parts. These boundary points may also represent
weak points in the components. If controlled
cooling over long time periods is practiced, then
compression-molded parts typically have higher
crystallinity and tensile strength than injection-
molded components. Although, in theory, milled
fibers or fillers could be compounded into PEEK for
compression molding, this is rarely practiced
because of the difficulty in ensuring a uniform fiber
distribution and therefore uniform properties in the
final component.
2.5.4 Film and Fiber Production
The use of implantable grade PEEK in fiber and
film form is a growing area of interest in medical
devices because of mechanical performance and
inherent purity. The industrial applications of PEEK
in these forms have been established for a number of
years. Thin sections of PEEK film are produced
by extruding polymer using a suitable die and
haul-off equipment, which controllably handles and
stores the film for secondary operations. PEEK film
can be produced in either crystalline or amorphous
forms by controlling the temperature of the casting
drums in the haul-off equipment. However, as
the thickness of the film increases, the production
Figure 2.12
PEEK polymer compression molding. The
figure shows a 20-ton compression molding press
(Rondol Kompress 20 T).
