Biomedical Engineering Reference
In-Depth Information
The excellent material
flow combined with an
optimally engineered
geometry of the part will
lead to a fiber-reinforced
female thread
Fiber flow can be
oriented around
complex shapes
Figure 3.30
X-ray image of composite flow molded bone plate (snake plate) with radiopaque wire markers showing
fiber flow around in-situ molded holes. Photo courtesy of Icotec AG.
methods, provided that the tools used are hard tipped,
because the material is quite abrasive and regular tools
may wear out relatively quickly. Diamond-tipped
tooling has been found to be the best option. Drilling,
milling, sawing, and grinding can be applied to carbon
PEEK materials to produce the finished product.
Computer numerically controlled machining in
general of PEEK materials is quite normal. It is
important to cool the machined part and air cooling is
recommended in preference to the use of a liquid
coolant. If a liquid coolant
must
be used, then it is
important that it does not affect the biocompatibility of
the PEEK material.
Some examples of machining conditions are
shown in
Table 3.4
:
Figure 3.31
Composite flow molded spinal fusion
devices made from ENDOLIGN. Photo courtesy of
Signus Medizintechnik GmbH.
Table 3.4
Examples of Machining Conditions
PEEK-OPTIMA
Reinforced
Process
Units
PEEK-OPTIMA
Sawing
Special Instructions
Clearance Angle
15 - 30
15 - 30
Rake Angle
0-5
10-15
Cutting Speed
m/min
500 - 800
200 - 300
Pitch
mm
3 - 5
3 - 5
Coolants
a
Compressed air
Compressed air
Drilling
Special Instructions
Milling is preferred in order to avoid zero speed that is present at the drill bit's centre
Clearance Angle
5 - 10
6
