CPT International 01/2015

Classical Porsche cars are popular but many special parts like cylinder heads
are no longer available (Photos: Por sche, Voxeljet)
Author: Stefanie Riker, voxeljet AG, Friedberg
Reconstructing cylinder heads for
Porsche legends
Anyone who owns a legendary Porsche
550 Spider, 904 or 356 Carrera can
count himself lucky. Unfortunately special
parts like cylinder heads are no longer
available. In the event of damage,
the only remedy is through customized
parts reconstruction or reverse engineering,
and 3-D printing turned out
to be the cheapest way.
Reconstructing complex components
(Figures 1-4) is a challenge for every design
engineer, because drawings are not
available in most cases. In this particular
case, the reconstruction of a Carrera
cylinder head made of aluminum started
with measuring and scanning of the
defective head.
Valve guides, seat rings, camshaft
bearing, intake and exhaust ducts, cylinder
head screws etc. had to be set up
as 3-D base bodies in a meticulous detailed
process. The next step was the
transfer to superordinate functional
models and the adding of design features
from casting technology like site
measuring, bevels, and fillets.
Affordable 3-D cores
After the geometric reconstruction
made by the company CAD Support
from Mössingen, Germany, the production
of the sand cores was the next item
on the agenda. The project implementation
with conventional cores based
on core-making tools was impossible
for cost reasons. The only solution was
creating the cores in a 3-D printer.
The order for printing the entire core
package with eleven cores in total went
to the voxeljet service center in Friedberg,
Germany, which has many years
of experience in project of this kind.
Thanks to the excellent printing quality
of the voxeljet printer, it was also possible
to outline the thin-walled cooling
8 Casting Plant & Technology 1/2015