Shift Magazine - March 2021 - S26

Porsche 3D-printed a
prototype electricdrive housing
for small-series
production.

last mile
3D-PRINTING A PORSCHE:
MAKING CONCEPTS MATTER

BY JACK KEEBLER

anufacturing's digital data, fed
into a special 3D laser printer,
literally can turn an engineering concept into a large, fully
stressed metal part.
Porsche is taking advantage of 3D printing, or " additive manufacturing, " to quickly
plug electric vehicle components into its
vehicle-development programs. The automaker is working to make not only its vehicles, but also its build processes, agile and
fast. But as usual, quicker comes at a cost.
Engineers at Porsche's Weissach
Development Center in Germany
recently built a light-alloy, electric-drive
housing using a laser-fusion 3D-printing
process. This technology holds promise
for Porsche's special and small-series
production and motorsports efforts.
" This proves that additive manufacturing, with all of its advantages, is also
suitable for larger and heavily stressed
components in electric sports cars, " Falk
Heilfort, the project manager, said in a
statement.
But importantly, this type of " printer "
costs between $100,000 and $5 million.
So, unless one of the growing number
of contract-printer vendors is used, the
return on investment will depend on
throughput. Parts can be printed in aluminum, steel, nickel, copper, bronze, titanium, silver or even alloy mixes.
" It's called laser metal powder-bed
fusion, " explained Terry Wohlers, president of consulting firm Wohlers Associates
26

shift * march 2021

in Fort Collins, Colo. " And in relatively low
quantities, it can be an effective way to
produce parts. But it's not Jeep doing the
Grand Cherokee in the hundreds of thousands. You'd be casting and machining
those metal parts. "

LIGHTENING UP

Ideas move from a CATIA digital sketch
to a more highly detailed engineering
drawing that can be loaded directly into
the printer for production, eliminating the
normal toolmaking step.
Thermal- and load-analysis programs
optimize the design for quietness, mass
and strength. The component also will be
modeled so that it uses fewer parts and
fasteners and is smaller and less expensive than a traditional part that is cast,
milled, pressed, drilled or turned.
In Porsche's case, the housing is 40
percent lighter than a cast part and, once
integrated, provides a 10 percent lighter
motor-gearbox unit.
" Our goal was to develop an electric
drive with the potential for additive manufacturing, at the same time
integrating as many functions and parts as possible in the drive housing, saving weight
and optimizing the
structure, " Heilfort
said.
The engine-gearbox
unit is produced via
the additive laser
fusion process.

The design data, analyzed by engineers
and even artificial intelligence, is converted into a job file. Then it is fed to the
five-axis head in the printer.

LAYERED APPROACH

The digital model is broken into data
slices. The head's nozzle sprays out metal
powder in layers 0.02 mm to 0.1 mm thick.
The nozzle is paired with a laser that heats
that layer of alloy powder, melting its particles together, under a cloud of argon shield
gas. And the process repeats. The part's
walls are built up with successive layers
also fused together by the laser's blast.
With the earlier printer, the housing
required several days and two processes,
but Porsche's experts have upgraded
hardware and say they can now do the
housing as a single unit in one process.
Given that, they estimate print time could
be slashed by 90 percent. So, no matter
how you slice it, that is
much faster. n

Shift Magazine - March 2021

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