Automotive Engineering - March 2021 - 14

Metal 3D printed bracket for BMW's Rolls-Royce Ghost.

BMW additivemanufacturing
line for non-metal
components.
operation at production sites around
the world. Access to the latest technologies is gained through long-standing partnerships with leading manufacturers and universities, and by successfully scouting for industry newcomers,
according to the company.
" Our goal is to industrialize 3D printing methods more and more for automotive production and to implement
new automation concepts in the process chain, " said Daniel Schäfer, senior
VP for Production Integration and Pilot
Plant for the BMW Group. " This will allow us to streamline component manufacturing for series production and
speed up development. " He said his
group is collaborating with vehicle development, component production,
purchasing and the supplier network, as
well as other areas of the company " to
systematically integrate the technology
and utilize it effectively. "
14 March 2021

A stated purpose of the Additive
Manufacturing Campus is to automate
process chains that typically required a
large degree of manual labor, to make
3D printing more economical and viable
for use on an industrial scale over the
longer term. But research projects also
are a backbone of BMW's efforts to expand additive manufacturing for automotive mass production. It is collaborating with various research efforts to
establish Germany as an additive-manufacturing pioneer.

Merging with the EV ecosystem

In late 2020, Porsche announced that it
used additive manufacturing to produce
its first complete housing for an electric
vehicle (EV) traction motor/integral
transmission drive unit. The case was
3D-printed via a laser-fusion process
and met all of the company's quality
and stress metrics.

" This proves that additive manufacturing, with all its advantages, is also
suitable for larger and highly-stressed
components in electric sportscars, " said
Falk Heilfort, project manager in the
Powertrain Advance Development department at the Porsche Development
Centre in Weissach, Germany. Porsche
added that the 3D-printing process for
the prototype part also allowed engineers to consolidate several development phases.
The 3D-printed drive-unit housing is
approximately 10% lighter compared
with a conventional cast-aluminum part.
The process also enables the stiffness in
highly stressed areas to be doubled.
Multiple parts and their functions are
consolidated, resulting in reduced assembly time and higher quality.
Porsche's 3D-printed EV structure
integrates the drive motor and a 2-speed
transmission. It is designed for application on the front axle of a sportscar. A
high-purity metal powder was employed
for the laser metal fusion (LMF) process
that uses a laser to heat and melt the
metal to the specified part contours.
The weight of the housing parts was
reduced by approximately 40% due to
the integration of functions and optimization of part topology, Heilfort
claimed, and helped deliver the overall
weight savings of nearly 10%. But stiffness was simultaneously increased; although the housing has a continuous
wall thickness of 1.5 mm (0.06 in), the
stiffness between the e-motor and
gearbox was doubled due to the lattice
structures of the 3D-printed design.
Meanwhile, the honeycomb structure
also reduces oscillations of the housing
walls, improving the overall acoustics of
the drive unit.
Integration of parts made the drive
unit more compact, " significantly improved the drive package " and reduced
the assembly by about 40 work steps
- equivalent to reduction of production
time of approximately 20 minutes. And
overall performance and cooling is enhanced by integration of the gearbox
heat exchanger and the resulting optimized heat transmission.
Bill Visnic

AUTOMOTIVE ENGINEERING

BOTH IMAGES: BMW

TECHNOLOGY REPORT

Automotive Engineering - March 2021

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