Automotive Engineering - September 2022 - 26

A materials lesson in Civics
MATERIALS FEATURE
Exploded CAD illustration of the old
and new Civic liftgate modules.
Project leader Jill Fuel's manufacturing
engineering experience was vital in executing
the 2022 Civic Hatchback project on target.
seam-tracking system supplied by Montreal-based
Servo Robot.
The Civic design team prioritized crash safety, driving
dynamics, mass reduction and cost reduction/ease of
manufacture as the car's target attributes. The foundation
of these is a new generation of Honda's longstanding
'ACE' (Advanced Compatibility Engineering) body
structure that is 19% stiffer in torsion and 13% stiffer in
bending than the previous generation, with rear-suspension
mounting points that are 17% stiffer.
" Ease of manufacture and weight reduction really
complement one another, and were a big piece of our
early conversation, " Fuel said. In keeping with
Honda's overall materials strategy, the '22 Civic maintains
a steel-intensive materials mix in the body-inwhite,
with aluminum hood inner and outer panels
(stamped by Honda and the first AL hood on a Civic)
to reduce mass and meet pedestrian protection (pedpro)
targets. High-strength steel (HSS) content is up
versus the previous-gen vehicle, comprising 38% of
the body structure. " Our focus was to improve our IIHS
crash rating, which meant high-strength steel in the
engine compartment, side sills and door-ring stampings, "
she noted.
In her presentation at GDIS22, Fuel revealed the following
high-strength steel alloys content: Hot-rolled
tensile strength dual-phase, 19%; cold-rolled advanced
HSS, 16%; hot-rolled high strength with excellent formability,
9%; hot-rolled ultra-high-strength, 7%, and coldrolled
very high strength, 6%. The remainder of the steel
in the Civic hatchback's body structure is 29% galvannealed
commercial grade and 14% high-carbon alloy.
A sticky situation
Stiffer structures typically are more difficult to manufacture,
Fuel explained. " We increased our use of
26 September 2022
Typically seen on pricier models, the laser-brazed (shown in yellow) roof is a first
for Civic and required significant plant and process alterations.
structural adhesives and sealants on this project, but those materials
came with a list of criteria that were a struggle. How to weld through
it? How do you apply it to the same spot each time, at line rate? We
had to make the technology work in our existing facilities. The learning
curve with the adhesives took some time to master,. "
Honda's use of Dow sealers throughout the BIW now includes
high-performance structural adhesives in the underbody. The '22
Civic body uses 10 times as much adhesive as was used on the outgoing
model. It is applied in both continuous and stitch patterns, depending
on location and adjacent welds. In conjunction with spot
welds and new lateral steel reinforcements in the floor structure, the
adhesives significantly improve overall rigidity.
Fuel noted the challenges in adopting weld-through sealers in the
body shop. In some areas the sealant has to be applied before the
weld; this creates expulsion issues with the weld robot's electrode.
And the new super-high-performance adhesives have different flow
and set-up characteristics compared to the products with which
Honda Indiana was familiar, she said. " We had to develop new checkpoints
for the robots in this process, including new vision systems on
the line to ensure precise and repeatable location of the sealer with
the welds, " she explained.
The new Civic hatchback features an all-new rear liftgate construction
that reduces mass by 20% compared with the previous model's
all-steel liftgate. It uses a steel inner stamping surrounded by durable
impact-resistant, resin-based inner and outer skins. The new " hatch "
also is perhaps the 2022 car's most recognizable change. The liftgate
is shipped to Greensburg as a complete assembly from a supplier.
AUTOMOTIVE ENGINEERING
CLOCKWISE FROM TOP LEFT: LINDSAY BROOKE; HONDA; HONDA
Automotive Engineering - September 2022

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