Boat Construction
Using
the
Injection
Molding
Process
The
construction
methods
used
for
cruising
yachts
have
been
evolving
over
time
and
Dufour
Yachts
has
always
kept
abreast
of
any
new
technologies
What
is
meant
by
injection
molding
?
This
particularly
innovative
technique
enables
GRP
assemblies
to
be
built,
no
longer
by
creating
several
layers
of
cloth
by
hand,
but
by
directly
injecting
the
resin
into
a
mold
using
a
system
of
pumps,
after
first
laying
up
the
cloth.
The
glass
reinforcements
and
PVC
foam
items
are
placed
on
the
punch
(pre-designed
areas
in
the
mold),
then
the
two
molds
are
stacked
and
centered
with
pins.
The
two
halves
are
drawn
together
mechanically
to
form
a
tight
joint
around
the
seals
and
a
vacuum
is
then
created
within
the
mold.
The
resin
is
then
injected
at
two
points
and
distributed
via
a
manifold
system.
The
Bi-axial
glass
cloth
then
draws
the
resin
into
the
void
between
the
molds.
A
first
prototype
is
made
without
gelcoat;
this
translucent
part
enables
Dufour
to
insure
that
we
have
a
controlled
and
perfect
diffusion
of
the
resin
throughout
the
entire
volume
of
the
deck.
The
consistency
of
the
following
decks
is
controlled
by
ultrasonic
probing,
checking
the
thickness
and
density
of
the
material.
The
use
of
this
process,
by
Dufour
for
the
deck,
is
accompanied
by
the
employment
of
high
technology
materials:
- Bi-axial EBX glass cloth that gives better rigidity
- High-density waterproof PVC foam, for the sandwich core
- Dicyclopentatdien (DCPD) resin with low styrene content, for optimum impregnation of the fibers and better surface aspect
Initially
used
to
manufacture
small
sub-assemblies
from
1997
onwards,
this
technique
has
now
been
used
by
Dufour
Yachts
for
2
years
to
produce
entire
upper
deck
assemblies.
Today
only
Dufour
Yachts
is
able
to
produce
such
large
yacht
structures
using
this
injection
molding
technique.
After
being
one
of
the
first
boatyards
to
apply
the
"vacuum
bagged
sandwich"
construction
process,
our
development
and
production
teams
have
now
acquired
a
mastery
of
injection
molding
technology,
which
demonstrates
their
great
capacity
for
innovation.
<<<
The
Injection
mold
What are the advantages of using this manufacturing process ?
Injection
technology
reduces
exposure
to
the
atmosphere
of
waste
products,
providing
better
compliance
with
environmental
standards
and
working
conditions.
The
technique
enables
the
production
of
highly
accurate
components,
within
set
tolerances,
which
eases
the
final
assembly
phase
with
less
of a
requirement
for
adjustments.
Production
is
more
homogeneous
and
the
arrangement
of
the
cloth
and
reinforcements
is
done
more
rigorously
and
the
variation
in
the
quantity
of
resin
is
negligible.
The
process
improves
the
quality
and
the
reliability
of
the
yachts
made
this
way.
The
weight
benefits
obtained
improve
boat
stiffness
and
lower
the
center
of
gravity,
with
better
structural
strength,
thanks
to a
better
saturation
of
the
glass
by
the
resin.
Furthermore,
less
tooling
is
required
for
a
given
level
of
high
volume
production.
The
absence
of
an
inner
deckhead
molding
and
it's
bonding,
the
strict
control
of
the
quantity
of
resin
and
the
material
used
allows
for
a
weight
saving
of
about
30%
compared
with
a
traditional
deck
-
just
where
its
effect
is
most
beneficial
-
better
stiffness,
lower
center
of
gravity
and
better
sea
handling
characteristics.
With
both
sides
being
coated
with
gelcoat
the
interior
finish
is
excellent
without
having
to
resort
to a
lining,
and
without
any
appearance
of
raw
laminate.
Injection
is
used
in
the
manufacture
of
yacht
decks
up
to
40
feet
in
length.
Beyond
this
an
infusion
technique
is
used,
which
is
also
state-of-the-art.
Another
article
will
later
be
devoted
to
this
technique.
_______________________________________________________________________
This
information
was
published
in
the
December
2002
issue
of
issue
of
Dufour
Mag
and
edited
by
Dufour
USA
for
publication
on
the
website.
This
process
is
used
by
Dufour
on
the
Dufour
34
and
40
as
well
as
the
Gib'Sea
37
and
41
decks.
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