1. Q: Are all carbon fiber parts brittle and
therefore extremely fragile?
....A: This is a common misconception.
Dream's properly made
carbon fiber parts are not fragile. Please see the videos on this page
as a vivid illustration of just how rugged Dream's advanced composite
parts are. Also keep in mind that Dream's composites are inherently
resistent to moisture/humidity, are non-corrosive, have a low
CTE, low thermal fatigue and are quite chemically resistent.
Because we cook each part in one of our ovens, the parts are
also stable at higher temperatures.
2. Q: Do all carbon fiber parts vary in mechanical
performance from part to part, making them impossible to use
in high-performance opto-mechanical systems?
....A: Most of the time this comment
is coming from companies or individuals that have little to no
knowledge of advanced composites. Or they have tried Dream started
as an advanced
composites company solely for the purpose of making structures
for opto-mechanical systems, which require high-stiffness, not
strength, and low CTE. Dream isn't a standard "composites
shop" that makes fiberglass boats or car bumpers. Such shops
lack an understanding of the extremely tight tolerances that
are required for opto-mechanical systems. We are the only company
in the world that has a deep understanding of optics and a deep
understanding of composites. Dream understsands composite materials
& methods as they relate to stiffness and CTE. We have tight
process controls, like our +/-1°F largest composites oven.
Bringing all of this together
has allowed us to focus on methods that are highly consistent
from part to part.
3. Q: Do all carbon fiber parts vary in Coefficient
of Thermal Expansion (CTE) from part to part, making them impossible
to use in high-performance opto-mechanical systems?
....A: As stated above Dream has
always had optical systems in mind for the composties. We are
not a general composites company that is trying to shoehorn our
composites into precision optical systems. Dream was formed specifically
for the opto-mechanical industry. We can produce a part today,
then again two years from now with extreme consistency in the
part, both mechanical performance (question 2. above) and CTE
(question 4. below). They typically coincide with each other
(mechanical and thermal), although mechanical properties and
thermal properties are two completely different attributes of
4. Q: Do all composite parts have resin-rich
areas that will have a wildly different CTE than other areas,
therefore causing the part to distort?
....A: From day one Dream has
always; paid especially close attention to fiber orientation
& resin content, used high-temperature epoxy that is specifically
engineered for an optimal match to our mirrors, used vacuum bagging
and high temperature baking of the parts to provide the utmost
in consistency and part performance. Wildly varying performance
is common in wet layup parts that do not use vacuum bagging.
Overwrapping the parts with weak plastic, similar to Saran Wrap,
will have almost no force on the part and therefore are not consolidating
the layers of CF. Part thickness can easily be double when full
vacuum bagging is not used. If carbon fiber parts that you have
received from others make cracking sounds when you squeeze them
tightly, they are inferior parts. Those are void areas collapsing
and are a red flag that the piece is not a high performance part.
Full vacuum is applying roughly one ton of force on the part
per square foot. A part with six square feet of surface area
has roughly six tons of force applied across the part. Unlike
a press, that inherently will have "hot spots" (higher
pressure and subsequent lower pressures), properly executed vacuum
bagging will produce the same pressure across the entire part,
regardless of it's shape. It is technically impossible for Dream's
advanced composite parts to have wildly different CTE, because
of our extensive exerpience, focus on making consistent parts
and proven methods that we use.
Contact Dream today to discuss your
project with our experts.