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Dream was created to
make advanced composite technology
more accessible to customers. Advanced composites, when designed
properly and for a specific need, can far surpass the strength,
stiffness and lightweight characteristics of today's metals.
Their CTE's can be substantially lower (and in specific cases
negative CTE's are possible) than common metals. Click
here to see a comparison showing why advanced composites
are so beneficial compared to metals. |
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Dream's specializes in the use of advanced composites,
mostly carbon fiber, in combination with sandwich core technology.
To learn more about the enormous benefits of sandwich core, click here. |
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Dream was also
created to push past boundaries both in telescope & accessory
designs. An attempt is made at every turn to use composites instead
of metals, both for thermal stability and light-weighting. |
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Thermal characteristics
normally far outway other criteria in a telescope system. Things
like rapid mirror cool down, light
baffling, a rigid OTA struture and precision movements are all
needed however for the utmost performance and the highest throughput. |
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Many companies
use carbon fiber products that have a clear, glossy finish. This
leaves the part with one of two commonly used weave patterns,
2x2 twill or plainweave. Unfortunately this also leaves the part
charcoal black. This color exterior will heat up the interior
of the OTA and therefore the optics, when exposed to Sunlight.
It will take that much longer for the optics to cool down. Dream
has tested black surfaced materials in moderate temperatures,
70F, and found that they easily reach 160+ degrees in Sunlight!
This is a potential problem for all composite parts, not just
opto-mechanical products. Please read below for an explanation. |
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Using bright white (some
silver paints work too) greatly reduce the amount of heat buildup
and therefore promotes the quickest equilibrium times. Excess
heat in advanced composites can also facilatate a breakdown of
the laminate, especially with room temperature cured resins.
Layers of reinforcement (fiberglass, carbon fiber, etc.) will
start to delaminate from each other, for example, if a temperature
threshold is exceeded. This can be prevented by using high temperature
epoxy that allows cooking the advanced
composite parts. This raises their properties so that they do
not have delamination issues, if designed and produced correctly.
Dream is currently working with high temperature epoxy (~$110/gallon)
that can be cured at up to 350F, if the application requires
it. |
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In sandwich core use temperatures are again a factor
that must be considered. Some foams and honeycombs ($100-$300
per 4'x8' sheet) can only withstand temperatures of 230-250F.
If the product will see temperatures above this, specialized
cores like Nomex honeycombs or Rohacell
foams can be used ($250-$700+ per 4'x8' sheet). |
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To learn more about the background of Dream and elevated
temperature epoxy, click here. |
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Epoxy resins are
UV sensitive, as are most resin systems. They will degrade if
directly exposed to UV rays. Composites should always be protected
with a UV barrier layer(s) to help increase the longevity of
the product. |
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To learn more about advanced
composites, click here. |
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