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Insaco's first business in 1947 was fabricating
sapphire parts (i.e. phonograph needles). This work was all
accomplished through a diamond grinding process, which is extremely
accurate, though painstaking, and the only practical method to
machine complex shapes using this crystal material. Once we
established our expertise working with extremely hard, yet fragile
materials we began accepting work fabricating other extremely hard
technical ceramic materials such as alumina, zirconia, silicon
carbide, among others, as well as glass that included quartz and
fused silica. Insaco does not machine metals or plastics simply
because they are too soft to be machined effectively with our fine
diamond wheels. Please visit our
materials webpage
for a list of materials we have worked on in the past with links to
specific material properties.
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Insaco welcomes small lot or even single piece
orders as well as production series. Obviously the single piece
prices will be higher because set-up and handling costs can’t be
distributed over a larger base. Small quantities may also preclude use
of larger, more automated machine tools. But big orders usually start
with small orders, and small orders are always welcome.
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Most ceramics can be formed (cast, molded,
pressed) in a soft state with features in place. This is not unlike
forming a red brick as used in building a house but before it gets
kiln fired. Once fired, the ceramic shrinks considerably which creates distortion and allows
tolerances typically of only 2% (or .003” whichever larger). If these tolerances
are acceptable for the end use, like a brick for your house, then the cost can be low. If
tighter tolerance is required, then additional work like diamond
grinding is required. So, careful consideration of tolerances for your
application may avoid the need for and expense of post-fire grinding.
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Insaco does not produce or sell ceramic
materials themselves. For this reason, we can offer advice without
bias. Alumina is the most common technical ceramic and hence most
readily available and usually lowest cost. Properties of alumina are
exceptional in many ways when compared to conventional materials
like steel. If the use conditions exceed these properties,
other technical ceramics such as
Silicon Carbide
or Zirconia may be better choices even though less
available or more difficult to fabricate. Please see our
materials webpage for more
information on the materials we frequently machine.
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Sapphire is an anisotropic, rhombohedral
crystal, and therefore non-uniformly dimensioned. Anisotropic materials exhibit some
properties such as thermal expansion uniquely to orientation. For most applications
this is unimportant, however should be considered. Sapphire is “birefringent”
which is a refractive feature that offsets wave transmission up to 0.8% at right angles
to the optic axis. Birefringence is eliminated along the optic or C-axis. For certain
applications, C-axis sapphire should therefore be specified to avoid birefringence
concerns.
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No. Sapphire cannot be molded like some other materials.
Industrial sapphire is created by melting aluminum oxide
(Al2O3) at 2040°C and then encouraging crystal growth
with a seed and careful control of the environment. Growers have developed
several unique methods for growth, with varying levels of resultant quality, size,
and cost. The EFG or Stephanov methods allow the directed growth of
shapes like ribbon, or even tubes, however there are many limitations to what
can be done. The Czochralski, HEM, or Kiropolous methods allow the highest
optical quality sapphire, but the result is a rod like “blob” of crystal
called a boule, that must be entirely machined into useable shapes and sizes.
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No, we are a machining company. We don’t produce
any materials, nor do we stock for resale. However, we
do buy materials from which to fabricate parts finished
to customer specification.
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The nature of diamond grinding on ultra hard
materials translates into tight tolerances being routinely achieved.
The actual limits to the attained precision depend on variables like the machine tool
used, the general shape and size of the part, and the sequence of operations needed to
complete the task. Although our shop standard for machining is +/-0.004”, we
generally halve this on the first pass of operations. Secondary operations can further
narrow this to +/-0.0001”. Our flat lapping operations can best be recorded in
millionths of an inch. We welcome discussions about desired tolerances
and often provide constructive advice regarding practical limitations and cost
considerations.
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Insaco is typically capable of generating tightly
toleranced features to .001”, or even .0001”, and in some
cases even tighter. However, since our work is done
by diamond grinding, we do have to have a means to
fixture the piece, also to clean and handle. So extremely tiny
pieces pose special constraints.
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