| MACOR® |
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Machinable
Glass
Ceramic
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is MACHINABLE with no ordinary metal working tools |
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allows FAST TURNAROUND, no post firing required |
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holds TIGHT TOLERANCES, up to .00005" |
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withstands HIGH TEMPERATURE, up to 1000°C (no load) |
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is CLEAN, no outgassing and zero porosity |
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Properties |
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MACOR®
Machinable Glass
Ceramic has a
continuous use
temperature of
800°C and a peak
temperature of
1000°C. Its
coefficient of
thermal
expansion
readily matches
most metals and
sealing glasses.
It is
non-wetting,
exhibits zero
porosity, and
unlike ductile
materials, won't
deform. It is an
excellent
insulator at
high voltages,
various
frequencies, and
high
temperatures.
When properly
baked out, it
won't outgas in
vacuum
environments. |
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Machining |
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Machining
tolerances are
surprisingly
tight, up to
.0005". It can
be machined to a
surface finish
of less than
20µin.-AA.
Configurations
are limited only
by available
equipment and
the experience
of the
machinist. |
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Sealing,
Joining and
Metalizing |
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MACOR MGC can
also be joined
or sealed - both
to itself and to
other materials
- in a number of
ways: metalized
parts can be
soldered
together and
brazing has
proven an
effective method
of joining the
material to
various metals;
epoxy produces a
strong joint,
and a sealing
glass creates a
vacuum tight
seal. Even a
straight-forward
mechanical joint
is possible.
It can be
thick film
metalized using
metal links, or
thin film
metalized by
sputtering.
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Applications
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Ultra-High
Vacuum
Environments |
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MACOR®
Machinable Glass
Ceramic is used
as an insulator
or coil support
and for vacuum
feed-throughs.
In these
applications,
the conductive
materials are
supported by the
MACOR MGC part
and a compatible
sealing glass is
used to produce
a vacuum-tight,
hermetic seal.
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Constant
Vacuum
Applications |
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MACOR MGC parts
are found in
spacers, heaters
and windows for
microwave tube
devices and as
sample holders
in field ion
microscopes. |
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Aerospace
Industry |
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Over 200
distinctly
shaped MACOR MGC
parts can be
found on
America's
reusable Space
Shuttle,
Orbiter.
Retaining rings
of MACOR MGC are
used at all
hinge points,
windows and
doors.
Also, large
pieces of MACOR
glass ceramic
are used in a
NASA spaceborne
gamma radiation
detector. For
this
application,
frame corners
are joined by a
combination of
machined
(butt-lap)
mechanical
joints and a
sealing glass.
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Nuclear-Related
Experiments |
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Since MACOR MGC
is not
dimensionally
affected by
irradiation,
small cubes of
the material are
machined to a
tolerance of one
micron and used
as a reference
piece to measure
dimensional
change in other
materials. |
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Welding
Nozzles |
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Welding
equipment
manufacturers
are using MACOR
MGC as a nozzle
on the tips of
oxyacetylene
torches. The
material's
non-wetting
characteristic
means molten
particles won't
adhere to and
decrease the
effectiveness of
the nozzle. |
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Fixtures |
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MACOR MGC is
used as an
electrode
support and
burner block in
several
industrial high
heat, electrical
cutting
operations due
to its low
thermal
conductivity and
excellent
electrical
properties. |
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Medical
Equipment |
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Producers of
medical
components are
intrigued by
MACOR MGC's
inertness,
precise
machinability
and dimensional
stability. |
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| With MACOR®
Machinable Glass
Ceramic (MGC),
fabrication is
fast because it
can be machined
into complicated
parts with
ordinary metal
working tools,
quickly and
inexpensively,
and it requires
no post firing
after machining.
That means no
frustrating
delays, no
expensive
hardware, no
post fabrication
shrinkage, and
no costly
diamond tools to
meet
specifications. |
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| The Point is
this: |
| When you
need the
performance of a
technical
ceramic (high
use temperature,
electrical
resistivity,
zero porosity)
and your
application
demands the
ready
fabrication of a
complicated
shape (quickly,
precisely,
privately), look
at MACOR MGC. It
will lower costs
and
substantially
reduce the time
between design
and actual use. |
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Properties
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Technical Data
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| The
general characteristics of this
material described below were
derived from laboratory tests
performed by Corning from time
to time on sample quantities.
Actual characteristics of
production lots may vary. |
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Key
factors for successful
machining are proper
machining speeds and
coolant.
MACOR
Machinable Glass Ceramic
can be machined with
high speed steel tools,
but carbide tools are
recommended for longer
wear.
Achieve the best results
by using a water soluble
coolant, such as Cimstar
40 - Pink, especially
formulated for cutting
and grinding glass or
ceramics.
No
post firing is required
after machining.
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Grinding |
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Diamond, silicon-carbide
or aluminum-oxide
grinding wheels can be
used. |
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Polishing |
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Start with loose
400-grit silicon carbide
on a steel wheel. For
the final polish, use
cerium oxide or alumina
on a polishing pad for
glass or ceramics. A
0.5µin.-AA finish can be
achieved. |
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Sawing |
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a carbide grit blade at
a band speed of 100 fpm.
An alternative is a
silicon carbide or
diamond cut-off wheel.
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Turning |
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Cutting
speed |
30-50 sfm |
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Feed rate |
.002-.005
ipr |
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Depth of cut |
.150-.250
in. |
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Milling |
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Cutting
speed |
20-35 sfm |
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Chip Load |
.002 ipt |
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Depth of cut |
.150-.250
in. |
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Drilling |
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Drill
size |
Spindle
Speed |
Feed Rate |
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1/4 in. |
300 rpm |
.005 ipr |
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1/2 |
250 |
.007 |
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3/4 |
200 |
.010 |
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1 |
100 |
.012 |
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2 |
50 |
.015 |
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Allow at least .050" of
extra material on the
back side for breakout.
This excess can be
removed after drilling. |
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Tapping |
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clearance holes one size
larger than those
recommended for metals.
Chamfer both ends of the
hole to reduce chipping.
Run the tap in one
direction only. (Turning
the tap back and forth
can cause chipping.)
Continuously flush with
water or coolant to
clear chips and dust
from the tap. |
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Composition |
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MACOR
Machinable Glass Ceramic
is a white, odorless,
porcelain-like (in
appearance) material
composed of
approximately 55%
fluorophlogopite mica
and 45% borosilicate
glass. It has no known
toxic effects; however,
the dust created in
machining can be an
irritant. This
irritation can be
avoided by good
housekeeping and
appropriate machining
techniques. The material
contains the following
compounds:
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Approximate
Weight % |
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Silicon -
SiO2 |
46% |
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Magnesium-
MgO |
17% |
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Aluminum -
SiO2 |
16% |
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Potassium -
K2O |
10% |
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Boron -
B2O3 |
7% |
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Flourine - F |
4% |
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Microstructure of MACOR
MGC 5000X magnification
Randomly oriented mica
flakes in the
microstructure of MACOR
MGC are the key to its
machinability.
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