Machineable Ceramics (A1)

Aremco offers a broad range of machinable and fully-dense ceramic materials for
applications in which high temperature insulation, thermal shock resistance and high
dielectric strength are required. Aremcolox™ and Super-Heat ceramics include
compositions based on alumina, alumino-silicates, boron nitride, glass-ceramics,
magnesium oxide and zirconium phosphate. Production capabilities include isostatic and
dry pressing, low pressure injection molding, extrusion, slip-casting, and CNC machining.

TYPICAL APPLICATIONS
Aerospace Gas nozzles, thermal insulators, space mirrors, and nose cones.
Automotive Diesel port liners, manifold insulation, catalyst support systems,
flow separator housings, regenerator cores, turbine nozzles.
Electrical Connector housings, heater and resistor supports, stand-offs,
instrument and appliance insulators, coil forms and bobbins.
Electronics Wafer chucks, insulators, vacuum tube structures, microwave
housings, arc barriers, x-ray equipment, and PVD applications.
Heat Treating Brazing/carburizing fixtures, induction heating tubes, furnace and
tooling insulation, kiln furniture, welding jigs, hot forming dies.
Metallurgical Molten metal crucibles, nozzles, troughs, liners, transfer rollers,
structural parts, filters, thermocouple sheaths, permanent molds.
Petrochemical High temperature corrosion and wear resistant components.
Plastics Hot die parts for thermoplastic forming equipment.


Aremco can supply all grades of ceramic as finished parts. In addition, Aremco
offers parts manufactured in other ceramic materials including cordierite, Macor®,
mullite, silicon carbide, silicon nitride, steatite, and zirconia.

Firing (502-1100)


Aremco's Econo-Heat™ Series furnaces are ideal for firing
502-1100 ceramics. Refer to reverse side for detailed product
specifications. Follow the procedure below.
a) Bake out at 200 °F for two hours to remove moisture. Failure
to eliminate moisture prior to ceramic reaching elevated
temperatures will result in cracking or shattering.
b) Increase temperature at a rate of 200 °F per hour maximum
(slower for thicker sections) to 1100 °F. Soak at 1100 °F for
six hours.
c) Increase temperature at a rate of 200 °F per hour to 2050 °F.
Soak at 2050 °F for 30 minutes for each 1/4" of cross-section
(i.e. - soak a 1/2" thick part for one hour).
d) Turn off furnace and allow to cool to below 150 °F before
removing parts. Do not open furnace door until temperature
is below 150 °F.

Firing (502-1400 Bisque)


This product has been pre-fired to 2475 °F. To achieve high
density, hardness and strength, fire to 3075-3125 °F. A 15-18%
shrinkage should be expected. Raise temperature 500 °F per
hour to 2000 °F, 200 °F per hour to 3125 °F. Soak for 12 hours,
then cool in furnace to room temperature.

Special Machining Notes - Aremcolox™ 502-1100


a) Typical tolerances for fired parts can be held to ± 1% or ±
.005" whichever is greater. For tighter tolerances it may be
necessary to wet grind after firing.
b) Machine all dimensions 1-2% undersize to allow for
expansion during firing. All dimensions including centered
and off-centered internal holes will increase by this
percentage after machining.
c) In order to fire the material properly, it is desirable that cross
sections be held to 3/8" maximum. Hollow cut or drill thru
holes in the unfired ceramic to maintain a 3/8" cross-section.
When it is necessary to exceed 3/8", a slower rate of firing
should be used. Cross-sections should not exceed 5/8". Drill
longitudinal holes through round stock.

Equipment


Conventional machine shop equipment can be used with
excellent results. Note that an abrasive slurry or ceramic dust
will be generated during the machining process. Make sure to
use dust collection equipment as required and to clean the
equipment thoroughly after use.

Tooling


Aremcolox™ 502-1100 Unfired, 502-1400 Bisque-Fired, 502-1600
and 502-1800 may be machined using standard high speed
hardened steel tools for short runs and carbide tipped or solid
carbide tools for longer production runs. Follow the tooling
recommendations on the adjacent chart for machining 502-400,
502-600, Macor ® and Low Density 502-1550. Aremcolox™ 502-
1100 Full-Fired, 502-1400 Full-Fired and 502-1550 Medium and
High Density may only be machined using diamond tooling.

Fixturing


Hold the ceramic carefully so as to prevent chipping or cracking.
Place a soft paper sheet in between the gripping jaws and
ceramic as required. Support ceramic plates for drilling or milling
operations by using a soft backup block and temporary adhesive
such as Aremco's Crystalbond™ 509. (Refer to Technical
Bulletin A9.) Support cylinders using an internal metal sleeve.
Do not use pointed screws to hold workpiece since ceramics are
brittle.

Lubricant


Dry machining is recommended for 502-1100, 502-1600 and
502-1800 since these ceramics have a high open porosity and
will absorb water readily. A water or low concentrate lubricant is
recommended for 502-400, 502-600, 502-1400, and 502-1550.
Where required, a continuous stream of lubricant should be
directed at the work and tools to prevent chipping and tool wear.

Cleaning


Clean parts after machining, and bake out at 200 °F for two hours and 250 °F for another two hours to remove residual
lubricant. Clean fire as required up to 1000 °F to remove any discoloration due to lubricant.