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Manual and Automatic
Vacuum Potting and Encapsulating Systems
Dispense air-free, accurately metered, mixed
and dispensed
epoxies and urethanes into APT vacuum chambers for
superior penetration and void-free vacuum cast parts.
Vacuum-potted components ranging in size from automotive
ignition coils to large MRI body-
imaging coils often require air-bubble and void-free penetration of the mixed
epoxy—around
every turn of wire and under hard-to-reach overhanging ledges.
When connected to one of our ECS-Series or HT-Series metering, mixing and dispensing
machines, our complete vacuum potting and encapsulating systems are equipped to precisely
control your formulation's ratio, shot-size and output rate — to deliver air-free
material into
your molds at precisely preset and controlled vacuum levels. The resin degassing
tanks
connected to the dispensing machine can be equipped for either batch or continuous thin-
film resin degassing.
Typically, digitally-controlled vacuum at better than 0.5 mmHg is continuously drawn on
the
resin materials in the supply tanks, while high-voltage components to be potted inside the
vacuum chamber are also digitally maintained at a precise vacuum level to insure
bubble-free
casting of on-ratio, abrasive-filled mixed material, into those mold cavities.
High-voltage
electrical and electronic components demand vacuum potting, however other critical
air-free
applications, including vacuum-assisted RTM, utilize vacuum casting to produce void-free
parts.
APT's metering and mixing systems feed air-free mixed material to both standard and
custom-
built vacuum chambers to produce the highest quality, void-free parts. What size or
type of
chamber is right for your application? Our people can work with you to select one of
our
existing manual or automatic chambers or we can design one that meets your specific
application requirements. They include automatic valves for connection to the vacuum
pump
and for venting vacuum to ambient pressure.
 
Shown below is a dual-box vacuum
chamber. While parts are being automatically poured inside
the chamber on the left, an identical chamber on the right lowers its automatic elevator
base to
permit finished potted parts to be removed. Note that there are four individual
shutoff nozzles
at the top of each chamber to allow the system to sequentially pour into each mold cavity.
Due
to the absence of air, it can take a while for the mixed material to flow by gravity and
fill voids
down inside the assemblies. Multiple-pass pouring eliminates over-filling by
allowing you to make
a series of programmed shot volume displacements into each mold cavity (including a final
"top-off" shot), just prior to opening the chamber and removing the parts.
The two chambers shown below have
front-opening doors, lighted sight-ports, automatic
vacuum valving and mixed material inlet valves. The vessel on the left has a
manual
turntable inside the box, plus a vacuum-sealed horizontal rod running through the
chamber,
which lets the operator accurately position the shutoff nozzle over each mold
cavity. The
larger chamber on the right has a 36" diameter hinged door.
 
When potting trays of parts with
numerous cavities, digitally controlling a single pour nozzle
often answers the need to eliminate maintenance on multiple pour nozzles. In the
fully automatic
vacuum boxes shown below, a single pour nozzle is driven from part-to-part with a
servomotor-
controlled, X-Y-Z Axis, pour tube positioning system. With these systems, the
operator simply
places a long tray of parts to be potted on the z-axis base inside the chamber and presses
the
start button. Sensors at the edge of each tray detect that tray's identifier and
communicate with
the PLC to automatically preset the ratio, shot-size, output-rate and all indexed
movements of
the pour nozzle from one mold cavity to the next. At the end of the automatic
sequence, the
chamber door automatically lowers and the tray of parts is removed for post curing.
  
Vacuum Levels Required for Degassing Resins
and Potting Components Under Vacuum:
30" Vacuum = 0.0 mmHg (Torr) = 0.0 microns = Perfect
Vacuum
0.05 mmHg (Torr) = 50 microns
0.1 mmHg (Torr) = 100 microns
0.5 mmHg (Torr) = 500 microns (Resin is degassed at 50 to 500 microns to
vacuum
pot and encapsulate high voltage components.)
1.0 mmHg (Torr) = 1,000 microns (In-chamber vacuum levels from 500 to 1,000
microns are required for most vacuum potting and encapsulating applications.)
2.0 mmHg (Torr) = 2,000 microns
5.0 mmHg (Torr) = 5,000 microns (2 to 5 mmHg is needed to make low to medium
viscosity resins visibly air-free. This range of vacuum levels is five to ten times
better than 29" of vacuum.)
10.0 mmHg (Torr) = 10,000 microns (Very little degassing is done at this level.)
29" Vacuum = 25.4 mmHg (Torr) = 25,400 microns (Not a
sufficient
vacuum level for degassing most epoxy and urethane resins.)
28" Vacuum = 50.8 mmHg (Torr) = 50,800
microns
15" Vacuum = 381 mmHg (Torr) = 381,000 microns
0" Vacuum = 762 mmHg (Torr) = 762,000 microns = Ambient Air
Accessories:
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Light-Sensing Vacuum Traps
Eliminate costly vacuum pump rebuilding and cut downtime.
This liquid trap stops foamed resin from flooding the vacuum
pump while degassing. When the glass-tube receiver has just
30ccs of resin inside, the light-beam and reflector sense it, the
valve closes, an alarm sounds and the flood of resin stops.
The receiver (see inset) comes apart four pieces for easy
cleaning. |
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Vacuum Pumps
11-, 20-, 55-, 100-CFM and larger are available from APT.
Complete assemblies include a motor-starter, a manual switch
mounted on the control panel, a bleed valve and an analog gauge
on the tank lid, plus plumbing to the tank. An optional electronic
vacuum sensor, mounted on the tank lid with an automatic control
valve, can hold preset vacuum setpoints on material in the tank.
Preset vacuum levels can optionally be entered at the operator-
interface control panel on the meter/mix machine. |
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The
Heateroll® - 55-Gallon Drum Heating/Melting Oven
Melts one drum, fast. The combined heating and
rotating action
of the The Heateroll® typically preheats drums 6 to 8 times faster
than conventional "stand-up" drum heating methods. Operates with
ceramic-enclosed infrared heaters. Saves energy and minimizes
thermal degradation of the material. Inset shows the Heated
Compartment, which slides over the drum, in the closed position.
Temperature Range: 90oF to 200oF. Keeps filler in suspension.
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Note:
Resins typically require precise (± 2°F) temperature-control, agitation and
vacuum degassing to significantly lower the resin's viscosity and surface-tension - to
remove all the air and dissolved gasses - prior to metering, mixing and dispensing into
molds inside chambers. APT's Batch Tanks and Continuous Thin Film Deaerators prepare the resin
materials for short-run vacuum casting and continuous vacuum casting. Various levels
of vacuum degassing (down to the micron level) are required for different applications.
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