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Theory of Operation
Overview
The DJ-9500 is a normally closed, air-actuated, spring-return mechanism, which uses momentum transfer
principles to expel precise volumes of material. Pressurized air is regulated by a high-speed solenoid to
retract the Needle Assembly from the seat. Fluid, fed into the fluid chamber, flows over the seat. When
the air is exhausted, the needle travels rapidly to the closed position, displacing fluid through the seat and
nozzle in the form of a droplet. Multiple droplets fired in succession can be used to form larger dispense
volumes and lines when combined with the motion of a dispenser robot.
Adjustable Features
The following features affect performance of the DJ-9500 and are typically adjusted to fit your application.
Fluid Pressure
Fluid Pressure should be set so that fluid fills to the seat, but should not be influential in pushing the fluid
through the seat and nozzle. In general, higher fluid pressure results in a larger volume of material jetted.
Stroke Adjustment
The Stroke Adjustment controls the travel distance of the Needle Assembly. Turn counterclockwise to
increase Needle Assembly travel, turn clockwise to decrease travel. An increase of travel distance will
often result in a larger volume of material jetted.
Solenoid Valve
The Solenoid Valve controls the valve operation. When energized, it allows air in the jet air chamber to
compress a spring and thereby raise the Needle Assembly. When de-energized, the air is released and the
spring forces the piston down so that the needle tip contacts the seat. The valve ON/OFF times can be
adjusted in the Fluidmove software.
Seat, Nozzle and Needle Assembly
Seat, Nozzle and Needle Assembly geometries are typically the main factors controlling volume. Size is
determined based on the application and fluid properties. Other parameters are adjusted in accordance
with seat, nozzle and needle assembly choices. Sizes are listed in Table 8-1.
Active Nozzle
The Active Nozzle controls fluid break-off and minimizes accumulation at the nozzle tip.
Thermal Control Assembly
Fluid temperature often influences fluid viscosity and flow characteristics. The DJ-9500 is equipped with
a Thermal Control Assembly that assures a constant fluid temperature.
Dot and Line Parameters
In addition to the DJ-9500 hardware configuration and settings, Dot and Line Parameters are set in the
Fluidmove software program to control the size and quality of dots and lines dispensed. For information
on dispense parameters, refer to the Fluidmove User Guide or Online Help.
Theory of Operation
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Troubleshooting
