Model A7AA Air Assisted Airless Gun
7
2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
In normal operation, the air is turned on just before fluid exits the nozzle
and is turned off just after the fluid stops flowing. This overlap is
designed to eliminate gun spitting.
See Figure 2. When the gun is triggered, the entering air (2) lifts the
piston assembly (1), and allows the packing cartridge (3) and the ball
tip (4) to rise. The rising piston assembly also opens a path for the assist
air, entering at (8). The coating material enters at (7) and passes through
the opening in the seat (5). The coating material exits the nozzle (6),
where it is partially atomized. As the coating material exits the nozzle,
the material stream is further atomized by the assist air which flows
around the nozzle. When the air pressure is removed, the ball tip returns
to the seat and stops the flow of coating material and assist air.
The air piston can be adjusted to provide an air assist on/off function, or
the piston may be set for continuous bleed. This is commonly used on
high speed stitching applications where the cycle time is extremely short.
If faster or slower gun actuation is desired, the packing cartridge
adjuster (9) may be adjusted in or out.
0420002A
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9
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Fig. 2 A7AA Gun
1. Piston assembly
2. Air entrance
3. Packing cartridge
4. Ball tip
5. Seat
6. Nozzle
7. Coating entrance
8. Assist air entrance
9. Packing cartridge adjuster
Theory of Operation
