For the best "hiding" and uniformity of film thick-
ness, the stroke overlap should be approximately
50%. There should be some overlap at edges
of the part to increase edge coverage. Overlap
requirements may vary widely with different paint
formulations and different compositions of objects
being coated.
Triggering
Applicator triggering (ON/OFF) depends largely
on the desired results (the amount of wraparound
required, edge coating, etc.). If the front and back
of the object are being coated, proper applicator
technique can edge coat in some instances without
making a specific pass for that purpose. Trig-
gering the applicator before the target is directly
in front of the applicator may cause heavy edge
buildup on the leading edge of the target due to
the electrostatic attraction.
PREPARATION
Paint
A selection of the proper paint mixture is essential
to electrostatic operation. Paint test equipment
may be obtained through your Ransburg repre-
sentative. For further paint formulation and test
procedures, consult your Ransburg representative
and/or your paint supplier.
Fluid Nozzle
Because of the design of the AA90 applicators,
the fluid nozzle precision is paramount to proper
function. Ransburg makes every effort to assure
that all production of this part will meet the critical
design standards necessary for all applications.
The selection of the best nozzle to apply a given
coating to a specific article with maximum effi-
ciency is not an exact science. Testing is usually
necessary and wide experience with many types
of coating applications helps. Your Ransburg
representative uses such experience and actual
laboratory testing when recommending a nozzle
for your application needs.
However, if parts, paints, or conveyor speeds are
changed, a different nozzle may be required for
best results. The following discussion and guide
will assist the user in making their own nozzle
selection whenever it becomes necessary. Se-
lection should always be verified by actual tests
to determine optimum efficiencies.
Refer to "Nozzle Selection Guide" , Table I in this
section for the choice of spray width and spray
characteristics appropriate to the size and type
of target. The maximum nozzle flow capacity
depends on: the orifice size, the fluid pressure,
the paint viscosity, and the spraying temperature.
Always remember, for maximum paint economy
any nozzle selected should always be operated
at the lowest fluid pressure, which will give good
atomization and the required flow rate.
Ransburg recommends the use of a fluid
filter in addition to the filter in the applicator
fluid line to reduce nozzle clogging.
C A U T I O N
!
The object being coated is maintained
at ground potential. The applicator opera-
tor is also grounded, therefore, the operator
has as much attraction for the electrostatic
paint as the object. To prevent "wrap-back"
always keep the applicator nozzle closer to
the target than to the operator.
C A U T I O N
!
Vector AA90 Applicators - Operation
25
AH-07-01.10
