Archive, Prep – Ransburg M90 Handguns 77073, 77132 User Manual

Page 17

AH-99-01.3

M90 Handguns - Operation

1 3

The object being coated is maintained

at ground potential. The spray gun opera-
tor is also grounded, therefore, the opera-
tor has as much attraction for the electro-
static paint as the object. To prevent
"wrap-back" always keep the gun nozzle
closer to the target than to the operator.

C A U T I O N

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Overlap

For the best "hiding" and uniformity of film thick-
ness, the stroke overlap should be approxi-
mately 50%. There should be some overlap at
edges of the part to increase edge coverage.
Overlap requirements may vary widely with dif-
ferent paint formulations and different composi-
tions of objects being coated.

Triggering

riggering

Gun 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 gun
technique can edge coat in some instances
without making a specific pass for that purpose.
Triggering the gun before the target is directly in
front of the gun may cause heavy edge buildup
on the leading edge of the target due to the elec-
trostatic attraction.

PREP

PREPARA

ARA

ARATION

TION

Paint

A selection of the proper paint mixture is essen-
tial to electrostatic operation. Paint test equip-
ment may be obtained through your ITW Rans-
burg representative. (See IL-259 "REA, REM,
& M90 - Paint Related Information" for paint for-
mulation.) For further paint formulation and test
procedures, consult your ITW Ransburg repre-
sentative and/or your paint supplier.

Fluid Nozzle

Because of the design of the M90 applicators,
the fluid nozzle precision is paramount to proper
function. ITW 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 usu-
ally necessary and wide experience with many
types of coating applications helps. Your ITW
Ransburg representative uses such experience
and actual laboratory testing when recommend-
ing 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 neces-
sary. Selection should always be verified by
actual tests to determine optimum efficiencies.

Refer to Figure 2 "Nozzle Selection Guide" for
the choice of spray width and spray character-
istics appropriate to the size and type of target.
The maximum nozzle flow capacity depends on:
the orifice size, the fluid pressure, the paint vis-
cosity, 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.

ITW Ransburg recommends the use

of a fluid filter to reduce nozzle clogging.

C A U T I O N

!!!!!

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