Timing Recipes; Timing Recipe Parameters - Graco Advanjet Diaphragm-Jet HV-2000 Setup And Operation

6. Timing Recipes

Before dispensing can begin, Timing Recipes must be created for the particular fluids
being dispensed. Figure 6-1 on the next page shows the Timing Recipes Menu of the
Advanjet software. Once configured, the Timing Recipes can be downloaded into the
Advanjet controller. After the recipes are downloaded, the controller can be triggered
remotely through digital inputs from the host controller without the Advanjet software
program running in the background.
6.1

Timing Recipe Parameters

A Recipe specifies two timers, Refill Time and Dwell Time, which set the performance of
the jet and the size and volume of the jetted drop. The values for Refill Time and Dwell
Time depend on the rheology of the fluid to be dispensed and should be chosen to
optimize jet performance and dispense quality.
Refill Time is dependent on viscosity, temperature, and fluid pressure. For example, for
a UV adhesive with 1,000 cps, a typical refill time might be from 1.7 to 2 msec with fluid
pressure at 15 psi. It is best to determine the Refill time through application testing. Too
much refill time could cause accumulation of material on the nozzle tip. Not Enough refill
time could result in a poor quality drop or a missed drop.
Specifically, without sufficient refill time, the jet will be ―starved‖ and the drop size could
be inconsistent. A pattern of large and small drops is usually a sign that the jet needs
more time to refill. If this pattern is observed, increase the value of Refill Time until the
drops are consistent and stable. Alternatively, if a specific drop rate is desired, increase
fluid pressure instead of refill time.
Dwell Time controls the time for the material to flow out the nozzle orifice and form a
drop. In DROP mode (see Section 6.3), the value of Dwell Time is usually not important
since its duration is small compared to the motion time of the robot moving from one
position to the next. However, in LINE mode the Dwell Time is important and sets the
drop cycle time (see Section 6.4).
Drop Cycle Time: The following formula gives the relationship of drop cycle time, drop
spacing, and robot velocity:
V = ∆X / ∆T
Where V = Robot Velocity, ∆X = Desired Drop Spacing, and ∆T = Drop cycle time
(Drop cycle time = Refill Time + Dwell Time).
Additional time values give the jet a little extra time for the first drop to be ejected. This
is useful with materials that are ―shear thinning‖ and/or need a little extra time initially
after being idle for a period of time. In either the DROP mode or LINE mode, the extra
time is added to the Refill Time to adjust the time for the first drop.
Page 26 of 60 Advanjet HV-2000C Jet Controller Setup and Operation 3A5856A