Theory of Operation
3A0294J
7
Theory of Operation
SmartWare shot dispense kits do not use flowmeters in
the material path to measure the volume pumped.
Instead the kit measures the volume pumped by using
the following calculation. See F
. 1 for a graphical rep-
resentation.
Area of the pump piston x distance traveled (measured
by the linear sensor) = volume pumped
When the system receives the start signal, the dispense
valve opens. Once the correct distance is traveled,
which equates to the desired shot volume, the dispense
valve closes and the pump stalls.
Just like a car does not stop the instant you push on the
brake, the SmartWare kit pump does not stop pumping
the instant it receives a stop signal. Therefore, during
the time it takes for the dispense valve to physically
close fluid is still being pumped; the volume pumped
during this time is called the overshoot volume. See F
2 for a a graphical representation.
The SmartWare kit automatically compensates for over-
shoot by taking previous shots into consideration and
then sending the stop signal early.
The pressure transducer compensates for pump travel
during changeovers. Since only a few shots end in a
changeover, this compensation will take longer than the
basic overshoot compensation.
F
IG
. 1: Volume Pumped
Distance
Area
Volume pumped = Area x Distance
F
IG
. 2: Overshoot Volume
Overshoot
Volume
Stop Position
Stop Signal
Start Signal
Summary of Contents for SmartWare 262370
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