Night Mode Capability; Fully Automatic Circulation Shot Repeatability Test Results - Graco HFRL Setup And Operation Manual

Appendix H- Circulation
If enabled (checked), the logic will pressurize the mate-
rial lines prior to opening the dispense valve, based on
the settings of the "Controlling/ Stall Pump," "Minimum
Stall to Pressure" and "Maximum Pressurize Time" set-
tings on the same screen. For example, using the set-
tings from the screen shown in F
50 cc/second produces 100 bar of pressure on the blue
pump, the system is circulating at 20 cc/seconds.
When the dispense request occurs, the pumps will
accelerate to the 50 cc/second flow rate while circulat-
ing, then the pressurize state will start by closing the
circulation valves. The pressurization process will con-
tinue until either the blue pump pressure reaches 86 bar
(86% of 100 bar = 86 bar), or 3000 milliseconds (3 sec-
onds) time has elapsed. Once the pressurization pro-
cess is complete, the dispense valve will open, starting
the dispense process.
To ensure this process works properly, the material
hose diameters must be sized correctly to ensure both
materials reach the correct pressures at the start of the
dispense, as well as the end of the dispense. The
thicker the return line hoses, the more time is required
to pressurize the lines. It is recommended that "Mini-
mum Stall to Pressure" settings of 75 – 90% are used.
Furthermore, the pump recirculation pressures should
be less than the dispense pressures, and the "Maxi-
mum Pressurize Time" setting should exceed the typi-
cal amount of time required for the pressurization
process.

Night Mode Capability

HFR systems with the "HFR Recirculation Valves
Installed" feature a night mode selection capability. The
user can select Night Mode, which allows the pumps
and optional heating zones to be turned ON periodically
or at a future time or date. Refer to Conditioning #3
Setup Screen descriptions in earlier sections of this
manual for how configure night mode operation.
F . 44: Night Mode Operation
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114
. 43, if a dispense at
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Fully Automatic Circulation Shot
Repeatability Test Results
Some informal CPK type tests were performed to com-
pare the dispense amount consistencies of a dispense
in the Full Automatic mode, with the same requested
amount with the "Auto Circulate Between Dispenses"
feature turned OFF (a standard stall to pressure type
dispense). The dispense size chosen was relatively
small for the HFR pump sizes used. The flow rate
selected was also relatively slow for providing good
shot repeatability numbers. Different circulation and
dispense flow rates were also used, forcing the HFR to
speed up, then slow down after the dispense operation.
As shown in F . 45 and F
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cies provided when the HFR was dispensing with the
Fully Automatic Circulation feature ON was roughly
twice as good in comparison to the same sized dis-
pense using a standard stall to pressure type configura-
tion.
Even though both tests had the same requested dis-
pense amounts entered, the Automatic Circulation dis-
pense provided less dispensed material since the
dispense pressures were lower. If the requested
amounts were larger, the two configurations would pro-
vide closer average or mean dispense amounts.
Different test results may occur, depending upon on the
dispense amount chosen, pump sizes, and other fac-
tors.
. 46, the amount consisten-
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