Rockwell Automation 1771-QDC, D17716.5.87(Passport) CLAMP AND EJECT MODE - Manual (Page 193)

Tune Your Machine
Chapter 10
10-20
Profile Velocity Setpoints
In general, you choose velocity setpoints to move the clamp as quickly as
possible without damaging the machine, mold, or parts. Because of the
nature of the large dynamic load on the clamp, configuring the clamp to
operate at extremely high speeds should be approached with extreme
caution. The moving platen/mold combination, once accelerated to high
speeds, is extremely difficult to slow down in a short period of time.
When configuring velocity profiles:
Start with relatively low velocity setpoints, and....
Incrementally increase those setpoints while observing clamp motion
and repeatability at critical positions in the cycle
Because of the physics involved with inertia and momentum as they apply
to the movement of large masses, remember:
Unless it is a long duration segment, you are consistently below setpoint
on the first clamp close/open profile segment. It takes time for the
hydraulics to overcome the clamp’s inertia and build up adequate
pressure and flow to move the clamp at the requested speed.
Your second and third clamp close/open profiles segments run
consistently higher than setpoint when requesting high speeds. Once the
mass of the platen/mold combination gains momentum, it is very
difficult to decelerate the load to the requested speed.
Low Pressure Close Pressure Setpoints
In general, use Low Pressure Close pressure setpoints that are low enough
to allow unplanned obstructions (such as sprues or un-ejected parts) to
resist mold closure and halt clamp movement before it reaches the mold
safe position. The expiration of the Low Pressure Close watchdog timer
can then be used to signal the PLC processor that a mold protection fault
has occurred.