Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 233)

Tune Your Machine
Chapter 10
10-25
A profile is a series of position and pressure (or velocity) setpoints which
uniquely define a phase of clamp motion. The complexity of the profile
depends on your mold and clamp mechanism.
Velocity Setpoints
In general, choose velocity setpoints to move the clamp quickly without
damaging the machine, mold, or parts. Because of the clamp’s large
dynamic load, be very careful if you configure the clamp to operate at high
speeds because once accelerated, the moving platen/mold combination is
extremely difficult to stop in a short period of time.
When configuring velocity profiles:
Start with relatively low velocity setpoints.
Increase them in small increments while observing clamp motion and
repeatability at critical positions in the cycle.
Because of the inertia and momentum of moving large masses, remember:
Unless the first clamp close/open profile segment is of long duration,
actual velocities generally will undershoot setpoints. It takes time for
the hydraulics to overcome the clamp’s inertia and build adequate
pressure and flow to accelerate the clamp to the requested velocity.
Actual velocities of your second and/or third clamp close/open profile
segments generally will overshoot setpoints. Overshoot increases with
higher velocities. Once the platen/mold combination gains momentum,
it is difficult to slow it to the requested velocity.
Low Pressure Close (LPC) Pressure Setpoints
In general, use LPC pressure setpoints low enough to let obstructions (such
as sprues or un-ejected parts) resist mold closure and halt clamp movement
before it reaches the mold-safe position. Use the low pressure close
watchdog timer to signal the PLC-5 processor that a mold-protection fault
has occurred.
Profile Requirements