Uniloy Milicron 500 ton structural foam machine not going into high pressure clamp.

Good morning all,

I have a old 500 ton Uniloy structural foam press at work. Over the last few days its been giving us quite the headache. After doing a Mold change. We went to dry cycle the machine and noticed It wont go into High pressure clamp after the press closes. Pilot pressure is good (1650psi). This machine has a old Maco 8000 system in it that was retrofitted in the mid 90's from Relays/contacts. It uses a linear transducer to locate the platten position which seems to be recognizing the counts correctly. What seems to be happening is when we cycle and watch the timers, it time out at Low pressure and High pressure never kicks in. So the press just stays shut. No power at the high pressure solenoid either. Now whats really interesting is that if I manually push the coil at the main valve manifold, I can get it to snap into high pressure. Which is a bit dumbfounding. Hoping to be able to pick someones brain here a bit to see if resolution can be found. I can provide more details upon request. Thanks guys

Is it possible that the pump is trying to do perform another function such as applying Nozzle Forward pressure and so there is not enough pressure to lock the mold? When you do it manually, the other function is not taking place and so it may be working.
Let us know.
Suhas