Updating a very, very old Negri Bossi

[AG8]

We are installing a microprocessor based controller on an old "Piston - non screw" Negri Bossi R5 machine.
Has anyone "out there" have any experience with this machine ?
What purpose does retracting the barrel from mold contact between cycles , have ? Better Cooling ?

 

[MikeHalloran]

Well, the barrel is heated, and the mold is cooled, so it makes some sense to not have the machinery fighting itself when it doesn't have to.
... on the other hand, retracting the barrel on every cycle introduces some complexity.

Since you're adding fancy controls, you could presumably program the machine to work either way, and see how it works out for you.



Mike Halloran
Pembroke Pines, FL, USA

 

[Pud]

Retracting the barrel during (usually, but not exclusively) cooling is called "sprue break".

Often used to keep nozzle tip hot to stop it freezing off and preventing injection on next cycle. Also used with some materials to stop "stringing" of the sprue when tool opens, causing the runner system to hang in the tool.

I would suggest it's important.

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.