Suck back to set check ring, .... is telling what?

[Joel JS]

Hello,

Wanted to poll the experts here.... we have a 500 ton machine, (sorry I don't know the screw size as yet) and if you don't have at least 10 mm of suck back (on at least two different materials I have seen) the check ring does not set, and it will not hold a cushion.... does this mean the screw/tip assy is worn out and needs to be replaced, or is this just normal/ok?:)

thx! Joel

[iautry1973]

Have you tried a fast injection stroke at the beginning to "set" the check ring? So if your shot size is 2.3" + .25" decompression go with a fast speed to 2.3".

[brentb]

What kind of NRV? Does it have a castellated ring/tip?
At least give machine make and/or model!

KOM
brent

[Joel JS]

Have you tried a fast injection stroke at the beginning to "set" the check ring? So if your shot size is 2.3" + .25" decompression go with a fast speed to 2.3".

thanks, yup I've seen that too..... for this last job I had to fill slow at the beginning for cosmetic reasons.... but I also remember that press requiring more suckback (than i thought it needed) for another job too.

thx! Joel

[tbramel]

We have Ferromatik/Milacron and Milacron/Elktra machines (650T / 80mm) that we have to use 8mm to 10mm decompress to get a consistent cushion. Running PP. SAN and GPPS.

[Joel JS]

We have Ferromatik/Milacron and Milacron/Elktra machines (650T / 80mm) that we have to use 8mm to 10mm decompress to get a consistent cushion. Running PP. SAN and GPPS.

OK.thx..... our screw is also 80mm (found out later) .....sounds like we are in the ballpark. Thx!
Joel