Cushion Issue with a Toshiba EC390 17AT machine

[Brian Snider]

I have been working on an issue we are having with one of our Toshiba machines. We are running 60% long glass material in our process. we have developed an issue with not being able to hold a consistant cushion while runnig this process. The shot size is 219 mm. 1300 BP. We have a tolerance of 2.5mm on a 12mm cushion. We are running in continious cycle with a robot.
My first question is, is there anyone out there running this same type of material and machine? and has anyone came across this simular issue.

Brian Snider

[rickbatey]

How long have you been running this resin on this press and how old is the press? I ask because too many companies purchase a base press and injection unit without thinking about the resins that will run in it. Depending on age and time ran, my first guess is worn NRV (screw tip, seat and check ring) or worn barrel and/or screw.
Run a check ring test. Shoot 5 parts with hold time but NO pressure. Weight them and the range should be less than 5%. More than that and you need to tear it down and inspect the components; ALL of them.
Rick.

[Brian Snider]

Rick, Thank You for the reply. We have replaced the Barrel, Screw and Non return Valve. Check ring test result in 4 out of 5 ok but the 5th one fails. Have incrteased back pressure to try and compress material in case of possible air pockets. I welcome any suggestion, I have been stumped on this one. Not sure what to do next.

[rickbatey]

What are the actual on the press (peak injection psi, shot and cushion, back psi, actual extruder psi, barrel settings, injection, recovery, cooling and cycle time) ? Is this resin FR or UV stable? More answers might point out other root causes.
Rick.

[Brian Snider]

Yes I agree Rick...I have some of the numbers, will get the rest. I am hoping by throwing this out there maybe somone else will see something I am missing. Thanks for the reply. Really looking forward to finding the root cause of this one.

[rickbatey]

Brian, it may be as simple as the heat settings are too low causing the glass fibers to be more abrasive. BTW- does this run 24/7 or is it shut down? Could be due to shut down and start up procedure as well.
I still wonder if you have the best injection unit components for a resin with more glass than polymer!?
Rick.

[Suhas]

Good discussion all. Brian, do the rest of the outputs (inj press, fill time, screw rec time,etc ) stay consistent? I had run this type of material one and ended up 'collecting' a lot of glass fibers in the nozzle adapter causing a lot of inconsistency.
Suhas