Material inside shut off nozzle

[nemanja]

Hello all,

Im running ARBURG machine, 100cc barrel with shut off nozzle (50 tons machine), material is PA GF30. Main problem that i have at this machine is that after some time shut off nozzle stop working. After diassemble im always finding material "behind" nozzle head.
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So far only answer what i got from ARBUG is package with new nozzle, but that didnt solve problem. :(
Is anyone have expirience with this type of problem or any idea for solutions?

Best regards,
Nemanja.

[rickbatey]

I think it may be your heat settings or the design of the nozzle. You may have the heats too high and cooking the resin out leaving just the glass or too cold causing the shut off pin to not close completely. The design of the nozzle may not tolerate glass fibers or isn't made of hardened and coated steel to survive the glass content. Do you need the shut off nozzle? That may be another option.
Can you post some pics?
Rick.

[nemanja]

This machine is specificly orederd for material with glass. Temperature at nozzle is 280C (536F), and that was specified by material data sheet.
We do need shut off nozzle because is vertical machine and we have constant leaking of material if we dont have it, and parts require in each shot same volume.
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What picture can help you more to see problem?

thank you and best regards.

[rickbatey]

A picture of where the resin is getting that it shouldn't. A valve gate in the mold should end your requirement of a shut off nozzle. Is this a Herzog nozzle? If so I think there's something else wrong. When and how do you decompress the screw? When does the nozzle close?
Rick.

[nemanja]

I did try to decompress before and after cclosing nozzle, also i did put ranges for decompression volume from 1 to 15cc, preassure ranges from -100 till 300bar, speed for decompression from 1 to 15cc/s.
Main problem is that machine is orederd for thoes tools and future cangeing on tools is not possible. All i can do now is to try to prevent this problem or propose to my boss to order any different type of nozzle if that can help.
I hope on this pictures will be more clear what problem is.
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Thank you and best regards.

[rickbatey]

Is this a hydraulic nozzle? I think some heat temp adjustment might help but if this unit is pneumatic and you don't have high enough air psi or a boosted air supply, then you just won't keep it working without a unit with hydraulic power.
Most of these units are purchased from Herzog. Maybe you have to contact them and tell them your problems. While I was at another German Tier 1 molder, we ran 45% glass filled ABS/PC without any issues. Have you tried having the pin coated with something like a DLC?
Rick.

[nemanja]

Is hidraulic nozzle. I will try to see if nozzle is from Herzog, and if it is, i will contact them.
We didnt tryed any coating.
As soon as i have new update, ill post here.

TY and BR,
Nemanja.

[Valentin Leung]

I never ran glass material and my questions might be stupid...
-What does the material look like in the area you say it stuck? Is it dry?
-How do you take it off? you wait for it to cool and you cut it off or burn it off?
-Is there any impact in moving the nozzle heat up?
-As rickbatey said, is the pressurized air enough? do you have a dedicated air line for it?
-Can you run another type of material through and see if it's happening?

[nemanja]

I never ran glass material and my questions might be stupid...
-What does the material look like in the area you say it stuck? Is it dry?
-How do you take it off? you wait for it to cool and you cut it off or burn it off?
-Is there any impact in moving the nozzle heat up?
-As rickbatey said, is the pressurized air enough? do you have a dedicated air line for it?
-Can you run another type of material through and see if it's happening?

Hi,
there is thin layer of material on pin that move forward to close nozzle, and it is dry. We remove material with polishing paper, that is usualy enough. Layer of material is not big, but big enough to stop nozzle wrom workin.
Nozzle is hidraulic, and only problem there can be factory settings in machine.
If i heat up nozzle more, there is burned material in end product. Assembly in tool for shot is around 2-3min per shot and shots are realy small.
For now I did try to run also PA GF 6.6 but from different supplayer (higher quality). We will see if problem will be there after biger production lot.

BR,
Nemanja.

[nemanja]

Hi all,

So far i did test few different supplyers of same material, and i didnt had any problem. Looks like main problem was material from that supplyer.
In material that we used before was to much dust, and maybie that was reason for problem.

BR,
Nemanja.