“Splay” issue on PA66 GF30% with UV stabiliser.

[Kayl33]

Major issues with what seems like splay marks. Material way in spec in terms of moisture. When purging excess steam comes out of the feed - no manifold leaks present. Any ideas??

This is seen across 3 machines - 3 tools on all same material. 2 drop valve gate.

[Bryan E]

Kayl33
A little more information would be helpful, What are your drying temperatures? What are the barrel temperatures settings on the machine and what are the temperature settings for your manifold and gate drops. When purging excess steam comes out of feed clearly sounds like a moisture issue which would be common across any number of machines, which prompts me to ask what type of dryer are you using? A hot air dryer or one with desiccant? What level of moisture are you seeing. Sorry for all the questions, But from what you have described it sounds like moisture is the problem.

[Kayl33]

Course, yes. Drying temp is 85c dehumidifier dryer. Barrel temps are at 275-295 melt is around 280c all within material data sheet. Moisture check on material checked pre moulding sub 0.18 again within material spec. HR set to 290 6 zones. It can be inconsistent it terms of the splays/silver streaks appearing. Very random. Appreciate the reply!!!!!

[nemanja]

Hi,

What is dwell time, tool temperature, do you have condensation or tool leaking....?
"Steam" can be from stabilising component also. How many % of cylinder volume you inject and what is cycle time?


You can test, "just for fun" longer drying (6-8h), higher drying temperature (up to 100C), increase hot air throughput. Datasheet is just for guideline, often is wrong when you have additional additives inside.

Where is possition of splay marks (close to gate or obsticle)?

[Kayl33]

Hi,
No leaks. Potentially condensation. Tool temp it 60c both FH - MH. Residence time is approx 5mins across barrels of 105mm and 80mm. Yes, already tried the increased temp and time. It’s so inconsistent as it’s running again and ok. “Splay” appear across the part not always as close to the gate though.

Thanks

[nemanja]

You can try to reduce residence time in the material hopper or increase temperature at the material feed (flange). One more option is to increase tool temperature (im working with PA 66 but with fire retardant on 90C).