Re: White streaks or spots
N.B: I think that is a fiber accumulation.
Re: White streaks or spots
Is the location of the defect always the same, or is it random? Where is it in relation to the gate? Is the problem consistent throughout the run, or is it better/worse at start up? If it is segregated fiber at the surface, you might be able to bury it by raising the mold temp to 90 - 95C.
Re: White streaks or spots
Hi,
1- yes the location is the same.
2- the part is like a "cup" and the location of the gate is in the bottom "direct injection", the defect is between 30/50 mm/Sec (between 30/60 mm for injection course).
3- No, the defect appeared in all parts between 30/60 in the injection course, but sometimes it appeared at the start of the injection.
4- the defect appeared internally in the parts and externally it appeared a few times.
Re: White streaks or spots
Based on your description listed above and the defect shown I would suggest you check your nozzle heater bands and or thermocouple. It appears your injecting a cold slug of material because of the direct gating.There is no other place for the cold slug to go except for the surfaces of the part. All too the nozzle thermocouple is placed directly under a heater band causing the heats to appear to be up to temperature but actually be much lower.
Re: White streaks or spots
thank you I will check them.
Re: White streaks or spots
Greetings;
I would suggest looking at your dryer also. Drying temp? Drying time? Dew point? Does the part run well for a while after it has been down and then start with the streaks? Does the material pop and hiss when purging?
Just something else to look at
Re: White streaks or spots
thank you for your suggestion, I will check them.