Molded Part - Low tensile yield

[titus9027]

Hi,
Here to inquire;
1. reason why glass fiber orientation change or different within 1 mold long connector?
2. reason why different in plastic parts tensile strength between 2 cavities from same shot?

Thanks,
SM

[Suhas]

Hi SM,
As I understand, you are asking why is there variation from shot to shot in orientation and tensile strengths - correct? If yes, the process you are using is not robust. The plastic is not getting into the mold the same way every shot - may be the injection speeds are very low, melt and mold temps are very low, etc. Not sure if this helped you, if not let us know.
Thanks,
Suhas

[Maheshkumar Hiremath]

Hi SM,

For which plastic material are you facing this problem ?

What are the process variation for Melt cushion and inj pressure and dosing time ?

Thanks ,
Maheshkumar.

[rickbatey]

Also note that glass filled resins need more gate orifice due to their reduced flow, and often times the gates are too small. The resin is then subjected to excessive shear heating, and often times the glass fibers will be broken and cause a loss of properties. I also see too low of melt and steel temps used for glass filled resins, which leads to poor glass distribution and wetting of the fibers.

Rick.

[pjhall]

To add to Rick's reply...Also use the largest nozzle tip orifice possible especially for long glass fiber. Give us some more information and we might be able to help.