The Rookie
23rd September 2019, 05:15 PM
Back again to get some processing advice :)
I have been working on processing a few new test tube molds and was wondering if anyone has any input on how to eliminate a visual defect I am seeing at the open end of the tube.
Processing Details
- 96 Cavity Valve Gated Hot Runner
- PET with wax additive
- 70F Mold Temperature
- 540F Melt Temperature
Part Geometry
- 0.5 inches outside diameter, 4 inches length, 0.025 inches wall thickness
The waviness is only at the open end of the tube and I have been experimenting with several machine inputs to see the effect of each - shot size, injection velocity, pack time, pack pressure. Without getting into the nitty gritty details of my experiments, I wanted to share some pictures and high level details to see if anyone had any input.
My co-workers suggest that the melt temp is too low, but I wanted to process at the middle of the recommended settings.
Using a consistent shot size, I injected at 100mm/second and 400mm/second. The slower fill speed looked much better visually, but I believe that is due to the momentum of the melt at the end of fill (second picture).
I was not able to see a significant change with pack time and pressure, which makes me believe that something during the first stage of fill needs a little more work.
Photos
https://drive.google.com/open?id=1mmyXhSD7zeJXb3YP8rovIGtUAdtaihLl
https://drive.google.com/open?id=1KCoTYh4A1LXtaH4cpNxXf7dYbtHSIerd
I have been working on processing a few new test tube molds and was wondering if anyone has any input on how to eliminate a visual defect I am seeing at the open end of the tube.
Processing Details
- 96 Cavity Valve Gated Hot Runner
- PET with wax additive
- 70F Mold Temperature
- 540F Melt Temperature
Part Geometry
- 0.5 inches outside diameter, 4 inches length, 0.025 inches wall thickness
The waviness is only at the open end of the tube and I have been experimenting with several machine inputs to see the effect of each - shot size, injection velocity, pack time, pack pressure. Without getting into the nitty gritty details of my experiments, I wanted to share some pictures and high level details to see if anyone had any input.
My co-workers suggest that the melt temp is too low, but I wanted to process at the middle of the recommended settings.
Using a consistent shot size, I injected at 100mm/second and 400mm/second. The slower fill speed looked much better visually, but I believe that is due to the momentum of the melt at the end of fill (second picture).
I was not able to see a significant change with pack time and pressure, which makes me believe that something during the first stage of fill needs a little more work.
Photos
https://drive.google.com/open?id=1mmyXhSD7zeJXb3YP8rovIGtUAdtaihLl
https://drive.google.com/open?id=1KCoTYh4A1LXtaH4cpNxXf7dYbtHSIerd