View Full Version : Need Help! Vacuum Forming Issue: Rough Surfaces

03-17-2014, 11:09 AM
I have a large pyramid shaped mold that I have yet to get a decent part off of. The outside surface of the formed part has a rippled look in some areas. The inside looks textured. The part should be smooth outside and inside.

Mold is 13.5"x13.5"x5" around the base pyramid walls at 30 deg. to an overall height of 16.5"
Mold is smooth.
HDPE 1/8"x24"x24" smooth/smooth

Preheated to 150 deg. F in drying oven
Raised to 400 deg. F by heater banks on machine to compensate for exiting temerature drop
Material is approximately 375 deg. F by the time the mold is introduced

Pre-stretched to provide uniform wall thickness and coverage of the mold.

The bubble looks nice and smooth.

I'm not sure if it is a heat issue, vacuum, material, stretch, etc.
I've tried many recipes and gone through a lot of time and money only to end up with a pile of scrap.

Any help is much appreciated.