Heat forming of plastic tubes

[basenxuser]

Hi all,

I am looking for a right advice on a process to form plastic tubes into shapes as desired.

Say e.g. S-shape is required, i am thinking of a metal fixture containing the shape, so that i can heat the hollow tube in the fixture by placing it into the cut shape.

Here i need help on the critical process parameters like temperature and dwell time to achieve greater shape retention properties.

My material is Nylon spl. grade.

Thanks in advance,

 

[patprimmer]

There are many types of nylon ad each has its own melting temperature and they cover a wide range.

Most common nylons cannot he thermoformed as you suggest as they have no rubbery or soft stage, but pass very quickly from rigid to liquid.

They also absorb moisture from the atmosphere and outgas if heated to moulding temperature before they are dried.

Regards
Pat
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[btrueblood]

What Pat said regarding nylons.

I've had some success in hot forming PE and PP tubes, but typically by heating to the softening point in an oven, then placing into a room-temp. mold or form to chill. Slow process, but works ok for R+D. Warning - you will not have the same material properties after such treatment, a great deal of the strength of polyolefin tubing is (I believe) in the amount of cold work done during the extrusion/forming process. It's also almost impossible to control wall thickness of softenend, hot, poly tube as you bend/stretch/blow it to a new shape, and that will also affect pressure strength of the tube.

 

[basenxuser]

Thanks pat for
"Most common nylons cannot he thermoformed as you suggest as they have no rubbery or soft stage, but pass very quickly from rigid to liquid."

it throws me light into new dimensions

Thanks btrueblood too for sharing your thoughts..