Bump Polyimide Tubing

use an extruder which melts the raw materail then forces it out over a round die where the operators pinch the tube and the draw pressure and speed determine the drawdown size of the tubing. Check this with a Micrometer, internal and external. Cool with water at the approp lenght to allow the materail to hard enough to be coiled onto spools.

in other words a lot of prastice, planning and expertise of the operator will be needed to make tubing with different internal size in the same coil of tubing. It is almost impossible to increase the internal size unless you install a very sensitive compressed ait port in the die used to size the materail out of the extruder head. The pressure and speed at which you pull or draw on the materail will decrease it and where the water hits the materail will also decide the internal dia.. You would almost need a computerized controller that could handel 4 or 5 differnet preprogrammed setting to get a lenght of tubing with increasing and decreasing diameters along a lenght of tubing. The compressed air from the die even low pressure could cause a blow out in hot spots of the extruder head. Extruder head heater is have seen vary in temp with each use a few degrees till they burn out. GOOD LUCK

how many million feet of this do you want to run? Might be easier to run in a "corregator" type line with a cutter in concert with the shape sequencing

- also, may require a "programmable parison controller" similar to those used in the bottle industry to help vary the wall thickness at the die head so that as the OD and ID is varied the wall can remain relatively 'constant'

good luck

Jim

Have you read about the polyimide? Here's the link for the article
http://www.profma.com