Felt Dies

Peter,
What I think Tuber is doing is not unlike what you describe but originally in making polyimide tubing there was a company in Cinnaminson,NJ (George___) and he had a patent that coated wire with teflon and then you coated the teflon with polyimide. the teflon in theory allowed you to slip the conductor out of the coating leaving you a tube. There are other ways to do this.

The tubing has a variety of uses and the original use was as a conduit for electrical leads from a pacemaker worn outside the body to the attachment points on the heart. As technology evolved, the pacemaker was placed under the skin. The tubes were still used or needed. Medical applications are as varied as a researchers imagination. Other uses are as insulating sleaves ielectrical devices that have nothing to do with medical things.

Another use was for cardio catheters where the tubing becomes a part of the catheter and may be used to deliver tools and applicance to blots and blockages etc.

Tubing had a lot of good properties which made it ideal for this medical application. What it did not have was radiopacity and good torsional strength. Attempts to solve the radiopacity started with materials being added to the polyimide and it was mildly succecssful. A very fine SS wire was also embedded in the wall of the tubing. This worked sometime well but did not solve torsional problems.

Someone not sure who thought up the idea of putting a braid over the polimide wire and then putting more polimide over the braid. The interstices and the nubmer depend upon how dense the braid, diameter of the braid material compared to the tubing diameter, etc. Again I am sure that the various companies have their own preferences in doing this.

Just a little of what I know of tubing. Perhaps Tuber can share more info with us.

You are correct. I make medical and electronic tubing. The devices have progressed dramatically over the years. The braid reinforcement solves the torsional issues. My dillema is filling those voids caused by the overlapping braid wires without trapping air. As you know, polyimide only likes to be cured in very thin layers. We do a pretty good job, but I am always looking for better methods. We have solved this problem when placing thermoplastics on top of the braid, but I'd like to better our yields on the polyimide topcoats. The majority of these products are now made in Trenton, Georgia, Chatanooga, Tennessee and Tampa, Florida. I've never heard of the NJ company you mentioned, but there is a company in Putnam, Connecticut that does some polyimide. I still go back to my original questions. What felt? What enamel? Prewetting or not? Prewetting with what? I do not find the virtual trade show very helpful. Also, other plastics in solution? Put your thinking caps on.

Hi Richard,

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Re tube making:

Yes Richard we were making heavy duty hydraulic and pneumatic hoses for boats, semi-truck trailers, tree cutting machines and so on.

Best regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Tuber,
That being said are you at the Rossville plant, the former HV, PD, or Roger R.'s in Tampa.

The problem with polyimide is that it is very low solids and high solvent. The difficult thing is to get as much as the solvents our that you can without it skinning over and trapping air. There is a way and it involves dies.

Just remembered the owner of the NJ company was George Rogers. He would be in his 80's now.

Tuber,

So where are you working?

There are ways to do this. Polyimide is low solids and you have to put it on thin because of that. It is also temperature sensitive. I think the problem can be solved with appropriate dies.

I do consult. I live in Chattanooga. 423-266-3667

I'll bite. I may be interested in a technical relationship. Do you like Tampa? What's the Rossville plant? I'll call you to discuss. Who should I ask for?