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Small Bore Hypotube - Polished Inner Lumen

02/23/2010 5:08 PM

I am looking for a hypotube (stainless steel) with an OD of 0.010" and an ID of 0.005". The challenging bit is that the hypotube needs to be about 1.5m long with a smooth or polished inner surface. Can anyone point me to a supplier with the capability to provide this type of hypotube?

Thanks

EamonB

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#1

Re: Small Bore Hypotube - Polished Inner Lumen

02/24/2010 10:52 PM

The people who make gas chromatographs need long capillary tubes like this, which they pack with a porous filler to obtain a separation of certain gaseous or fluid species.

I am not sure if they go down to this size.

You might be able to plate it onto a drawn piece of plastic that can subsequently be dissolved our or heated to melt it out and clean the innards. The plated surface will be as good as the finish on the plastic core. You will have to vacuum metallize it with aluminium first, for plateability, but a caustic wash will move that out afterwards.

in addition, a simple search gives 63,000 hits.

http://www.google.ca/#hl=en&source=hp&q=%22capillary+tube%22+%2Bstainless&btnG=Google+Search&meta=&aq=f&oq=%22capillary+tube%22+%2Bstainless&fp=7310e1b076ed5f89

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#2

Re: Small Bore Hypotube - Polished Inner Lumen

02/24/2010 10:52 PM

Sorry can't answer that but would be interested to see how this could be done and by whom. I can tell you now that it will be something that could be very fragile. What would you need it for? Micro surgery?

Just interested, Ky.

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#12
In reply to #2

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 7:21 PM

Yes it is a micro-surgery application. The tube has a moving part in the lumen and conventional tubes are too abrasive on the inner surface.

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#3

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 3:29 AM

Does it have to be stainless steel?

I remember seeing a demonstration once (in a sort of public lecture on popular science). They heated up the middle of a glass rod, then, someone ran to the back of the lecture theatre with one end: the result, a very thin long length of fairly flexible glass fibre.

I wonder if you could do the same thing with a glass tube.

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#4

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 4:16 AM

Hi,

no such tube existing.

How do you specify "polished" or "smooth"?.

If you can live with the inner roughness of drawn tubes then no problem.

Tubes for Insulin syringes typically are 0.012" OD.

So get one and inspect and order a full length of tube (5Km or so) to check.

If not ok., then switch to a glass capillary, any diameter any length, super-smooth, can be made by yourself with a glass tube and a flame by simply drawing with adjustable velocity and cooling.

If not possible, then allow 150,000$ and 6 to 9 months to try some exotic procedures:

Make an inner core of a material that can be evaporated completely! (?C02).

Deposit Nickel on this. Heat the arrangement and you will get your tube.

But to make the core will not be done within 7 working days. And to stabilise the core against breakage?

Easiest would be to take the above-mentioned GC-tubes.

RHABE

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#11
In reply to #4

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 6:59 PM

A glass tube will not work as I need some flex in the hypo tube. Stainless steel or nitinol are the preferred materials. The internal bore of drawn tube is normally much rougher than the outside surface. I have taken cross sections and this is almost always the case for small tubes. Post processing is easier at larger diameters. I need the inner to be at least as smooth as the outer.

Eamonb

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#5

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 4:57 AM

I was faced with a similer problem several years ago when developing a jet nozzle for a new type of inhaler to produce aerosol sprays of the order 10 micron. The jet nozzle required was much shorter than 1.5m but the solution that I eventually adopted (and patented for this application) was to Electro Chemically machine a track in a highly polished metal block then to cap this off with another highly polished metal block. This method is not limited in length so it may be applicable in this case. One snag is that this method cannot give you the .010" O/D but is this really required? It will certainly give you the highly polished bore of almost any cross section

An incidental advantage of the ECM method is that the track could be almost any shape in cross section and plan and other features could be built in.

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#6

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 8:59 AM

With a side wall thickness of .0025" this 1.5 mm tube will exceptionally flimsy. Have you considered buying some SS foil? The reason i'm asking is the application APPEARS to be extremely specific. Usually at this point 1 of two things have happened. The designer really does need the ridiculously difficult piece, OR the designer got tunnel vision somewhere and didn't consider a much simpler option.

The question begs to be asked:

Which one do you think happens most? and which happened to you?

can you state what you need this tube for? I tend to specialize in ridiculously difficult projects, but it takes a broad overview to weed out the unnecessary ridiculous stuff from the necessary ridiculous stuff. I have several ideas, one I know will work, but only if you just want this to be a tube.

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#13
In reply to #6

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 7:28 PM

The tube is used in a micro-surgery application. It needs to be a lumen as there is a moving part in the lumen. Conventional lumens of small bore hypo's are too rough for the smooth movement of the part. The part needs to be in the lumen to keep it close to the neutral axis.

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#7

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 9:38 AM

Come on folks. This is certainly not impossible.

Check out k-tube.com or just search for hypodermic tubing.

Sizewise this is no problem. .010 OD X .005 ID is a STANDARD Hypo tube size. #31 Regular Wall.

Lengths well over 1.5 meters are pretty standard.

This stuff is typically welded and then drawn down to size, resulting in an imperceptible weld joint. Plus, many vendors draw over plug or use a floating plug to further smooth the ID.

Smooth is easy, polished is a bit harder. I imagine that polishing could be done by pumping abrasive slurry through the tube. I would talk to the manufacturers about that.

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#8

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 10:10 AM

There is a company in Medway, MA USA that might be able to help.

www.microgroup.com

Good Luck!

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#9

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 12:30 PM

Give these guys a try....I think they got what you need.

http://www.eagletube.com/

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#10

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 1:38 PM

As in Reply from Guest in #8, The basic size is available off the shelf . However, you have to be ready to discuss several issues.

Your actual tolerance needs.

How Smooth, is smooth. Will you want to do profile measurements of the ID by cutting some wall away to get access to the ID. How will you measure ?

Do you need this off the shelf in small amounts, or are you ready to custom order to exact size in small production lots. (This can get you exactly what you want.)

If you order off the shelf from a helpfull source, they will actually measure the various lots they have on hand to find the best fit. (Don't expect special ID finish here!)

For special production lots in this size, try <Internationaltube.com> They work with folks who do this sort of thing as a regular business.

When you get this small, most mills will be, "Sinking," the material to final size. A Floating plug is a good trick, but really tough at this size. Sinking to size, makes it difficult to retain a really smooth ID such as a floating plug could provide.

You could talk to the folks at EXTRUDHONE about the viability of abrasive cleaning of the ID.

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#14
In reply to #10

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 7:44 PM

GA: Extrudehone came to mind almost immediately when I saw the post. Guest (reply #8) got close, but you've hit the target. Their experience should get the job done if it can be done!

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#15

Re: Small Bore Hypotube - Polished Inner Lumen

02/25/2010 11:02 PM

From Tim Hawley Master Mech.

Hello Eamon B,

Accutube has the exact size you are looking for. Check with them pertaining to the I.D. micro-finish.

http://www.accutube.com/accutubeamsize2.html

Best Regards, Tim

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#16

Re: Small Bore Hypotube - Polished Inner Lumen

02/26/2010 1:57 PM

Hi,

pump through polishing: forget about, calculate the flow you need to accomplish the polishing and the flow rate per pressure if viscous flow (Hagen-Poiseuille) and you will see that either the tube will burst by too much pressure or your budget will burst by weeks or months of polishing time.

You did not state if the whole length of 1.5m is necessary for your product or if shorter pieces are finally used.

Floating inner plug not possible with this small ID.

So may be electropolishing may do the internal final polishing, but usually high current densities are used so very difficult to impossible inside small diameter tubes.

RHABE

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#17
In reply to #16

Re: Small Bore Hypotube - Polished Inner Lumen

02/28/2010 4:53 PM

Yes, I need it polished over the full 1.5m length.

Eamonb

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#18
In reply to #17

Re: Small Bore Hypotube - Polished Inner Lumen

03/21/2010 1:34 PM

Eamonb, take a look at this article. Good background. If you have solved your problem, please let the group know.

www.devicelink.com/mpmn/archive/10/03/013.html

from not too smart

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#19
In reply to #18

Re: Small Bore Hypotube - Polished Inner Lumen

03/21/2010 5:45 PM

Thanks for the link. It's a nice review article.

I havent solved the problem yet although we are still working on it.

Eamonb

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