You need a laser micrometer

Hi,

I have been contacting laser companies and they say lasers are best for OD...if anyone has a company in mind, that would be great.

Thx.

Sue

Try these

It could be possible to use a pneumatic gage. It was used to measure down to 1µm=1E-6m. I think it could be a solution.

Would it be possible to fill the tubes with liquid, and weigh the filled tubes, or measure the liquid used? If you know the length, and the volume, or weight of the fluid, the only variable would be the ID. Good luck.

I don't understand how you can expect to measure a tube ID to that accuracy because it seems to me that no one can consistantly manufacture a tube to that accuracy, especially a plastic tube. Even with a drawn metal tube it would be necessary to hone the ID to get that level of accuracy and then it would have to be measured in a temperature controlled room after a time that allows it to come to thermal equilibrium. Considering plastic has several times the thermal expansivity of metal it is near impossible to produce a plastic tube to that accuracy.

I think your engineers should rethink the requirement.

There are two measurements, absolute diameter and out-of-roundness. Which is important? If it is within tolerance for diameter, would it be rejected for out of roundness?

The air gage is the best option but that wouldn't give information about the roundness.

Good Luck.

Thank you for supporting my suggestion. You are right ifyou consider a single gage. For some of the diameters it is possible to use two with an angular shift in between and so get an information about roundness.

Try contacting BetaLaserMike in Dayton OH. They will be able to help you out.

Hello,

Thank you for all the helpful leads. I wanted to clear up too that the area that needs measuring is wire re-enforced which makes tip of the tube more rigid.

Also, the ID is more critical than roundness.

Sue

Hi,

Thank you for the lead on the betalasermike. I have already made contact.

Does anyone have any suggestions for air gage companies? I want to give this technology attention as well since several of you have suggested it.

From what I am learning about air gages...the range is quite limited. For instance, I need the following 6 tubes measured for ID about 0.5" from the tip (see table below). Ideally, it would be great if I could purchase an air gage device that measured the ID of all these tubes such that the range that one device could measure was 0.060" - 0.0183". It seems though that one has to purchase several gages, probably one for each tube listed below?

My biggest concern too with the air gage device is whether it would create a ballooning effect. I have read that air gages are used to measure ID of metal objects which is not hte case here.

I appreciate all the help.

Sue

There really is only one way to go and that's to use air gauging.

resolution and uncertainty can certainly be better than 0.0001".

I've designed gauges to measure jets from 0.0005" up to 1" diameter, with the correctly designed fixturing and adjusted instrument, the cross sectional area can be measured to better than you require.

Hi,

Plz recommend a company. As I mentioned, the tube tip is wire re-enforced but with air gage still need to worry about any ballooning effect...do you have any ideas for companies that deal with PVC. I have found that the air gage companies usually deal with metal, not plastic.

thx.

Sue

Try this company http://www.betalasermike.com/content/view/31/212/lang,en/ They have a system that is used in the medical field that measures the same as what your looking for. The unit measures the ID and OD of plastic tubing for the lines for an "iv". Can't really think of anything more critical then that.

Not sure it will help, but it is possible to measure the diameter of a capillary tube from the height of a water column drawn up the tube. I don't have the formula close to hand, but there is a significant difference depending on diameter, so long as diameter is the only variable (constant temperature, pressure, etc.). A 0.5mm tube will draw a column of about an inch, while a 0.1mm tube will draw more like 6 inches.

Your tolerance block calls out +/- .001" while you stated .0001". If correct how do you hold that in process?

Consider subbing out R&D to a contract CMM shop with the fixturing of your choice. They get it right (for a fee) you copy their method.