Micro Hole Boring

Gun drilling only goes down to about a few milimetres diameter.

How about looking at surgical instrument manufacturers who make hypodermic needles?

I've done a few jobs for medical companies and they seem to be able to get long tubes with tiny holes for needles - wouldn't something like that do for you and then you can implant the needle within your part?

Just a thought.

Implant is good Idea, But question is how they produce 1mm hole in big block, I believe poster is more interested in technology than doing it once by a quik and dirty method.

Thanks for suggestion, needle technology would be last resort, and I'm specifically interested in 5Cr 0.5Mo steel which would be a problem.

I'd check out companies who do EDM! (Electrical discharge machining)

Electrode deflection is a biggest concern.

1mm dia 120mm lenght.

http://www.sme.org/cgi-bin/find-articles.pl?&01fe0088&ME&20010206&&SME&#article

http://www.osg-uk.com/files/TDXL%20[UK].pdf

A Swiss company, SARIX, makes EDM capable of that size. However, I can't recall what depth limitations you might run into. Distributor in Midwest US .

Look for a wire edm company. Self starting pilot holes down to .015 are doable. then wire capture and clean up within tolerance, if they know what they are doing. Drilling is doable but there would be a number of pieces falling out due to drill breakage. A swiss style machine can do this if the piece is round stock. Peck depth of .030 will get there eventually....

Redesign is also a good option. Can a portion of the hole depth be larger? Can the same be done another way.

Is that pilot hole of 0.015 is in mm or inches? Can you please elaborate more how it is produced in thick blocks?

Thank you in advance.

As I understand ECM and CM is best suited for thinn sheet metal parts.I doubt it can be a good process for thick blocks.

In ECM process one can not control current flow in desired direction likeiwse in EDM. and that creats the problem of overcut.So as one go in depth, hole will keep on increasing in diameter, and bore will be tappered in shape.

Dear rakesh semval,

you mixed up the ECM and EDM taper of holes.

In EDM you have electrode wear that will produce near 1:50 taper if operator and machine is ik.

In ECM there is no electrode wear and if the outside of the electrode tube is electrically isolating then there is nearly ideal straightness . Diameter is not too tight to nominal, +- 0.05mm is normal, +- 0.01 mm can be achieved.

So I insisted in my above post to have the electrode insulated on the outside!

RHABE

Does anyone know of a company (UK prefered) capable of boring a 1 mm dia hole of length ~120 mm in 5Cr steel.

If there is any scope for splitting the part through the hole location, or alternatively making it from laminations clamped together then you can easily make a hole of almostany axial and cross sectional shape by electro machining a track in one or both laminations. This technique offers some interesting possibilities in that you can easily introduce byepasses, filters and other geometrical features that would not be possible by a conventional machining technique

This is an interesting thought and I can see the possibilities, however I need to be able to clamp the two halfs together again perfectly so that they will withstand ~500psi pressure at 400°C with no leaks. Do you think this can be done?

Hi,

this was a really good idea posted by CADMAN.

If you can add some 1 to 2% of carbon to your chromium-steel then this splitting and rejoining technique will be possible. I saw this many years ago.

Another possibility may be to take a suitable tube and braze this into a hole of significantly higher diameter.

These tubes are drawn similar to wire-drawing so nearly any diameter is available. Also seamless thick-walled tubes are available that are cold worked by NC-rolling on mandrels.

RHABE

------will withstand ~500psi pressure at 400°C with no leaks. Do you think this can be done?

This order of pressure and temperature is experienced in auto engine cylinder heads and leakage is prevented by gaskets with the help of the cylinder head clamp bolts.One suggestion is to use a copper gasket of say 2mm thickness and to etch the 'hole' on the face of the gasket and then to clamp it with bolts able to provide the required clamp force. Without knowing the geometry of the application it is difficult to comment on wether or not this is feasible

Laser cutting may be viable.

Hello Ron55:

CADMAN's idea sounds interesting.

Can you tell me if this is a 'one off' or will this need to be done to each of several thousand pieces?

I would have thought an easier way was to thread the whole and screw in a needle valve.

By the way, what is this tiny hole for?

This just a few off, (10's) but definitely needs to be a narrow , smooth bore hole in P5 pipe alloy steel, unfortunately its a confidential application for my company so can't really say much more of the detail. I hadn't realised it was going to be as much of a technical challenge as it is turning out to be.

Hello Ron55:

Oh I see..............SO WHAT YOU MAKING THEN?.........Sorry, had to through what I call a joke in there.

Without saying, is it a breather hole? I suppose a tungsten carbide drill that size with little pressure on it and given time to let it do it's job, would break?.........Looks like, as has been said, you may have to groove the two halves.

It really depends on the shape of the thing you have to have the 1mm hole in, as to how difficult lining the groves up, is?

Good luck.

Hello this is a company that can help you, maybe your Hole is to big for this company

good look

L.A.

Microcut Ltd
Rolliweg 21/P.O.Box 448
CH-2543 Lengnau BE
Switzerland

Phone: +41 (0)32 654 15 15
Fax: +41 (0)32 654 15 16

E-Mail: info@microcut.ch

www.microcut.ch

Yes it can be done with EDM and a company in the UK does it. I don't remember their name and it was in proprietary information 6- 7 years ago so I don't have the memory to tell you who it was and I'm probably still legally bound on the how.

Sorry I'm not of more help but you are on the right track.

Brad

We used to drill holes of about those dimensions in quartz. We used a diamond core drill in a rotary ultrasonic impact grinder. The particles removed are basically powder and can be continuously flushed out with fluid. Therefore there is no clogging as there would be with a cutting tool. The process is a miniaturized version of a rotary hammer drill.