Hi,

   I need to to get a positive feature which is 100um diameter and 500um
long (a very small rod) with milling machine. I can use aluminum or steel.
I wonder if it is possible? If so  which material is better? I think aluminum
is easy to cut but may be  too flexible for a feature like this. Any 
suggestions on the cutting parameters are highly apprecicated. 

    Thanks a lot!

    Regards,
    
    Tao

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Request for Question Clarification by redhoss-ga on 23 Mar 2006 15:44 PST

Why can't you use wire.

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Clarification of Question by taosong-ga on 24 Mar 2006 06:43 PST

This is for a microarray kind of applications. For one or two parts
use wire is OK. But for something like microarray using wire will be
very inconvenient and need careful alignment.

I am unsure that this feature could be machined using a traditional
mill. Even if it were capable of the tolerance you require, the force
applied by the bit may be enough to exceed your materials yield
strength. I would suggest investigating laser micromilling,
electrochemical micromachining, and micro EDM--perhaps redhoss knows
of some other high tolerance subtractive machining alternatives.

Here's some links about the processes:

Laser:
http://www.oxfordlasers.com/micromachining/how_it_works.htm
Electrochemical:
http://www.tu-darmstadt.de/fb/ch/Fachgebiete/PC/AKSchuster/micromach.htm
EDM:
http://www.mech.kuleuven.be/micro/topics/edm/

All these methods can be used with steel and other materials, and
should have more than the level of tolerance for your application. One
Caveat with EDM is often an orange peel surface finish due to the
process, but micro EDM shouldn't present that problem--or at least on
a negligible scale.