Teflon Machining

[Munzter]

I am trying to machine small OD holes (0.02") into teflon to be used spraying liquids such that the liquids come out parallel to one another but am having trouble with this due to the burs that are created at the edge of the hole. Is there any way to remove these burs during the machining process?

 

[btrueblood]

How thick is the teflon? Are you drilling the holes now?

 

[Munzter]

About 7-8mm thick, about the length of my drill bit. I have tried multiple times but I just got done drilling another set and it still has burs. I am using a drill press with a 0.02" drill bit. I initially go in with water to keep the drill bit cool, but once the hole is established I do multiple passes up and down with out water for increased friction and this ends up taking about 15 minutes or more per hole. The burs cannot be seen by the naked eye, but I have used a microscope to look at the holes and under the microscope, the entrance hole has burs while the exit hole does not.

 

[btrueblood]

So the entrance burr (I assum you are drilling in same direction as the flow is going to go) is giving you trouble? Can you not just chamfer the inlet edge to cut the burr?

You might talk to a water-jet house and ask if they can bore these holes.

 

[patprimmer]

Freeze it in liquid nitrogen to make the PTFE hard.

Regards

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[Munzter]

If I were to freeze it in liquid nitrogen, wouldn't it thaw before I had a chance to drill the holes? That's an interesting idea I may try since we do have liquid nitrogen on hand.

 

[Compositepro]

You migh consider making a compression mold for your part that you cold put in an arbor press. Drill the hole and insert a pin and squeeze the part so it has smooth molded surfaces. Teflon is dificult drill cleanly.

 

[Demon3]

Feezing is a nice idea. What happens when you drill the holes starting at the opposite side? So you start drilling at the side where the flow will emerge. That might give you a burr free hole on that side. Or you could lightly use a countersink drill to remove the burrs.


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