How to punch smaller holes than sheet thickness?

[Tarun Tanwat]

TL;DR Summary

How to punch smaller hole than sheet thickness in stainless steel.

Is it possible to punch 1mm holes in a sheet of SS 316 of thickness 3mm. I have a CNC punching machine but not sure if this would be possible.

 

[Baluncore]

TL;DR Summary: How to punch smaller hole than sheet thickness in stainless steel.
Is it possible to punch 1mm holes in a sheet of SS 316 of thickness 3mm.

Probably not. The hole would not be parallel.

The lowest tech solution would be to drill a few holes with a Cobalt HSS drill.
Second; is to use a solid carbide drill for one hundred holes.
Third would be a water jet, and fourth, a laser.

 

[Ranger Mike]

EDM

 

[Baluncore]

EDM

https://en.wikipedia.org/wiki/Electrical_discharge_machining
I assume that would be Die-Sinking EDM, or Fast Hole Drilling EDM.
DS EDM would be a good solution if the holes were not cylindrical.
FHD EDM will produce only cylindrical holes.
https://en.wikipedia.org/wiki/Electrical_discharge_machining#Fast_hole_drilling_EDM

 

[jrmichler]

TL;DR Summary: How to punch smaller hole than sheet thickness in stainless steel.

Is it possible to punch 1mm holes in a sheet of SS 316 of thickness 3mm.

No. There is a formula in Manufacturing Processes for Engineering Materials by Kalpakjian for estimating the force on a punch:

From the total force, and the cross sectional area of the punch, you can calculate the compressive stress on the punch. Even if the punch had sufficient compressive strength to punch the hole, it would most likely bend sideways and break.