Drilling Stainless

When drilling the 300 series stainless steels one must be aware that they will work harden. They will harden ahead of the cutting lip, and then the drill will skate and become ruined. To drill 300 Stainless, first you need a good quality, sharp drill bit. This pretty much excludes brill bits from HF. Second one needs the right speed and the right feed. Speed is the rate that the cutting lip moves across the metal and the feed is the rate the cutting lip is advanced into the metal usually noted in thousandths/revolution. For the 300 series stainless steel since they work harden, never let the feed relax. If you need to withdraw the bit to clear chips go from full feed and speed to full speed and reverse as instantly as possible.

Another tip is to either avoid center punching or use the lightest center punch as possible as the punch will work harden the metal and make entry of the drill difficult. Some use a 3 sided very slender punch to make a decent mark and make drill entry easier.

A very good field expedient lubricant for low production rate drilling is to use Crisco. Dip the cold bit in start drilling. Re-dip often to keep the lube where it should be. Never ever lube a very hot drill bit when drilling any material as this causes small cracks the cause bit failure.

The Crisco works well for punching stainless sheet cold as well. So if you are using a hand punch or bench punch on stainless sheet try a little Crisco for better punch life and easier punching.

As always Butter flavor is better "Cause it tastes better" 

Written by Jeff Reinhardt