drilling stainless!!/ melting drill bit

I decided to drill a 5/16" hole in the end of a 5/8" piece of round
stock (SS 404 i think)....
it all started well , I was going at a relatively slow pace . the chips
off the drill bit looked ok
after i got 1/4" in i got a little smoke but i didnt think too much
about it.. but the rate of drilling slowed down a bit. THEN i looked
down and the drill bit was GLOWING BRIGHTLY! it melted!!!
I expected stainless to be a bit tougher than regular steel but not like
this!
what did i do wrong?
rtv
Reply to
rtv
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Too high a spindle rpm. Stainless drills best at very low rpm w/heavy feed. JR Dweller in the cellar
rtv wrote: > > I decided to drill a 5/16" hole in the end of a 5/8" piece of round > stock (SS 404 i think).... > it all started well , I was going at a relatively slow pace . the chips > off the drill bit looked ok > after i got 1/4" in i got a little smoke but i didnt think too much > about it.. but the rate of drilling slowed down a bit. THEN i looked > down and the drill bit was GLOWING BRIGHTLY! it melted!!! > I expected stainless to be a bit tougher than regular steel but not like > this! > what did i do wrong? > rtv
Reply to
JR North
i'm sorry i think i meant 304 stainless rtv
Reply to
rtv
On Tue, 09 Dec 2003 20:03:01 -0500, rtv put forth the notion that...
Gotta go slow with stainless. The hotter it gets, the tougher it gets to cut. It'll burn up HSS tooling pretty easily, even when the work piece gets red hot.
Reply to
Checkmate
I've been told some grades of SS work harden significantly if the drill dwells in the hole, forming an hardened button that can deflect the drill off axis. I have not experienced it firsthand, but the same source tells me the solution is to use drills that can take the heat and apply steady feed (if pauses are necessary, remove feed pressure completely to keep the drill tip from working the material).
StaticsJason
Reply to
Statics
--Whatcha using for a lubricant?
Reply to
steamer
Internet and trade shows only. Phil
Reply to
Phil Ordway
Slow and a small drill first.
Larger drills don't drill a center - it spins in the metal. The cutting force isn't high at the center with the radius short.
Work up through drills.
Might have to use carbide to drill a pilot now. May have to heat treat to relax it.
Martin
Reply to
Eastburn

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