Drilling Stainless Steel

From:  Kristian Ukkonen [SMTP:kukkonen-at-cc.hut.fi]
Sent:  Friday, May 29, 1998 8:55 PM
To:  Tesla List
Subject:  Re: Drilling Stainless Steel

On Thu, 28 May 1998, Tesla List wrote:

> From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
> Sent:  Thursday, May 28, 1998 4:50 PM
> To:  tesla-at-pupman-dot-com
> Subject:  Drilling Stainless Steel
> Hi All,
>         Like many people, I like to use two large 12 inch salad bowls as a
> top terminal.  For my new one, with built in current sensors, I had to drill
> 5 holes through the bowls.  WOW! was it hard.  The stainless steel in those
> things must be very high in chromium content or something.  I trashed a
> number of nice drill bits.  The titanium nitride bits work for a moment then
> just slide on the surface.  If anybody has any better ways to drill nice
> holes through this stuff, I would love to know about it.

The problem is that stainless steel work-hardens VERY easily. This means
that IF you let the drill bit rotate at the hole without cutting metal
(ie. not enough force to cut), the metal will be very difficult to be
cut/drilled again. So PUSH as hard as you can on the drill and use the
correct RPM. It does help considerably to add cutting oil (or coolant) as
it will both help the drill cutting edge (forms a film there) and cool the
system. Use a drill with correct cutting angles as well, if possible. 

That is for the "usual" austenitic stainless steels (aisi316 etc.). 
Special alloys can be next-to-impossible to cut especially after they 
have been heat-treated.. But I think the bowls are the cheapest
alloy they could use so it should not be too hard to drill.

  Kristian Ukkonen.

| Kristian Ukkonen       |  Do as thou wilt shall be the whole of the law |
| kukkonen-at-alpha.hut.fi  |_____  Chance favours the prepared mind  |-------
| http://www.hut.fi/~kukkonen |  Fear is the mind-killer  |---------
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