Subject: Re: Al weld to endmill - help.

From: Mike Rehmus <[email-masked]>
Date: 12 Jul 1995 17:13:32 GMT

You don't say what alloy of aluminum.  Are the two sheets different?

I'd guess that you might have a 1/16" sheet of 6061 which is going to glue itself to 
a dry tool bit.  Your 1/8" sheet may be some other alloy.

Try to use just a little bit of the original Tap Magic for aluminum on the mill.  
Apply it with an acid brush or equivalent.

Otherwise, you will get very tired of breaking off the sticky bits from the 
end-mill.

Best,

Mike Rehmus

---

From: [email-masked]
Date: Thu, 13 Jul 1995 03:58:18 GMT

Tad B Artis ([email-masked]) wrote:

: : I'm cutting slots in 1/16" Aluminum sheet with a 1/8" TiN 2-flute Putnam 
: : HSS endmill on a Sherline CNC.  I'm cutting dry at .0005 ipt & 2000rpm (that's
: : the best Sherline can do)

: : The chips aren't clearing very well and are welding to the endmill and coming
: : all the way back around to make a mess.  It seems to happen even if I try
: : to take the edge off the slot to clean it up.

  Try a standard HSS end mill.  I have heard the TiN mills have problems 	
with Al.  For light use the HSS is as good IMHO.

---

From: [email-masked] (Russ Kepler)
Date: Thu, 13 Jul 1995 02:35:00 GMT

In article <[email-masked]>,
Tad B Artis <[email-masked]> wrote:
>Thanks.  I'm not sophisticated enough to know how to tell what type.  The
>1/16" is an electronics enclosure chassis (not cast) & the 1/8" is 
>stock from the local hardware store.  I'll try the Tap Magic; although I
>was hoping to go dry.  Any other thoughts would be appreciated.

You could try a high-shear carbide - that might handle the sticky Al
problem.  The only problem is that they're about $10 from MSC (page
465).

-- 
Russ Kepler posting from home  [email-masked]

                      Please don't feed the Engineers

---

From: [email-masked] (Tad B Artis)
Date: Wed, 12 Jul 1995 18:45:59 GMT

Mike Rehmus ([email-masked]) wrote:
: You don't say what alloy of aluminum.  Are the two sheets different?

: I'd guess that you might have a 1/16" sheet of 6061 which is going to glue itself to 
: a dry tool bit.  Your 1/8" sheet may be some other alloy.

: Try to use just a little bit of the original Tap Magic for aluminum on the mill.  
: Apply it with an acid brush or equivalent.

: Otherwise, you will get very tired of breaking off the sticky bits from the 
: end-mill.

: Best,

: Mike Rehmus

---

From: [email-masked] (Doug White)
Date: Thu, 13 Jul 95 01:05:04 GMT

In article <[email-masked]>,
   [email-masked] (Tad B Artis) wrote:
<Thanks.  I'm not sophisticated enough to know how to tell what type.  
The
<1/16" is an electronics enclosure chassis (not cast) & the 1/8" is 
<stock from the local hardware store.  I'll try the Tap Magic; although I
<was hoping to go dry.  Any other thoughts would be appreciated.
<
<Mike Rehmus ([email-masked]) wrote:
<: You don't say what alloy of aluminum.  Are the two sheets different?
<
<: I'd guess that you might have a 1/16" sheet of 6061 which is going to 
glue itself to 
<: a dry tool bit.  Your 1/8" sheet may be some other alloy.
<
Actually, 6061-T6 is pretty good stuff for machining.  Unfortunately, 
they don't use it for electronics boxes because it isn't soft enough to 
bend nicely.  Most electronics chassis are made out of a 50XX type 
aluminum, and the stuff is horrid to machine dry (as you have 
discovered).  Although it is going to be a bit messier, you don't have to 
drown everything in cutting fluid, you just have to keep the flutes of 
the mill wet enough that the aluminum doesn't stick.  A drop or two per 
slot should be sufficient.  I use 'Mr. Cool Tool', but there are all 
sorts of good lubes on the market.  I bought a pint 10 years ago, and I'm 
just about ready to buy another.  I use a disposable 'acid brush' to 
apply it to small drill bits and end mills.  

Doug White

---

From: "james a. whitten" <[email-masked]>
Date: Wed, 12 Jul 1995 21:27:38 -0400

If you can't get a hold of Tap Magic or Cool Tool try dabbing some 
mineral sprits or even Diesel Fuel (if You can stand the smell) on the 
endmill. I don't remember the spindle speed you gave but sometimes if you 
slow it down that helps. Cutting Oil dabbed on with a brush helps too (MY 
choice)

	"BIG" JIM

---

From: [email-masked] (Ken Christianson)
Date: 13 Jul 1995 22:50:31 GMT

In <[email-masked]> [email-masked] (Jonathan
M. Elson) writes: 
>: New guy has following problem:
>
>: I'm cutting slots in 1/16" Aluminum sheet with a 1/8" TiN 2-flute
Putnam 
>: HSS endmill on a Sherline CNC.  I'm cutting dry at .0005 ipt &
2000rpm (that's
>: the best Sherline can do)
>
>: The chips aren't clearing very well and are welding to the endmill
and coming
>: all the way back around to make a mess.  It seems to happen even if
I try
>: to take the edge off the slot to clean it up.
>
>: Strange thing is:  It works fine with 1/8" Aluminum sheet (different
source
>: & more rigid jig).
>
>: I want to continue to cut dry.  Why the discrepancy & what to do?
>
>Forget cutting nearly any metal dry!  Brass is not too bad, actually. 
The
>softer (less alloying added) aluminum is, the harder it is to machine,
but
>the easier it is to bend.  Punching works fine either way.  Since
electronic
>chassis are made by punching and then bending, elemental aluminum is
often
>used.  A very soft metal, it tears and cold-flows, rather than
cutting,
>producing great heat, which further softens it.  A cutting fluid
prevents
>the sticking, aids heat removal from the micro area around the cutting
edge,
>and helps the tool rotation to fling the chips away.  I find using the

>largest cutter at the highest reasonable speed helps chip removal.  At
least
>a thin film of oil on the tool and the workpiece is ABSOLUTELY
NECESSARY
>for the softer aluminum alloys.  Even using the sharpest tools on
unalloyed
>Aluminum sheet, and using liberal amounts of cutting oil, you will
have much
>trouble.  I am referring to ready-made boxes and chassis like Bud, 
>LMB/Heeger, and others.  Very fine cuts at slow feed rates (sometimes
as fine
>as .010 depth cuts) at high spindle speeds (1000 RPM for 3/8" tools,
>750 RPM for 1/2" tools) is my recommendation.  If using sheet stock, I
>recommend never using unalloyed Al, but using a harder alloy.  You
will
>still need lubrication, however, or even a TiN coated tool will have
the TiN
>worn off in ONE AFTERNOON!
>
>I speak from the experience of machining very frequently in thin
aluminum
>sheet for making instrument panels, etc. for nearly 20 years.
>

-----> you also might consider using a tool like a "chassis nibbler"
instead of a mill.  Granted this might call for some follow up with a
file or Dremel which might not be the best if this is for a large
production run, but if you were doing large production  you would
probably be using a custom or ready made chassis punch.
       By the way, Dremel has a great attachment called a Routing
fixture and with that and a simple jig  you could clean up the edges
very efficiently.
    Good luck

---

From: [email-masked] (Jonathan M. Elson)
Date: 13 Jul 1995 20:56:35 GMT

: I'm cutting slots in 1/16" Aluminum sheet with a 1/8" TiN 2-flute Putnam 
: HSS endmill on a Sherline CNC.  I'm cutting dry at .0005 ipt & 2000rpm (that's
: the best Sherline can do)

: The chips aren't clearing very well and are welding to the endmill and coming
: all the way back around to make a mess.  It seems to happen even if I try
: to take the edge off the slot to clean it up.

: Strange thing is:  It works fine with 1/8" Aluminum sheet (different source
: & more rigid jig).

Forget cutting nearly any metal dry!  Brass is not too bad, actually.  The
softer (less alloying added) aluminum is, the harder it is to machine, but
the easier it is to bend.  Punching works fine either way.  Since electronic
chassis are made by punching and then bending, elemental aluminum is often
used.  A very soft metal, it tears and cold-flows, rather than cutting,
producing great heat, which further softens it.  A cutting fluid prevents
the sticking, aids heat removal from the micro area around the cutting edge,
and helps the tool rotation to fling the chips away.  I find using the 
largest cutter at the highest reasonable speed helps chip removal.  At least
a thin film of oil on the tool and the workpiece is ABSOLUTELY NECESSARY
for the softer aluminum alloys.  Even using the sharpest tools on unalloyed
Aluminum sheet, and using liberal amounts of cutting oil, you will have much
trouble.  I am referring to ready-made boxes and chassis like Bud, 
LMB/Heeger, and others.  Very fine cuts at slow feed rates (sometimes as fine
as .010 depth cuts) at high spindle speeds (1000 RPM for 3/8" tools,
750 RPM for 1/2" tools) is my recommendation.  If using sheet stock, I
recommend never using unalloyed Al, but using a harder alloy.  You will
still need lubrication, however, or even a TiN coated tool will have the TiN
worn off in ONE AFTERNOON!

I speak from the experience of machining very frequently in thin aluminum
sheet for making instrument panels, etc. for nearly 20 years.

---

From: [email-masked] (Dan Wold)
Date: 14 Jul 1995 02:51:06 -0400

james a. whitten ([email-masked]) wrote:
: If you can't get a hold of Tap Magic or Cool Tool try dabbing some 
: mineral sprits or even Diesel Fuel (if You can stand the smell) on the 
: endmill. I don't remember the spindle speed you gave but sometimes if you 
: slow it down that helps. Cutting Oil dabbed on with a brush helps too (MY 
: choice)

: 	"BIG" JIM

Try "AlumaTap" cutting fluid. That's what I use on aluminum. It's clear and
has a nice odor. 

-Dan
-- 
[email-masked]
Daniel Wold                               239 City Island Ave,Bronx,NY,10464
finger [email-masked]
"The earth is but one country, and mankind its citizens." -- Baha'u'llah

---

From: [email-masked] (Mark McDade x36841)
Date: Sat, 15 Jul 1995 03:45:17 GMT

Jonathan M. Elson ([email-masked]) wrote:
: Tad B Artis ([email-masked]) wrote:
: : New guy has following problem:

: : Strange thing is:  It works fine with 1/8" Aluminum sheet (different source
: : & more rigid jig).

: : I want to continue to cut dry.  Why the discrepancy & what to do?

: Forget cutting nearly any metal dry!  Brass is not too bad, actually.  The

. . . 

I would say that if it absolutely has to be dry for some reason, at
least direct a stream of compressed air at the cutter.  I've found
that WD-40 is a pretty good aluminum cutting fluid and is packaged
for easy use with a small mill like the Sherline.  The other thing
that helps is to make the basic cut in the usual way, then return
the cutter back along the same path (in the "climb milling" direction)
without advancing the table or column - it will clean up the cut
somewhat.

Something else to check is that fewer flutes are better - if you use
a two flute mill instead of three or four, aluminum will probably
react better.

Mark McDade

[email-masked]