drilling 6063 aluminum, burr on breakthrough

I could not get 1/8 x 4 flat in 6061 so they sold me 6063-t6. 3/8" hole at 2037 RPM, 16.26 i/min and I am getting a huge burr on the
backside of the hole. sharpened drill, then changed to new drill, no difference. What's up?
Thank You, Randy
Remove 333 from email address to reply.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Mebbe a 5/16 drill, followed by a 3/8 em. You might also find that with the straight 3/8 drill, yer hole is not perfectly round, either.
The other thing you can do, if possible, is drill stacks, mebbe stacks of 8 or more. This way, only the bottom pc is an issue. And, you'll have a rounder hole with 3/8 drill, and much greater efficiency.
I think your speeds and feeds could be ramped up, as well. Mebbe to 2038 rpm and 16.27 ipm. :) :) Seriously, I think you could easily double both.
Some alum is just crappy and gummy.
--
PV'd



>
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Speed and feeds per ME Consultant program. and I am pilot drilling with a 15/64 so web thinning will not do anything. The 15/64 is used to pilot a slot which is then finished with a 3/16 mill. I seem to recall now that alum tubing drills like this too, all my al tubing is 6063.
Thank You, Randy
Remove 333 from email address to reply.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

centre cutting em won't work ?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thin the web to center.
--


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

us underpacker.........my new word for the day.........a bottom plate
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.