Better Surface Finish

[Travis2282]

I am currently making some 6061 aluminum parts, I have a hole that is .625 dia. and it requires a 32 micron finish. I reamed this hole out and thought it had an excellent finish, but it was measured at 50 microns. Any suggestions on how to get a better surface finish. I have to hold a .0005 tolerance.

[MotorCityMinion]

Put a small radius on the reamer leads and use Tap majic for aluminum, works great. Boring bar with a larger nose radius might work also.

[Colin Gilchrist]

What Speeds/Feeds are you running?

 

Try dropping your RPM a little bit and cutting your feedrate in half. Also, make sure you use the "feed out" bore cycle so that your tool isn't trying to rapid out of the hole.

[Travis2282]

I had used 300 rpm with 3ipm feed. dont care if it took longer just needed good finish.

[mchin-pilot]

Roller Burnishing

[dforsythe]

+1 for the roller burnishing tool. the work great in ss also.

[Travis2282]

Never heard of these, Any certain brands you would reccomend?

[Colin Gilchrist]

Cogsdill.

 

http://www.cogsdill.com/pdf/USCatalogs/Com...hingCatalog.pdf

 

Look at page 8 of this catalog.

[Kevangel]

I have also burnished aluminun castings to size (.0001 in.) using a drill blank polished to the size that works and then used alumicut to keep from galling..I bought several reamers to get just the right size with minmal stock...some experimentation and then did several hundred holes..toolmaker approach waaay back when...

.1245 dia. hole

[Trevor Bailey]

thicker oil and leave more on the walls for reamer to remove.

[Dave.L]

You don't need to burnish to get a 32. burnishing will give you an 8 or less. You could easily circular mill and get a 32 and hold that tolerance. Your RPM is way to slow. Speed up the RPM and slow the feed.

 

For AL you should be 1000 SFM min.

[Travis2282]

The hole i am reaming is 4 in. long. I roughed it out with a emill. So i figured reaming would get me within spec easier.