On Wed, 18 Jan 2006 05:15:15 GMT, "SPI01" wrote:

"Polymer Man" wrote in message
roups.com...
When turning aluminum parts that have been welded, I've never been able
to get a good finish in the heat effected zone near the weld. I've
tried different carbide inserts and even ground HSS into a very sharp
tool with a lot of rake, almost like a wood cutting tool to no avail.
I've tried different feeds and speeds, different water soluble oils,
TapMagic and even moly-dee but the aluminum is soft and chunky and
won't turn smooth. Is their a magic bullet I'm missing?


It sounds like 6061. You have lost the temper in the alloy. This problem
can be resolved only by post heat treatment to bring it back up to a T6 or
other desired temper. The heat affected zone has also lost a significant
amount of strenght due to the fact that it is effectively annealed. Most
applications can tolerate this loss in strength but it may be an issue
depending on the use. as far as machining goes diamond tooling at very high
speed can leave a good finish in this situation, but must be run at very
high speeds to be effective in finishing the gummy area. Good Luck!!
-Dennis

Perhaps an alteration in the welding process or filler?
--
Cliff