Cleaning up a reamed hole?

[Boelkowj]

Can anyone advise me how I should clean up a 5/16th reamed aluminum hole to
eliminate stress fractures. Is the process called "burnishing" and how is it
done? Will fine grade sandpaper work. This is an important wing fitting.
Thanks.

Larry

[Kyle Boatright]

"Boelkowj" > wrote in message
...
> Can anyone advise me how I should clean up a 5/16th reamed aluminum hole
to
> eliminate stress fractures. Is the process called "burnishing" and how is
it
> done? Will fine grade sandpaper work. This is an important wing fitting.
> Thanks.
>
> Larry

Other than deburring the edges, I wouldn't do any further work to a reamed
hole. It should be very smooth in the first place.

KB

[Richard Lamb]

Kyle Boatright wrote:
>
> "Boelkowj" > wrote in message
> ...
> > Can anyone advise me how I should clean up a 5/16th reamed aluminum hole
> to
> > eliminate stress fractures. Is the process called "burnishing" and how is
> it
> > done? Will fine grade sandpaper work. This is an important wing fitting.
> > Thanks.
> >
> > Larry
>
> Other than deburring the edges, I wouldn't do any further work to a reamed
> hole. It should be very smooth in the first place.
>
> KB

Yeah. If you are at final size hole and have detectable cracks,
Doitover....

[Boelkowj]

KB: I haven't done the job yet. But thought burnishing/cleaning up the hole was
SOP even if the hole looked smooth and almost perfect.

Larry

[Veeduber]

> But thought burnishing/cleaning up the hole was
>SOP even if the hole looked smooth and almost perfect.

--------------------------------------------------

Normally, reaming is the final step in preparing a hole to accept a fastener.
Any chamfering is done prior to the final reaming.

Assuming there are no visually apparent flaws, with parallel-sided holes the
quality of any hole is relative to the fit of the fastener. There are four
general catagories of fit: Free, light press, driven, and shrunk.

'Burnishing' has several interpretations with regard to holes and varies
according to the application. At one time it was common practice to knurl an
oversized hole then swage it back to spec using a hardened dowel. But such
practices are not used in aircraft.

-R.S.Hoover

[Lennie the Lurker]

(Boelkowj) wrote in message >...
> KB: I haven't done the job yet. But thought burnishing/cleaning up the hole was
> SOP even if the hole looked smooth and almost perfect.
>
> Larry

Reaming is a way of sizing a hole, and reamed finishes often are not
nice. Reaming aluminum is difficult to hold any kind of finish unless
the hole is within .001"-.003" of finish size to begin with.
Burninshing is done most often by forcing a hardened ball through the
hole, the hole being left .0005" or so undersize. Burnishing does NOT
remove stress risers, it only covers them up so you can't see them.
If there is a stress riser present, it is still there after
burnishing.