Ball sizing aluminum, what to expect?

I plan to ball size a hole in a ring and want to know how much undersize it needs to be, and how much springback to expect.

Material is 6061, ring has 2" OD with a 7/8" bore.

Any other thoughts or tips on the process would be nice to hear as well.

Thanks, Cole

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No experience of the size you want, but I know small is a bit hit and miss when you're talking sub thousandths - this any help? Bal-tec - Report On Ball Sizing

How much interference? Ball sizing. doesn't remove any stock. If pushes around and redistributes what stock is there so while some minimum stock is necessary,too much may cause a problem.

I've sized a few holes by shoving balls and bullet shaped swages through slightly undersized holes using plenty of lubricant. The pipe fitters and sheet metal workers used for deep drawing a soap and oil mixture.a viscous goo. and their draw tools and swages were hard and mirror finished.

Vague enough?

The guy wants a hole 0.875" + .001". I could bore this, but I thought I may try ball sizing mainly as a way to expand my knowledge and get a great finish.

How much under nominal size would you make the pilot hole? I figured .002-.003" would be adequate. Less interference = less displacement = better chance of landing at the nominal dim, right? I understand it will spring back some, I'm hoping it's less than 0.001".

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I took some notes when I needed to straighten some barrel-shaped short thru-bores (~ .8 deep) in aluminium casting originating from the early 70ies
(according to experts = lousy cast)

Using a Sunnen P-180 was a pita cause the bores were simply too short
to guide the stones and they eventually "hourglassed" the bores

I went over to the press:
I tried it dry = not good
I tried it with honing-oil = even worse

For the lack of an airhammer I used a mallet and a punch.

It works surprisingly easy (no oil)
Just cleaning the rough bores with a ball-hone and using an oversize ball of .008 the barrel-shaped bore came out straight (alltogether 16 bores)
Springback: a tad more than .001

The next 16 bores I utilized WD-40.
It went thru slicker but didǹ t change much.
The surface nice & shiny and most importantly: Straight.
Springback .0012

Some oletimers recommended me an airhammer for not leaving ripples behind but I guess these short bores I worked on prevented ripples, saying that the aluminium could "flex out"

rainer

Awesome, thanks!

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Cole2534 said:

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Click to expand...

They make roller burnishers for this ... not exactly the same but similar and more controllable.

I bought one. Was never happy with the results. Would not recommend it