Bead blasted aluminum rods

[Truckedup]

I saw a set of used aluminum SBC connecting rods that had been bead blasted... I wouldn't think this is a good idea, opinions?

[Dave Koehler]

Won't hurt. Not all alum. rods are shiney BTW.
Caveat: IF they blasted the bores I suspect a coverup or ignorance.

[Truckedup]

Won't hurt. Not all alum. rods are shiney BTW.
Caveat: IF they blasted the bores I suspect a coverup or ignorance.

The bores were blasted also....Even my dumb brain said move on because there's nothing to see here...

[Dave Koehler]

Yup, probably a used set of unknown history that had languished on the shelf too long and got oxidized.
Blast em and sell em scenario.

[Dan Timberlake]

>>IF<< rods were first dye pen inspected and found free of surface "indications" and then blasted with clean glass shot of the right size, at the right pressure, with the right size nozzle the rod surface would have been shot peened to the appropriate Almen intensity and the fatigue life would have been improved.

MIL STD says crack inspections must be done prior to blasting

[Truckedup]

I assume that an aluminum rod at the end of it's expected service life cannot be made good again by any surface treatment ?

[Dan Timberlake]

I assume that an aluminum rod at the end of it's expected service life cannot be made good again by any surface treatment ?

Some aircraft parts get re-peened at each rebuild/inspection. I do not know how their loading compares to con rods (which I pretend is ~ pure tension/compression) .
My assumption is the damage is undone by re-peening. Don't recall if they were ferrous or aluminum

[MadBill]

I assume that an aluminum rod at the end of it's expected service life cannot be made good again by any surface treatment ?

Practically speaking that is true, but there is a proce$$ called HIP (Hot Isostatic Pressing) that could achieve it, maybe combined with re-heat treating and shot peening... http://en.wikipedia.org/wiki/Hot_isostatic_pressing

[BirdMan]

I have used several Howards Rods and they were blasted before machining. M/T rods were smooth.

[Kevin Johnson]

I assume that an aluminum rod at the end of it's expected service life cannot be made good again by any surface treatment ?

Practically speaking that is true, but there is a proce$$ called HIP (Hot Isostatic Pressing) that could achieve it, maybe combined with re-heat treating and shot peening... http://en.wikipedia.org/wiki/Hot_isostatic_pressing

Be careful with HIP and assuming that a part is the same dimensionally before and after. If a void was present in the item since initial manufacturing then HIP could close it but, in so doing, distort the object.

HIP is not intended to correct surface damage or fractures initiating on the surface and, with aluminum alloy parts, surface oxidation of fracture zones could also conceivably prevent peening from correcting or ameliorating such damage.

It might be a good idea to consider HIP for rejuvenation of parts if the process had been used during the original fabrication but combined with careful surface inspection.

Just some things to think about.

Lastly, remember that HIP could very well permanently weld a cap to a beam. Keep them separated.

[stealth]

Also have to wonder what they were blasted with. Depending on material it will get imbedded in the aluminum and dislodges over time finding it's way into oil.

[Dan Timberlake]

MIL spec S13165, now Aerospace spec for shot peening.

http://www.metalimprovement.com/PDF_DOC ... G30-12.pdf

Includes Cleanliness and size of shot, and perhaps most important, Almen intensity for materials of various thicknesses (page 20) using either metallic or non-metallic shot .

[lada ok]

Also have to wonder what they were blasted with. Depending on material it will get imbedded in the aluminum and dislodges over time finding it's way into oil.

When you say bead blasted, down here we automatically assume GLASS bead blasted

NO WAY WOULD YOU EVER EVER EVER do this to the internals of an engine .....
I saw some fella's once that were racing a 1000 Suzuki, after the had destroyed two Yoshimera kits, they then realized that bead blasting the inside of the crankcase to clean it was .....
SHOT PEENING and BEAD BLASTING are poles apart