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Shot Peening

General engine tech -- Drag Racing to Circle Track

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Malvn
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Shot Peening

Post by Malvn »

Are most or some shops still offer Shot Peening ?? I always thought this was worth Doing and the extra money to have it done. Whats the General
Opinion of Other"s here on Shot Peening ?? :)

I added a link for some that might not know of Shot Peening .

https://www.wheelabratorgroup.com/en-us ... ot-peening
Malvin


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PackardV8
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Re: Shot Peening

Post by PackardV8 »

We have two shot blast cabinets and over the years have found the general use machines offer very little benefit to changing component characteristics. This requires a specialized cabinet with carefully controlled shot size, impeller speed, component rotation and costs a bunch to do it to best effect.

OTOH, a big blast cabinet is magic in cleaning the crusty, rusty Studebaker and Packard cores we deal with. It definitely requires careful washing, inspection, brushing of all passages. Just a few stray shot can play hell with the otherwise precise build.
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Re: Shot Peening

Post by BCjohnny »

Are most or some shops still offer Shot Peening ??

To my knowledge 'most' shops have never offered shot peening, at least not in the context you're referencing anyway, although some more specialized ones might

'Most' shops use it as simply a 'cleaning stage', so there is little attempt to control the finer points of the 'conditioning process' which is the critical factor here

Having said that, anyone who has a well maintained airless paddle round steel shot system will be able to impart a degree of compressive stress to a component without even thinking about it, but it's not going to be to any MIL spec ..... myself, and I guess many others, do it all the time

And then you have the common 'guy stands in front of a box and pokes his arms in' compressed air manual cabinets ....... virtually none of them IMO are set up to apply a true conditioned compressive stress to the part, as they mostly use 'abrasive' media, with the exception of a well maintained glass bead peening system ...... and they're not exactly common as the natural temptation for the uninitiated is to turn up the pressure to get them to 'work' faster, destroying the critical media in the process #-o

It's a bit of a rarity to find anywhere that will have a cabinet set up to, say apply cast steel S230 shot, at the right pressure (and have a compressor to maintain it) and have complete faith in what they're achieving

So if you want a certified process, you usually have to go to a shop that offers it, usually aviation based or the like ....... and get your cheque book out
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon
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Re: Shot Peening

Post by mt-engines »

BCjohnny wrote: Mon Nov 16, 2020 3:27 am
Are most or some shops still offer Shot Peening ??
So if you want a certified process, you usually have to go to a shop that offers it, usually aviation based or the like ....... and get your cheque book out
Or become buddies with the owner of a foundry or the operator of a wheelabrater ;)
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Re: Shot Peening

Post by PackardV8 »

mt-engines wrote: Mon Nov 16, 2020 3:45 am
BCjohnny wrote: Mon Nov 16, 2020 3:27 am
Are most or some shops still offer Shot Peening ??
So if you want a certified process, you usually have to go to a shop that offers it, usually aviation based or the like ....... and get your cheque book out
Or become buddies with the owner of a foundry or the operator of a wheelabrater ;)
I've worked in a steel foundry as well as the aforementioned engine shop. Neither has anything which will do true "shot peening" with the quality control to evenly process parts. They're just aggressive abrasive cleaners.
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David Redszus
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Re: Shot Peening

Post by David Redszus »

Machining operations impart tensile stresses to the surface of machined parts.
Tensile stress lowers the fatigue life and fracture strength of the material.

Stress relieving of tensile stress will improve service life. Shot peening is one method used to convert
tensile surface stress to compressive surface stress.

Steel or cast iron balls, of specified size, are impacted by air or mechanical force, against the
material surface to impart compressive surface stress.

for steel
Dia (in)....PSI.....+Stress (KSI)
0.125......90......+60
0.067......60......+30
0.023......50......+10
0.011......30......+5

A similar process can be used for aluminum using fresh round glass beads, only once.
Once used they become fractured with sharp edges which defeats the purpose.
Malvn
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Re: Shot Peening

Post by Malvn »

BCjohnny wrote
Most' shops use it as simply a 'cleaning stage',


It should be Clean the parts first before you have the Controlled Shot peening Done. :)

I guess I am lucky The Shop I have used in the pass 30-40 years uses a A controlled shot peening cabinet with consistency Air pressure for the Parts I
want done . :) I do know that Shot peening is used in the aircraft industry . :) It would be a big waste to just use shot peening for just cleaning
or maybe those that do that just really do not care. :)
Malvin


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Re: Shot Peening

Post by PackardV8 »

Maybe, share with us the types of parts you have shot peened and how you evaluate the benefits thereof?
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Re: Shot Peening

Post by mt-engines »

PackardV8 wrote: Mon Nov 16, 2020 12:45 pm
mt-engines wrote: Mon Nov 16, 2020 3:45 am
BCjohnny wrote: Mon Nov 16, 2020 3:27 am

So if you want a certified process, you usually have to go to a shop that offers it, usually aviation based or the like ....... and get your cheque book out
Or become buddies with the owner of a foundry or the operator of a wheelabrater ;)
I've worked in a steel foundry as well as the aforementioned engine shop. Neither has anything which will do true "shot peening" with the quality control to evenly process parts. They're just aggressive abrasive cleaners.
The two foundrys i worked in we had 5 different types of wheelabrators and multiples of the same, in house heat treating facility, cnc machining centers, full pattern shop, a full laboratory for inspection with x-ray machines. Heck one had their own cement plant. They made their own welding rod for certain military castings. Mostly military contracts is what they did, but did crankcases and cylinders for Lycoming, Continental, Harley Davidson, S&S, Honda John Deere Did Transmission Cases and torque converters for Allison, Jerico. They had 4 Low pressure molds that did Raytheon jobs at all times. Anyways, i can assure you that it wasn't just to make the castings look pretty, most off the castings looked good even before grinding. and even after heat treat. All castings went through at least one. some went through multiple. If you find a foundry that does heat treat and surface prep in house. They can peen it for you. Some parts we did had fixtures and a load they had to apply to the castings during the process, specific time and shot pressure.
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Re: Shot Peening

Post by mt-engines »

PackardV8 wrote: Mon Nov 16, 2020 6:30 pm Maybe, share with us the types of parts you have shot peened and how you evaluate the benefits thereof?
ever used a PSI RML sping vs the non RML of the same part number? The data doesnt lie. The nano peened springs lasted considerably longer. its not just a surface prep.
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Re: Shot Peening

Post by Malvn »

I have Had Crankshaft"s Fillets done , Connecting rods , Valve springs , Rocker arms, all done so Those parts would last under Higher Horsepower
application's . :)

https://www.shotpeener.com/library/pdf/1985003.pdf
Malvin


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Re: Shot Peening

Post by digger »

shot peening is a well proven process but like everything it comes down to the specification and process.
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Re: Shot Peening

Post by PSA »

Isn't most new rods and cranks delivered that way today?
I've seen some that also have the option for ceramic peening (CP offers it for the pins).
http://www.wpctreatment.com/about.htm
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Re: Shot Peening

Post by autogear »

My retired GM at Auto Gear, was the Plant Engineer who oversaw the Wheel Abrators at New Process Gear /New Venture Gear/Magna. The different types of media you can use and how much compression you get, along with trying to keep the machines from devouring themselves? Its a completely different process than what Cooter is selling to his local fans for souping up their restored GM "pink" rods.
I got the distinct impression that, given the sheer array of media, and notebooks Matt kept on adjustments to the machines; there were few people who were doing it the correct way.
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Re: Shot Peening

Post by PackardV8 »

autogear wrote: Tue Nov 17, 2020 9:44 am My retired GM at Auto Gear, was the Plant Engineer who oversaw the Wheel Abrators at New Process Gear /New Venture Gear/Magna. The different types of media you can use and how much compression you get, along with trying to keep the machines from devouring themselves? Its a completely different process than what Cooter is selling to his local fans for souping up their restored GM "pink" rods.
I got the distinct impression that, given the sheer array of media, and notebooks Matt kept on adjustments to the machines; there were few people who were doing it the correct way.
X2 - it's not a walk-in, drop off your parts, pick them up process. Yes, as noted with valve springs, there is a performance/durability benefit and that's why there is a considerable price difference.
Jack Vines
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