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Shoot peening + cryo treating mini gears
https://www.ausmini.com/forums/viewtopic.php?f=2&t=65277		 Page 1 of 1
Author:  NG [ Thu Aug 26, 2010 7:47 pm ]
Post subject:  Shoot peening + cryo treating mini gears
anyone done this yet?

i am! i will let you know how it go's lol :lol:
Author:  graham in aus [ Fri Aug 27, 2010 6:18 pm ]
Post subject: 
Where NG?

Website? :?:
Author:  NG [ Fri Aug 27, 2010 6:42 pm ]
Post subject: 
well i got my cryo treatment done some where else.

kicking my self, could have had it done by this one guy.

my gears are on the way to him now.

he has done mini gears before, there is a bit of work in the masking up of the gears he also dresses them he told me and nothing gets damaged.

he quoted me $15 per gear to dress tape & shot peen.

http://members.ozemail.com.au/~mtce/peeninfo.htm

you should give him a call tell him nick sent you his way.

im keen to try this, if all the big v8 guys to it and F1 racing teams then why not do it to a mini gearbox.
Author:  graham in aus [ Sat Aug 28, 2010 11:28 am ]
Post subject: 
Thanks NG, that looks like a really useful contact, nice Jedi Single seater, drool....

http://members.ozemail.com.au/~mtce/jedi.htm

I hope to follow this up at some stage and get some parts treated!

Excellent! :P
Author:  mickmini [ Sun Aug 29, 2010 12:31 am ]
Post subject: 
I was just looking at his website last week :lol:
Author:  Convertible Mini [ Sun Aug 29, 2010 2:46 pm ]
Post subject:  Shot peening
What does this process really do to Metal ? I remember having some Con rods done years ago on a race engine but can's remember if anything benefited from it.
Author:  VulcanBB18 [ Sun Aug 29, 2010 3:05 pm ]
Post subject: 
Was asking myself the same question earlier today :

http://en.wikipedia.org/wiki/Shot_peen

Would seem to be quite a few benefits in the engine field based on that wikipedia article.

cheers

Jacob
Author:  simon k [ Sun Aug 29, 2010 4:30 pm ]
Post subject:  Re: Shot peening
Convertible Mini wrote:
What does this process really do to Metal ? I remember having some Con rods done years ago on a race engine but can's remember if anything benefited from it.


I guess ideally you'd never notice that it had been done - all the parts just live longer than they might have... or survive heavy stresses that might have broken a standard part
Author:  MG Rocket [ Sun Aug 29, 2010 7:38 pm ]
Post subject: 
Interesting quote from that web site. Could be of interest for builders of hot Minis
Quote:
Shot peening of the fillet radius areas of crankshaft journal increases the fatigue life dramatically, and in many cases, customers have deleted nitriding in favour of shot peening the fillets. Our experience with nitrided crankshafts that have not been manufactured from nitriding grade steel is that they are prone to brittle fracture when flexed inside the engine. Further, it has been observed that nitrided cranks that have suffered from oil starvation are more prone to journal overheating cracks. This is in contrast to the belief that these journals can be easily cleaned up after a bearing failure and put straight back into racing service! An added bonus of shot peening over nitriding is the absence of distortion or growth of the crankshaft.
Author:  drmini in aust [ Sun Aug 29, 2010 7:44 pm ]
Post subject: 
MG Rocket wrote:
Interesting quote from that web site. Could be of interest for builders of hot Minis
Quote:
Shot peening of the fillet radius areas of crankshaft journal increases the fatigue life dramatically, and in many cases, customers have deleted nitriding in favour of shot peening the fillets. Our experience with nitrided crankshafts that have not been manufactured from nitriding grade steel is that they are prone to brittle fracture when flexed inside the engine. Further, it has been observed that nitrided cranks that have suffered from oil starvation are more prone to journal overheating cracks. This is in contrast to the belief that these journals can be easily cleaned up after a bearing failure and put straight back into racing service! An added bonus of shot peening over nitriding is the absence of distortion or growth of the crankshaft.

Way back when (the 60s) shot peening of cranks was pretty common. I did the brand new 1098 crank that went into my 1220 motor.
It survived being revved often to 8500rpm for 20,000miles. When removed (due to a gouged bore) the crank had 8 short fillet cracks, 2 per big end. But despite the abuse, it hadn't broken.
So yeah IMO shot peening does help heaps.
Author:  NG [ Mon Aug 30, 2010 8:45 am ]
Post subject:  Re: Shot peening
Convertible Mini wrote:
What does this process really do to Metal ? I remember having some Con rods done years ago on a race engine but can's remember if anything benefited from it.


yes it works, very well, you can do cranks but you will to get them straightened after or checked.

F1 & them big v8 things are all cryo treated then shot peened.

shot peening works the surface metal and compacts the top layer giving a composite stress, so its alot harder & less prone to small cracks thats what leads to failure.

it's a 50% increase in strength with no adverse affects and no brittleness, it also creates better oil lubrication and cooler running of metals.

for example a high torque mini puts high stress on gears then cracks form and it rips the gears apart.

the spoke to alot of company's they all do the same thing.

wrx gears are now shot peened from factory as the older Gbox's were crap.

it's not alot of money either but you must cryo then shot peen and getting the gears dressed in that order.

ill let you know how i go as my car will be back together in about 2 weeks and hopefully the sc12 running in another 4 weeks.

i have now had Cryogenic treated


gears/baulk rings/syncro hubs
/pins/planet gears/output shafts
drop gears

next is to have the gears shot peened and dressed.

you can do it to anything even low powered mini's, it makes it last alot longer then normal, I believe in it & the proof is out there fingers crossed my Gbox lasts & lasts & lasts :D
Author:  mickmini [ Tue Aug 31, 2010 6:32 am ]
Post subject:  Re: Shot peening
NG wrote:

it's a 50% increase in strength with no adverse affects and no brittleness, it also creates better oil lubrication and cooler running of metals.


Now that is a snake oil salesman claim if I ever saw one.

Shot peening will not increase strength. It can only increase surface hardness, if done correctly. Increased surface hardness will decrease the likelyhood of a surface crack from propagating, hence increase fatigue life of a manufactured part, if done correctly.

As I understand, cryo treatment evens out the solid solution that is all alloys. For steel it allows the solute carbon to settle into the interstitial spaces in the iron lattice more evenly throughout the crystal. Generally deformation by the lattice warping, or atoms sliding past one another in the lattice becomes harder with morecarbon atoms in the interstitial spaces rather than along the lattice boundaries. This is what prevents the brittleness that you can get by simply increasing the amount of carbon or other alloying elements, if done correctly. Having the carbon in the lattice instead of at the boundaries of the crystals also increases fatigue life. A 50% increase in strength of a manufactured part might be possible if you had a poorly manufactured part in the first place, but done incorrectly it can also reduce the strength of a factory part by more than 50%.

The bit about better oil lubrication and cooler running seems like complete crap to me. Lubrication is all about pressures and film strengths, especially in shear. I fail to see how simply shot peening or cryo treating can affect either of these. If you set up the clearances of your plain shell bearings etc and use the right oil at the right pressure for the load applied then it will work. Neither process will change the heat conductivity of the metal as far as I can tell, and if you have your clearances for lubrication set up properly you will not generate too much friction, hence no heat problem.


Not saying that anything you have had done is not worth it NG, just don't like things to be made out to be a mythical cure all when they are specifically applied processes to acheive specific outcomes.

cheers
michael
Author:  NG [ Fri Sep 03, 2010 11:43 am ]
Post subject: 
yeh sorry.

my words are incorrect it can give you 50% to 400% more surface strength

i agree with what you say.

it's all about the cracks starting in the gears then bam all gone.

the cryo is meant to strengthen the gear it self through to the core and it does work.

it is no cure to blow a box with big torque, he did say you will get longer life & be able to put more torque safely through the gearbox then what factory is.

if driven nicely it will last long time.

only way to find out :D
Author:  drmini in aust [ Fri Sep 03, 2010 3:35 pm ]
Post subject: 
Shot peening puts the surface layers in compression.
Author:  norton [ Fri Sep 03, 2010 3:46 pm ]
Post subject: 
Which parts of the gears get shot peened ? I thought they were case hardened anyway.
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