Hardening parts Cryo vs. Nitriding

[Guest]

I've heard several members speak of cryo treating parts and just arrived at the question of nitriding while in the process of planning an offset grind of my crankshaft. Nitriding is a tried and true process so why the cryo treatment of important parts in the drivetrain during a power increase as opposed to nitriding which documentation to its effectiveness is not hard to find, versus cryo treatment which has far more sooth saying than documentation to back up its claims.
Here is a detailed highly informative read on crankshaft design and hardening with an excellent graph of the benefits of stock vs. heat treating vs. heat treating plus nitriding hardness effects. If nitriding is effective on cast and hyper pistons, it might be a great option for strength enhancement before going to custom parts.

http://www.epi-eng.com/piston_engine_technology/crankshaft_design_issues.htm

I don't know much about the process but I'm sure someone here can offer some insight, such as the machinist on the forum.

[geoffinbc]

Well I know nitriding is only a surface hardening process which is desirable for bearing surfaces and wear surfaces like cam lobes and such. You do not want an ultra hard crank because there is bending that happens whether you like it on not and a hard material will just crack

I believe but am not 100% positive but cyro treatment hardens the material right through. Good for gears chains and pistons.

[robertisaar]

Well I know nitriding is only a surface hardening process which is desirable for bearing surfaces and wear surfaces like cam lobes and such. You do not want an ultra hard crank because there is bending that happens whether you like it on not and a hard material will just crack

I believe but am not 100% positive but cyro treatment hardens the material right through. Good for gears chains and pistons.

right, nitriding is surface only, i did it for a few hammer heads before, COMPLETETLY prevents it from mushrooming if done right, no matter how old it is or how much you use it...

i'm not sure where to stand on what process is a good idea or not for the crank, because, as stated, it will flex quite a bit. IIRC a top fuel crank rotates something like 15* instantaneously when they drop the hammer off the line. obviously we're not dealing with billet cranks in a 660, but the same concept applies.

i'd get answers from a major crank manufacturer(that DOESN'T have a conflict of interest) before attempting anything like this...

[60dgrzbelow0]

There is a third alternative as well... "Hard Chrome Plating". When done carefully...with proper preparation of the metal journals... this process can make a crankshaft virtually Bullet-Proof, short of anybody slamming a fifty ton hammer down on some V-6 pre-casts...and doing it right:

http://www.endyn.com/quality/bulletins/pdfs%5CTB%5C1020.pdf

[robertisaar]

^ not a bad idea...

the cylinder walls in one of my dad's snowmobiles is chrome plated, and even though it's sat largely uncovered with plugs out of it for at least 10 years, it still turns over easily.... i imagine since chrome usually has a nice smooth finish, it reduces friction from the bearings as well.

[60dgrzbelow0]

It is interesting in the way they accomplish this... The crankshaft is naturally "pedigreed" with all the preliminaries to get rid of the "Weaker Sister" and then encapsulated in a thick waxy substance...like Bee's Wax ...something inert to all the corrosive cleaning acids necessary to strip and prep just the journals. Then in an orderly step-by-step procedure...the journals are electroplated in steady doses until the surface is laid down with a thick enough coating that can withstand some additional machining and final polishing. When finished...you have a crankshaft that will remain true and very sturdy for the life of the engine...

[RedBird]

wow.... that hard chrome plating sounds like the thing to do for a lot of parts. crank journals, cylinder walls, lifter flats or rollers, maybe even cam lobes?