Cryogenics in rc

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02-08-2010, 07:28 AM

R/C_Stunna

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Cryogenics in rc

first before you think I'm talking about freezing dead body's read this ignore this ^^^^ i have no idea how to get rid of it and its to late to try

<o></o>

Cryogenics is the study of how materials react at very low temperatures - usually bellow -180 C. This figure was chosen as a dividing line since the boiling points of 'permanent gases' such as helium, hydrogen, neon, nitrogen and oxygen, are all below -180 C, while the boiling points of the Freon refrigerants are above -180 C.<o></o>

The History of Cryogenic Stress Relief<o></o>

One of the most important breakthroughs in the field of cryogenics occurred in 1945, when scientists discovered that materials frozen to very low temperatures showed more resistance to long term wear. This discovery lead to the founding of the CryoTech company, who specialized in cryogenic processing by Ed Bush, in 1966.<o></o>

Cryogenic Processing and Stress Relief<o></o>

Cryogenic stress relief is very effective in relieving stress from parts before, during, and after machining. This stress relief process is very thorough, assuming that the warm up process is very slow and deliberate. If you rush the process, you end up re-introducing residual stress back in to the parts.<o></o>

Metal parts, castings, forging, plastica, and composite materials all respond well to cryogenic processing. It is a non-destructive process, which does not affect the carbon content of steel, and leaves any surfaces clean and free of oxides. Unlike heat stress relief, there is no discoloration. The process essentially deadens the stress in welded or machined components, and can make a big difference to the durability of parts requiring intricate machine processing.<o></o>

Aluminum can benefit from cryogenic stress relief, as can non-ferrous metals. They become stronger and tougher as a result of the densification of their molecular structure, making them as close to stress-dead as possible.<o></o>

Changes in Molecular Structure<o></o>

One of the main practical questions is what can be done to relieve the stresses before machining? Advances in cryogenics have revealed that when parts are treated to temperatures of around -300 F, at a controlled time / temperature cycle, all internal stresses are revealed. This is because of the alignment of the molecular structure that was distorted during the process. When parts that have been through cryogenic stress relief are machined, there will be no distortion on the machined surface. If there is any distortion, it will be due to improper machining, or dull tools.<o></o>

Cryogenics is still a relatively new science, and it is one that has a bright and promising future.

i got this article from ezinearticles.com/ i felt that this article is a good explanation but if you don't want to take the time to read it
here is the short and sweet
if you cool a metal in a controlled environment (down to around -300ºF) when you warm it up its better by what was explained to me it will handle heat better, and be more durable and the process very gentle.<o></o>

well my dad knows allot of people that do quite interesting and cool things and we were having a super bowl party so some of them were there and we got to talking and one of them has a business that does cryogenics for metal he told me what it does and i told him about my rc cars and i got to thinking there are sooooo many applications for this first talking just metals.(i will get to my favorite applications later)

Bearing casings and the balls would handle heat better and would have less wear so need to be replaced less often. the metals would be stronger and more durable so any aluminum part you can think of would just be better. i know this is the electric forum but i do some nitro as well and doing a engine block and piston would probably be good. now there is proof that this works because about half of the nascar sprint cup cars have some cryogenic parts like the engine block, pistons, drive train, and anything that moves or needs to be strong. i don't know how this would affect a small engine but im assuming that it would not do anything but good.

now for my favorite part. electronics and electric motors

As for electronics what was explained to me by my dads friend is that if you use this on a microprocessor (im not clear on this but maybe you guys can help does an esc have a microprocessor in it i think some do some don't if im wrong correct me) or any processor it helps with heat control. Im not 100% clear on all the details for the electronics but i know he said it would help on a microprocessor.

next we have the motors this part is interesting this guy has done electric motors before i don't know about brushed motors because we didn't talk about them but what i was interested in is brushless motors
here is what i know
what you would do is the windings not the magnets
you can expect a 20% increase in rpms
better heat control ( he explained this funny but what i think he meant is that it can handle more heat so it will be just as hot but it can handle the heat better so it can get hotter without damage)
and more durability

so here is my question to you guys i need a motor that can be disassembled so that i have the windings separate than the magnets, be able to run at high RPMs like 11.1v + a 20% increase in RPMs
i want my rustler to go about 60mph on road but have enough torque to run off-road i wll also need an esc that will run it. suggestions are greatly appreciated.

here is a little calculation say the motor has a rating of 5700kv and you put an 3s lipo on it (5700 x 11.1) you have 63,270 RPMs now a 20% increase makes it (5700 x 11.1 x .2 = 12,654) + 63,270) so you have 75,294 RPMs that's pretty fast but i used the nominal voltage do i need to use the peak voltage of the pack? here it is at peak voltage (5700 x 12.6) is 71,820 RPMs now a 20% increase makes it
(5700 x 12.6 x .2 = 14,364) + 71,820 makes it 86,184 RPMs and that is wicked fast i don't know the RPM limits on a standard brushless motor but i have seen on YouTube (i know great factual resource...lol)
a castle creations 7700kv motor on 3s this means more calculations (7700 x 11.1) is 85,470 RPMs now at peak voltage that's (7700 x 12.6) is 97,020 RPMs that cant be good right? if this doesn't make sense tell me i don't have a great handle on all this yet but i can always learn and advice is greatly appreciated.

alright back to the actual cryogenics

here is the best part its cheap i don't know how much my dads friend will charge me but i found some prices online on different small businesses web sites so I'm assuming
10-20$ per motor
5$ per 4oz of metal
i don't know if the prices would be different for a circuit board or what but that's what i know

i started at midnight and its currently 6:30 am ish and I'm out of dr pepper (wow i drank a whole 2 liter)
if this makes any sense at all I'll be happy i would love to see this go somewhere in rc I think it has great potential
if anyone has done this or knows anything about it let me know how it worked

and for all you who read my whole post/rant/whatever you want to call it
thank you

here is a little excel doc for finding the % of battery left on your pack i found it earlier and maybe it has nothing to do with this but i found it interesting
www.rcgroups.com/forums/showatt.php

</meta></meta></meta></meta>

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02-08-2010, 07:52 AM

Shabbernigdo

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RE: Cryogenics in rc

i dont think the gains net the extra production cost to do this for main stream rc companys. After market producers for car parts have been using cryogenicly treated parts for quite a while but they usualy come with a substancial cost as well.

As the tec becomes easier to come by it will continue to get cheaper.

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02-08-2010, 10:30 AM

Brainanator

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RE: Cryogenics in rc

the max recommended RPM's for the new castle motors are 100k RPMs, at least that's what it says on my 4600Kv.

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02-08-2010, 05:28 PM

R/C_Stunna

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RE: Cryogenics in rc

well i called castle and talked to someone he was able to answer my questions
first the new motors have an rpm limit of 100,000 RPMs
second you can open the new motors and get the magnets out and all the bearings but one in the back so my problem is that you cant cryo a full bearing because of the seal its either plastic or Teflon and cryo is now good for those things
my problem is he said you cant take the windings out of the case to get to the bearing, because of the way they are wound it wound work any more
which is a problem because i need that last bearing out if anyone knows about the new motors and there assembly i would love to hear about it.
thanks

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02-08-2010, 05:52 PM

Brainanator

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RE: Cryogenics in rc

I've taken my castle motor apart, and it's what he said...
front endbell is easy to get out, magnetic rotor comes out easily enough (lots of pulling)
but you aren't going to be able to get that last bearing out without....something crazy, it's back there good, and there are what appears to be epoxies and stuff holding the windings in.

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02-08-2010, 06:11 PM

Access

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RE: Cryogenics in rc

Quote:

ORIGINAL: Shabbernigdo
i dont think the gains net the extra production cost to do this for main stream rc companys. After market producers for car parts have been using cryogenicly treated parts for quite a while but they usualy come with a substancial cost as well.

As the tec becomes easier to come by it will continue to get cheaper.

The high-end racers and even many club racers are typically willing to pay top dollar for something that will give them a purported or perceived advantage over other racers, even a minor one. So you never know.

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02-08-2010, 06:56 PM

Lilredmachine

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RE: Cryogenics in rc

The problem with higher rpms in brushless motors isn't limited to just heat. Holding the thing together when it's rotating at that speed is the main aim. That Castles motors now come with a 100,000 rpm guarantee is incredible.

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02-08-2010, 07:26 PM

HandyRacing

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RE: Cryogenics in rc

I think this would make more practical sense:

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

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02-08-2010, 08:32 PM

Access

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RE: Cryogenics in rc

Quote:

ORIGINAL: HandyRacing
I think this would make more practical sense:

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

In practice that's a near-worthless thing when it comes to RC. We don't need to cool beyond ambient temperatures. If you need to keep something cool, you just put a heatsink on it and increase the airflow. Irl those things tend to be very inefficient so you end up generating a lot more heat than you move. You end up having to dissipate far more heat due to this inefficiency. The only time I could think of using a device is if you wanted to supercool your motor before a race or something like that. Irl they are only used when you need some kind of solid state cooling (no moving parts) that can bring temperatures below ambient and don't really care about efficiency or space.

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02-08-2010, 08:36 PM

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RE: Cryogenics in rc

Quote:

ORIGINAL: Access

Quote:

True but there not a majority of the RCpopulation. A lot if not most RC companys target the general rc population for there products although they have been introducing more nich type productsIEthe crawlers.

Now i could see some of the after market companys offering these type of parts as extras or upgrades or even the stock producers making these parts as upgrade parts to be bought seperate.

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02-08-2010, 08:55 PM

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R/C_Stunna

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RE: Cryogenics in rc

i dont quite see how a Thermoelectric effect gets me what im looking for
from what i understand a Thermoelectric effect is about making more voltage but i have a battery for that
maybe im completely off

what i am looking at doing is basically tempering the motor i dont know how it works on a electric motor but he has done it i could call him and ask for an explanation of what it actuly does to the motor (besides more heat control and around a 20% increase in total rpms)

but im not looking to keep the motor cooled constantly just one time in the cryo chamber then its good

also i still need a brushless motor that can handle the rpms (11.1v + 20% more rpms)
and i need to be able to separate the windings from the bearings and magnets to put the windings in the cryo chamber
thanks

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02-08-2010, 10:25 PM

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RE: Cryogenics in rc

My college metallurgy teacher told us about a friend of his who had his disposable razor cryo treated. He used it for years.

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02-09-2010, 01:23 AM

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FairTax4me

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RE: Cryogenics in rc

Quote:

(besides more heat control and around a 20% increase in total rpms)

It seem to me like there's a problem with this theory of increased RPMs as a byproduct of cyro treating. All electric motors create back EMF. The speed of the motor is dependent on load vs voltage. As the speed increases, so does the back EMF. At some point the back EMF becomes equal to the voltage powering the motor, and at that point the motor is not physically able to turn any faster (assuming the motor is unloaded). Drag from the bearings can make a small difference here, (unless they're shot) but the only way to increase motor speed dramatically (20%) is to increase voltage, or decrease the back EMF. Decreasing back EMF is done basically through changing the magnetic field of the motor, either by changing the windings or the strength of the magnet on the rotor. Weaken the magnet, back EMF goes down. Unloaded speed may go up due to this change, but loaded speed and torque will go down.
I don't see where cryo treating a motor can change the makeup of the windings enough to alter their magnetic field in such a way to make the back EMF of the motor go down, (resulting in the increase in loaded motor speed) and yet retain the same torque and power that it had before.

I may be way off base here. I'm no expert, bu I think I have a fair enough understanding of how electric motors work. I just don't see such a large gain in performance being reached by simply freezing a motor.

edit: The VXL3500 motor can be completely disassembled in the manner that you are asking.
http://www3.towerhobbies.com/cgi-bin...?&I=LXSGV5&P=7
I would be interested to know what your findings are if you do attempt this. Though I really don't think there will be much, if any, change.

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02-09-2010, 05:23 AM

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Lilredmachine

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RE: Cryogenics in rc

I'm guessing the theory is that the motor will become more efficient through increased heat handling ability, a drop in back EMF through less resistant windings. Whether it has any effect in the real world at this scale remains to be seen.

If you are actually going to do this, I suggest you use a motor with a kevlar or similar wrapped rotor to handle high RPMs. Unbonded rotors can shatter at the rpms you are talking of.

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02-09-2010, 10:54 AM

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RE: Cryogenics in rc

Actually as motor designs have become better (stronger rotors, better coils / cores, etc.) the back-EMF has increased. But in the end this has led to more power and speed, not less, b'cos of gearing and everything else. I remember when ROAR started to permit sintered rotors, novak, LRP, etc. went from bonded to sintered with the advisory you might need to increase your gearing a tooth or two b'cos the motors KV will drop a bit with the new rotors.

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02-09-2010, 12:15 PM

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R/C_Stunna

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RE: Cryogenics in rc

i dont quite know why it happens (i will call the guy that does the cryo today) but he says he has done it to lager scale brushless motors and has seen a 20% increase in rpms consistently

i am planing on doing this as soon ans i have a motor to do it with

i belive the vxl has a 50,000 rpm limit i need faster
thanks

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02-09-2010, 09:40 PM

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FairTax4me

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RE: Cryogenics in rc

Quote:

Absolutely. Stronger magnetism will lead to a higher back EMF, horsepower will increase because of the stronger magnetic field of the motor, but overall unloaded motor speed is decreasing.
I can certainly understand an increase in motor power due to lower resistance, its the RPM deal that's not making sense, and 20% still seems a bit on the high side.
This is one of those things that seems like it shouldn't work, but quite often people who doubt technological progress are proven wrong. People laughed at Edison until he proved to the world that electric light was possible. It's now considered almost "third world" to not have electric lighting.