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6061 T6 aluminum need to heat up

tait03

Plastic
Joined
Oct 5, 2017
Hi everyone,

Customer wants me to put a 9.75" 6061 T6 aluminum rotor onto a 1" shaft need to heat up the rotor to right around 350 f and that's where it begins to lose it's T6 temper does anyone know how long to put it in the oven to make sure I don't overheat it actually?
 
soo, what is the press? 350 is like 4 thou if I did my math right, any reason you cannot shrink the shaft also, dry ice ought to drop it a bit

would seem if you are threatening to heat it past its temper maybe the press is wrong............
 
I had a supplier tell me 15-20 minutes would not be a problem. We were silk screening tubes and that was all we needed to cure the paint. If memory serves going past 30 minutes would start to be a problem.
 
Gustafson
the press is close to .003 .0028 to be correct so that it is safe against torque as well.

And people say to key the rotor but have no previous experience keying it and were not sure if you can key and press fit something?


Larry
if i attach one to the rotor how will i be sure if the thermocouple will be reading the temperature of the rotor of the air in the oven surrounding the thermoucouple?
 
Hi everyone,

Customer wants me to put a 9.75" 6061 T6 aluminum rotor onto a 1" shaft need to heat up the rotor to right around 350 f and that's where it begins to lose it's T6 temper does anyone know how long to put it in the oven to make sure I don't overheat it actually?

If you need to heat it to 350F for the fit, you must keep it in the oven long enough to reach this temperature. This depends on the size of the part and on the oven. Any shorter times means it did not reach 350.
In order to prevent temper loss I would not go over 250. Cooling the shaft will help as you can cool down to -320F in liquid nitrogen. If there is a facility supplying LN in your area you can obtain a small quantity and keep in a thermos for a few hours. I have a glass vacuum flask, little over 0.5 gallon, and the LN keeps in it for most of the day when (lightly) closed with a Styrofoam lid.
 
If you need to heat it to 350F for the fit, you must keep it in the oven long enough to reach this temperature. This depends on the size of the part and on the oven. Any shorter times means it did not reach 350.
In order to prevent temper loss I would not go over 250. Cooling the shaft will help as you can cool down to -320F in liquid nitrogen. If there is a facility supplying LN in your area you can obtain a small quantity and keep in a thermos for a few hours. I have a glass vacuum flask, little over 0.5 gallon, and the LN keeps in it for most of the day when (lightly) closed with a Styrofoam lid.

Second best is dry ice and acetone or isopropyl alcohol - goes to only -108F, but you can buy acetone/alcohol at any hardware store and dry ice is easy to find. I can get dry ice at the local ice cream store in small quantities (1 lb for ~$1.50). My local ice supply also has it, but the min quantity is 5 lbs there.
 
I can get dry ice at the local ice cream store in small quantities (1 lb for ~$1.50). My local ice supply also has it, but the min quantity is 5 lbs there.

Smart and Final is also a pretty good source for dry ice, it's usually in a cold box near the checkout area, can't remember how expensive it is.
 
And people say to key the rotor but have no previous experience keying it and were not sure if you can key and press fit something?

we have used keys on heat/cooled press fit shaft assemblies. The key (1/4sq in our case) was attached to the shaft using a 4-40 shcs, and had a very generous lead on the end that met the pulley first. We made sure we had a good slip fit between the key and pulley before final fitting.
 
I would freeze the steel and heat the aluminum rather than over heat the aluminum.

Also remember to freeze whatever implements you are pushing the steel in with if it lacks mass.
 
Yup, the 350 degree heat is for a differential. At room temp of, say 73F, you will actually have a differential of only about 280F. If you can just get the shaft to 0F, you can get away with heating the rotor to 290F. Get it below 0F with any of the methods listed above and you'll get away with even less.
 
Its time at temp that matters with alu too in some ways more than actual temp, so either preheat the oven or just sticking some serious BTU's into the part fast with a gas torch is a far better idea. A large roofing - plumbing torch (i love my sievt torch which as of a couple of days ago even helped with the heat to fix the flying Scotsman steam train!) torch will bring a part like that to temp fast, equally being alu its easy to heat one side and measure temp on the other with a contact probe and not over shoot by much at all. You realy don't need any soak time with a alu part of thoes dimensions, once its hot its hot all the way through unlike steels or stainless! Speed is your friend on this one
 








 
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