Max Thermal Temperture for Bronze Alloy UNS C67300 1

[mfgenggear]

I need assistance, what the max temperature that the above Bronze alloy can be heated for shrink fit application.
that will not affect material properties.
tried to do a search, but found no linked data.

Please Advise
Thank You
Mfgenggear

 

[metengr]

ASM Handbook, Volume 4 has annealing temperature for C67400 which ranges from 800 deg F to 1100 deg F. I would use the 800 deg F limit for maximum exposure.

 

[mfgenggear]

Thank You metengr

 

[WKTaylor]

Strain-hardened bronzes will be affected by temperatures exceeding 300-F... most aerospace design guides won't permit heating in excess of 600F.

Also, any plating/coating on the part will dictate an upper-temperature limit of 250--500F... depending on the plating/coating.

Copper alloys and most coatings tolerate immersion in LN2. Any good reason 'shrink fitting' can't be accomplished using LN2 [~-220F?]... instead of high heat?

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[mfgenggear]

Hi Wil

Thanks for the reply, the bronze part is not coated or plated, and the part has an Internal diameter that is shrink fitted to a shaft.
the shaft is place in cold box to -90 deg. F , but that said it is assembled by our customer. and our customer is having issues. I needed the temp's
so that I could calculate the shrink fit verses the amount of press. I needed to suggest to them to use LN2 for the shaft and to heat the Bronze alloy
to a higher temp. to obtain the proper clearance. I had did an extensive search and could not find reliable data. it was not on the material data sheets.
but the information given in assistance is very valuable, and I appreciate it.
by the way the shaft is AISI 9310 with carburize surfaces prone to cracking if excessively pressed.

Best regards
Mfgenggear

 

[tbuelna]

One issue with press fitting parts that have any significant amount of interference is the galling/smearing that can occur at the leading edges of the contact interface at assembly. If your installation requires interference, thermal fitting the parts is a much better approach. However, the trick to thermal fitting parts successfully is making sure the parts are accurately aligned and quickly pushed together in one continuous motion. Once the mating surfaces come into contact there will be rapid heat transfer and quick seizure between the parts.

Heated/chilled metal parts, especially ones with small mass or thin sections, can cool down/heat up quite quickly while being handled. So minimizing the amount of time required to fixture and assemble the parts is important. It is best to use a dedicated fixture designed to make the thermal fit procedure quick, easy and consistent.

 

[mfgenggear]

Hi Terry

Yep I am aware of that, I don't believe our customer is. why I inquired about the question for the max temp.
I have being doing this for while. bronze alloy is not common for our type of product.

Best regards
Mfgenggear

 

[WKTaylor]

mfgenggear ... I find this spec useful...

SAE AIR809 Metal Dimensional Change with Temperature

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[mfgenggear]

Thanks Wil

 

[racookpe1978]

Brass is a soft alloy - and will get softer at even 600-800 deg F. Be careful about distortion of the heated part while heating, during the soak period, and while it cools. Be careful to get the entire part evenly heated: If a propeller or fan-type blade, for example, you'll find the shaft and hub to be many degrees cooler than the "too-hot" blade tips. SO, the blades may twist or bend as you wait for the hub to heat up.