Ceramic Shear Key

[adn1975]

I have an application that currently uses a brass shear key. It is functional, however I would like to use a material that has a high strength for start up rotational loading but under a high impact force will fail faster than the brass. Any material recomendations would be greatly appreciated.

(not sure if this is the right forum to discuss this, but everyone on here seems to have a virtual infinite plethora of resources)

 

[Heckler]

Why add the extra cost of using ceramics when a high strength alloy steel (8630) will do the job?

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right." -- George Best

 

[TheTick]

Are there stock ceramic keys available?

 

[adn1975]

I need something that breaks quickly, @~600lbs of force. i'm sure the yield on that alloy is more than that.......

 

[Heckler]

So you want something that will with stand the start up load but will fail if something happens to the pulley. Why would you want to have a safety mechanism like this....if it fails you will bugger up the shaft! Why not have some clutching mechanism that free wheels at the desired load + a margin?

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right." -- George Best

 

[adn1975]

shaft is a cheap component, compared to the 100k of damage because the shear key didn't shear quickly e-nuff. long term solution could be a clutch, but while this is out for remediation i'm searching for a key that will shear faster than the brass.

 

[Jumble]

Hi

How is your shear key arranged, Is it a beam or a conventional key (inside a hub)? I have done very well with cast iron beams tied in with a bronze friction clutch activated by disk springs compressed to a known height. Normal loads drive through the friction cluch, small overloads are taken by the Cast Iron beam larger loads shear the beam and slip the clutch. Unless the load is very smooth trying to take all the load through the key results in fatigue failures or you have to have a very large overload in order to break the key