why softer face is rotary

[santoshdada]

in a mechanical seal why a softer face is rotary

thx in advance

 

[bk19702]

The softer face is not always the rotating face, but is almost always the spring loaded face. The softer face being the sprung member allows it to 'wear into' a harder surface, i.e. the harder stationary or non spring loaded face. In the optimum tribological scenario, we want two dissimilar materials with differing finishes and hardnesses so we maximize lubricity and upper PV limit capability.

Soft is a relative term, as even with hard seal face pairings there will be a hardness difference between the two. The exception is when you run like hard face materials against on another, which is not a common practice due to the huge drop off in PV limit capability.

 

[sreid]

Mostly, the soft seal is replaceable and the hard shaft is not. It's kind of a "No-Brainer" choice.

 

[santoshdada]

Dear sreid
if replacement is concept behind this then softer face should be stationary as it is easy and economical to replace then spring loaded face
i am quite agree with bk19702

thx

 

[santoshdada]

Dear sreid
if replacement is concept behind this then softer face should be stationary or non spring as it is easy and economical to replace then spring loaded face
i am quite agree with bk19702

thx

 

[sreid]

I answered too fast once again and didn't read the post correctly. My "Vision" was a "rubber" shaft seal. The shaft is hard and rotating and the seal is stationary and easily replaced. It wears and the "Hardened" shaft does not.

So in the OP, what does "Mechanical Seal" mean exactly.

 

[bk19702]

Probabaly worth while to read and understand the post fully before responding. Mechanical seal as stated in the OP (at least how I comprehended it, anyway) should be referring to contacting end-face seals and any variation of them.