11-16-2013, 02:56 AM,
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Gordon
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RE: Maximum allowed RPM
Hi Shantanu
What is the diameter of the part? RPM alone will not tell you the surface speed or the forces acting at the surface. I have sprayed parts with surface speeds up to 10 m/s using plasma and HVOF with no coating problems. The smaller the diameter the higher the RPM needed.
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11-16-2013, 05:04 PM,
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Gordon
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RE: Maximum allowed RPM
Hi Shantanu
I think I interpreted your question wrong. If this about forces acting on a coating during service, then my comment on the diameter being important stands. Also important will be the mass of the coating supported by the weakest point, usually the coating/substrate interface.
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11-18-2013, 09:54 AM,
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shantanu
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RE: Maximum allowed RPM
(11-16-2013, 05:04 PM)Gordon Wrote: Hi Shantanu
I think I interpreted your question wrong. If this about forces acting on a coating during service, then my comment on the diameter being important stands. Also important will be the mass of the coating supported by the weakest point, usually the coating/substrate interface.
Hi gordon,
Thanks for your replies...
Bearing seat diameter is 40 mm and length (width) is 30 mm. Part RPM is 12000.
My question is actually exactly what Djewell pointed out; how do we know when the centrifugal force of a rotating part (that is at what RPM) exceeds the bond strength of the coating / cohesive strength of the particles resulting in coating failure?
Regards
Shantanu
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11-19-2013, 12:00 PM,
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Gordon
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RE: Maximum allowed RPM
Hi Shantanu
For bearing seat diameter is 40 mm and length (width) 30 mm. Part RPM 12000, with a coating thickness of 1mm the stress generated at interface will be very roughly in this sort of order:
Tungsten carbide based coating: 0.5 MPa
Steel based coating: 0.25 MPa
So this should be well within working limits of most coatings.
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11-22-2013, 07:01 PM,
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shantanu
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RE: Maximum allowed RPM
(11-19-2013, 12:00 PM)Gordon Wrote: Hi Shantanu
For bearing seat diameter is 40 mm and length (width) 30 mm. Part RPM 12000, with a coating thickness of 1mm the stress generated at interface will be very roughly in this sort of order:
Tungsten carbide based coating: 0.5 MPa
Steel based coating: 0.25 MPa
So this should be well within working limits of most coatings.
Hi Gordon,
Numbers always help!
Thanks so much
Shantanu
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