electricpete
Electrical
- May 4, 2001
- 16,774
We have an electric motor application for 2-pole motor with 6316 greased bearings.
D (bore in mm) is 80mm
N is 3600rpm
D*N = 288,000
Bearing housing typically runs 150F - 180F.
We use Mobilith SHC100 for all our motor applications. Very few problems, except in this application we seem to have poor bearing life and examination upon removal of bearings shows signs of overheating (grease darkens, some varnish deposited on bearing surfaces).
I am looking for ways to solve this problem.
I don't believe there is any abnormal loading on the bearing and I believe our fill practices are good (pack bearing full and cavity 1/2 full.
Mobil tells us this grease is limited to approx 250,000 D*N.
I read in the Machinery Tribology handbook that grease lubrication becomes challenging in the range 200,000 - 300,000, and generally not practical above 300,000.
Does anyone have recommendations for a good grease to use in high D*N number applications such as this?
Also I the handbook mentioned that much higher D*N numbers 400,000-600,000 were achievable in greased bearings if precision bearings (better ABEC tolerance?) were used with machined (vs fabricated steel) cages. Any thoughts or experience on this?
=====================================
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D (bore in mm) is 80mm
N is 3600rpm
D*N = 288,000
Bearing housing typically runs 150F - 180F.
We use Mobilith SHC100 for all our motor applications. Very few problems, except in this application we seem to have poor bearing life and examination upon removal of bearings shows signs of overheating (grease darkens, some varnish deposited on bearing surfaces).
I am looking for ways to solve this problem.
I don't believe there is any abnormal loading on the bearing and I believe our fill practices are good (pack bearing full and cavity 1/2 full.
Mobil tells us this grease is limited to approx 250,000 D*N.
I read in the Machinery Tribology handbook that grease lubrication becomes challenging in the range 200,000 - 300,000, and generally not practical above 300,000.
Does anyone have recommendations for a good grease to use in high D*N number applications such as this?
Also I the handbook mentioned that much higher D*N numbers 400,000-600,000 were achievable in greased bearings if precision bearings (better ABEC tolerance?) were used with machined (vs fabricated steel) cages. Any thoughts or experience on this?
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
