Thread: Max spindle rpm for Hafco AL960B

Originally Posted by slhouetteV8

Bearing life is as you say done using a simple formula. Operating speed, operating temp, diameter, type of bearing and quality are used to gain the working hours of the bearing. There are also nomograms around for this as well, should be able to find one on the net somewhere.

I meant to ask about heat. Cutting with cermet produces a LOT of it (the more the better), and on long runs this inevitably ends up soaking into the headstock. It gets warm-hot to the touch after some hours, at which point i give it a rest.

At what (approximate) point does the temperature start to adversely affect bearing life? I would have a stab in the dark and say the MAX they would ever see is 60 or 70c. I assume they are meant to run in environments hotter than this?

Originally Posted by andrew_mx83

See, i wanted a spindle brake but my lathe doesnt have one. I had rough plans to fit a small disc and caliper, but a bit of work involved.
I wanted more speed, so the VFD seemed to kill 2 birds with 1 stone. I have since discovered the Chinese vfd doesnt actually have provision for a braking resistor, they just tell you it does. I was hoping the drive could be used to stop the machine like a brake, but i have to settle for a reduced spin-down time instead.

maybe a brake motor would work for you they are only on off type thing no more control than that.
5 5 KW Electric Motor With Brake in Illawarra, NSW | eBay

i don't think 70 deg would be an issue.

If you're up for a bit of reading and a little math#http://nachi-tool.jp/bearing/pdf/Tech.pdf

Originally Posted by andrew_mx83

Are you suggesting to add felt above these gears to hold/drip more oil onto them as Simon suggested? Oil pours out of this region already.

What does the EP additive to?

Yes I have felt in that reservoir to slow the release of oil, on mine it came with what looked like a piece of surgical gauze which was completely useless, the oil would drain in less than 5 minutes.

EP additive, Extreme Pressure, something like like molybond 2.5 is good, about $16 at Bolts and Industrial if you have one of those stores near you.

Garry

I had a bad run with motors and my lathe was offline for 2 weeks which killed me, i'm not rooting around changing it again lol. Plus i like that variable speed, and 5.5kw is a bit excessive, they come with 1.5 standard

slhouette thanks for the link, if i get a spare minute ill crunch some numbers but i would have to "decode" the gearbox first and work out all the various shaft speeds and bearing sizes etc.
I think the speeds and temps i am playing with are well within the envelope from the brief reading i've done of other bearing literature.

Garry, where do you get the felt from? I will sus out some EP additive next time i'm at the bearing shop. Any downsides from this stuff?


Thanks for the help lads.