Newbie- Spindle Life time question

[PHiRe]

Hi,

I operate a Eumach DM2000 3 axis milling machine for a engineering firm in the UK, we have had the machine for 3-4 years now and in that time we have had 3 spindle bearing rebuilds and I was wondering if this is normal? Any ideas on life expectancies of spindles in hours of usage. It does get rather well used and on various different materials including, Billet and cast aluminium, Birch Ply wood, Steel and Expanded polystyrene.

Thanks
Jim

[laka]

We have three mills, one 15,000 RPM, one 12,000 RPM, and one 8,000 RPM. They are all over 5 years old. They all have original spindles and sound and perform like the day we got them. I'm sure they'll go for another 5 unless someone crashes them.

[PHiRe]

wow, this one is only a 8k RPM spindle that never runs its max in all programs we max it at 7k and this has never been crashed either (well not by me anyway and i use the machine the most).

I don't get it must just be quite low quality bearings may be, the first one the spindle locked solid after 11 months as the hydrolic cylinder that opens the tool holding Collet came loose and welded its self to the top of the spindle. Then when it came back from its rebuild it had weak low quality bearings and lasted 3 months. This time i left it running on a 5 hour sequence (on birch plywood) last night then came in this morning to it sitting with spindle servo error, half way through

[laka]

If you're cutting wood, and your bearings are dying then I'd say you definitely have some poor quality bearing.

Have you investigated any lubrication or maintenance problems that may be leading to bearing failure?

[PHiRe]

all lube seems fine all monitoring systems measuring right levels and oil to the right grade and maintenance done by myself except when we get the company who installed the machine in annually to service it (which was done approximately 4 weeks ago )

Come to think of it we have had one problem with the lubrication a couple of weeks ago the machine stopped because the lube temperature crept above 40 deg C and the machine cut out. Now i make sure the lubrication coolant radiator is clean and free of dust at the end of every shift

[Triv]

Wood particles can infiltrate -unsealed- bearings, absorb the grease and swell up.

With the grease removed, the wood heats up and carbonizes... becoming abrasive.

It may need a positive charge of .3-1 bar of FILTERED air.

[PHiRe]

hey Triv,

Thanks For that, the bearings are supposed to be in a sealed unit but i would imagine that tiny particles of wood dust can penetrate it. Sounds very plausible to me.

Cheers
Jim