Time at max rpm?

[Hennessy]

I am wondering if any one knows how long you can run a 4020 spindle at max rpm (10,000 rpm) with out having it explode. I am currently drilling about 6,500 holes at 10,000 rpm with a run time of 1.5 hours. i am a little worried because i am getting heat build up. its not hot hot yet but i don't want to smoke the spindle. the chiller is broken so i know that's part of the problem... i just don't want to have some one say "well it says here ..." after i already smoked a spindle.

Thanks, Hennessy

[denmar]

why 10k rpm????

[Hennessy]

.039 carbide drill at 15 ipm .... parts are an emergency (i need 18 done by Monday) that's why i am working on a Saturday.

[encarlisle]

took about 7 hrs milling an intricate cavity at 10k but machine had quite a few hours on that spindle so you should be ok, get the chiller fixed.

[cadman]

From Fadals Maintenance Manual:

7.5K & 10K GREASE PACKED SPINDLES

"Spindles operating under 8,000 RPMs need no cool down period regardless of on time or load to the tool."

"Fadal recommends that Spindles operating at over 8,000 RPMs for extended periods of
time should be shut down for a period of at least 20 minutes after every 5 hours of
continuous operation. This will allow cooling of the races and re-lubrication of the
grease lubricated bearings. The actual load to the spindle is not a factor at higher
RPMs. The time period should be monitored as closely as possible to increase spindle
life."

If you have the air/oil spindle, I believe you can run those as long as you want at max rpm. I'd place a call to Fadal's service dept. to verify.

[little bubba]

Ran one job a few years ago, 18-20 hours a day for almost a month, about 85% was at 10k. That wasn't a problem and as far as I know that spindle is still in good shape, but.... it wasn't MY machine.

If the chiller isn't working, is the pump at least working? If the pump isn't working, I'd probably keep it under 8k, but that's just me, or only short bursts up to max RPM.

I remember reading somewhere that the 10k spindle is really an 8k spindle that CAN DO 10k.

[Delw]

with the chiller broken I wouldnt do it for very long.

to get by for the weekend go get a evap cooler pump or a pond pump get some 1/4 -3/8copper tubing.2 rolls if you have the cash, ( copper was expensive) connect the rolls of copper together and stick them in a cooler. dump ice over them
hook the pump up to the bucket thats holds the dow frost and the line from the the other end of the copper to the line to the spindle, make sure the return goes back to the buck of dow frost.

the cooler with the ice and copper will cool the dow frost, you can use dry ice also.

it wont melt fast but if your in a hot area drill a hole through the cooler so the cooler is sealed.
I used ice on mine for 3 days till I got the unit fixed, seems everything always breaks ona friday afternoon.
might sound redneck but it will work in a pinch and you can save your spindle and a pcs of mind.


Delw

[ThatguyDave]

Thanks cadman, I remember reading that and you saved me from having to dig through my stack of manuals to reiterate it.

I'm wondering though, what does the inside of a Fadal spindle look like? How many bearings are there? Where exactly is the coolant going? Does thru spindle coolant completely change the equation and allow full on running with no duty cycle requirements? If yes could a low or no pressure thru spindle coolant delivering little in the way of chip evacuation be successfull in cooling the inner bearing raced to facilitate running WFO indefinately?

Gotta get back to assembling my machine.

[cadman]

Originally Posted by ThatguyDave Thanks cadman, I remember reading that and you saved me from having to dig through my stack of manuals to reiterate it. I'm wondering though, what does the inside of a Fadal spindle look like? How many bearings are there? Where exactly is the coolant going? Does thru spindle coolant completely change the equation and allow full on running with no duty cycle requirements? If yes could a low or no pressure thru spindle coolant delivering little in the way of chip evacuation be successfull in cooling the inner bearing raced to facilitate running WFO indefinately? Gotta get back to assembling my machine.

I didn't have thru spindle coolant on my Fadals, so I couldn't give a definitive answer on any cooling effect it may have, but I don't see it making any difference at all as far as cooling the bearings. The coolant passage is through the drawbar, and the only contact the drawbar makes with the spindle is indirectly by way of the lube coated belleville springs, the drawbar retainer, and the toolholder. Any real world cooling of the bearings would most likely be close to zero as far as I could see.

[Hennessy]

Thanks guys for all the reply's ... i shut it down Saturday after about 5.5 hours that is definitely the limit on this machine. as for getting the chiller fixed i don't think it is going to happen unfortunately.... who ever had the machine before us ran strate water in the chiller instead of dow frost, all the lines are full of rust and the bearing blocks are ether plugged with it or rusted to the point they leek.. i don't like to say this but it has far to many problems to fix.

Originally Posted by little bubba Ran one job a few years ago, 18-20 hours a day for almost a month, about 85% was at 10k. That wasn't a problem and as far as I know that spindle is still in good shape, but.... it wasn't MY machine.

Just to clarify... i don't own it... i just try to treat all machines like i do.

the parts are coming out good tho so the boss is happy it is just going to take a little longer than we hoped to get them done.

thanks for all the help

Hennessy

[Neal]

Hennesey--
On a grease pack spindle, we recommend run at maximum RPM for no more than 5 hour. At that time there should be a 10 to 15 minute cool down period to allow the grease to flow back into the bearings.
This recommendation is stated in the Fadal Manuals.

Neal

[little bubba]

Originally Posted by Hennessy Thanks guys for all the reply's ... i shut it down Saturday after about 5.5 hours that is definitely the limit on this machine. as for getting the chiller fixed i don't think it is going to happen unfortunately.... who ever had the machine before us ran strate water in the chiller instead of dow frost, all the lines are full of rust and the bearing blocks are ether plugged with it or rusted to the point they leek.. i don't like to say this but it has far to many problems to fix.

I had one that had run straight water, it was mostly the pump that was clogged up and useless. As for the bearing blocks, for the liquid cooled ball screws, I've unplumbed them on 3 machines now. Honestly these are not rocket fast machines and they have some pretty good sized screws, and the second one of those seals leaks, you can kiss your thrust bearings good bye.

If you want to take 15 or 20 minutes and play with it, I would bypass all the bearing blocks, and then try blowing the lines out. The nasty rusty stuff, that turns into a nice solid clump seems to settle at the lowest point, in the pump.

For a new pump, they can get expensive, its just a soda fountain pump. McMaster Carr sells one, but the guts are different, uses a rubber impeller instead of the vein style of the original. I've picked up a spare on e-bay for about $60.

Just to clarify... i don't own it... i just try to treat all machines like i do.

You may feel that way, but when its your money maker that you paid hard cash for, it gets a little more TLC, and on the opposite end, you can make the risk/benefit decisions a lot easier and you may end up pushing it harder than you would push somebody else's machine.


As long as the boss is happy, weather it be you or somebody else.