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please, a limit for max rpm on BT50 ?

deadlykitten

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Aug 5, 2016
Hello all, we have here an mb66vb + bt 50 + max rpm = @12k

what do you think that should be the upper rpm limit that i should use on that mill ?

i am not asking about cases like this one : machining at @10k rpm with a small tool : in such a case is obvious that a smaller taper is better, or a spindle attachement :)

it is our only cnc mill, thus we dont have more such machines, so to consider one for roughing / bumping

what limitations would you consider, so to have the cnc in good shape ?

... and is there a G50 for mill ? kindly !
 
That's really dependent on the condition of the spindle and balance of the tooling, not to mention stress at larger radius (in other words, don't run a 12"/300mm OD facemill at 12K RPM).

If your spindle is in good repair and you're using balanced tooling of reasonable size, then when working in softer materials I'd expect a 1"/25mm cutter to be safe at maximum speed (feed dependent of course). I don't think I'd go over a 4"/100mm facemill at that speed, and I'd confirm with the manufacturer that the tool is safe at that limit. And again, balance is critical.

Can you give us actual examples of what you'd like to run? And have you checked the condition of the pull studs and drawbar clamping load? Everything matters when you push the envelope.
 
Can you give us actual examples of what you'd like to run? And have you checked the condition of the pull studs and drawbar clamping load? Everything matters when you push the envelope

hy Milland :) it was a general question : for example someguys say that they wont go over x% spindle load ... and is one thing to dont go over x% at 6k rpm, and another at 10k rpm

machine is prety new + in good condition :) i am thinking to buy a drawbar_clamping_load after i saw recently a reply from that guy from MaryTool

i can not give you certain examples : i had a case where i needed to cut in aluminium, and i used a o50 face mill at 8000 rpm ... even if cycle time was ok and vibrations were normal, so we could get a normal machining price, i stopped because i thought that it was too much for the cnc : a bt50 is not built for high rpm, but to handle better big radial forces, that dont occur at 10k rpm

... onestly, i was thinking about 6000-8000 rpm, but i would realy need&apreciate any advice; kindly !
 
If Okuma mounted a 12K BT-50 spindle into the machine, I'm pretty comfortable that it can use the entire spindle speed range, when tooled appropriately. I wouldn't go crazy, but if you're not getting excessive vibration or noise from the machine then keep at it.

In general you will see faster wearing out of the spindle bearings when run at maximum, but they'll wear at 5K too. If you get enough profit from running more jobs through the machine to make up for the quicker need for a rebuild then you should do so.

In your case, as it's a one machine shop, it probably makes sense to program for longer life, as having the machine down would be a pain.
 
If you get enough profit from running more jobs through the machine to make up for the quicker need for a rebuild then you should do so

you dont know how much i pray that someone with 2 gold bars/ingots will enter here, and i will machine them without worries at full speed :)

until than, i keep it low :)

... also, each setup i program not to be faster, but stable, so to keep tolerances and reduce the frequency of corections, etc
 
Spindle limits are more spindle bearing design and balance of the assembled tool than taper.
Seen 50 tapers on mag bearings run over 80,000 with no problems.
Of course cutter bodies have to balanced mounted in the adapter at these kind of speeds.
Not sure I understand the question.
Bob
 
Seen 50 tapers on mag bearings run over 80,000 with no problems.
Bob

You, sir, have boggled my mind. I'm trying to think of how the stiffness of a magnetic spindle capable of doing real work at that speed is maintained, and I think it involves lots of electricity and water cooling. Any chance of information (or video!) links to the beast?
 
You, sir, have boggled my mind. I'm trying to think of how the stiffness of a magnetic spindle capable of doing real work at that speed is maintained, and I think it involves lots of electricity and water cooling. Any chance of information (or video!) links to the beast?

this is why elite_mechanics_guys obey to novice_electronic/mechatronic_guys :)
 
my dmu has a table, on side of machine and in manual, which lists max speeds, requires balance, etc for various length and diameter tools. and indeed it contradicts spinning an 8" facemill at 12000 rpm.
do you have such a doc for your machine
 
my dmu has a table, on side of machine and in manual, which lists max speeds, requires balance, etc for various length and diameter tools. and indeed it contradicts spinning an 8" facemill at 12000 rpm.
do you have such a doc for your machine

hy bryan :) i did not dig the manuals, but i can tell that there is no such thing on the cnc

please, may i ask for a copy ? kindly !
 
Max rpm I would run on you 12k machine would be 12k.
I run 15k on my 15k max rpm machines all the time.
 
deadlykitten - it's specific to my machine - it would be similar for your machine, but not the same....

hy / yup, i suppose so ; please, will you share an image ?

bearing id on my mill is 90

i think i should check the motor diagram, and try to figure it out from there ... i know i have it, but i never understood it
 
Hello all, we have here an mb66vb + bt 50 + max rpm = @12k

what do you think that should be the upper rpm limit that i should use on that mill ?

i am not asking about cases like this one : machining at @10k rpm with a small tool : in such a case is obvious that a smaller taper is better, or a spindle attachement :)

it is our only cnc mill, thus we dont have more such machines, so to consider one for roughing / bumping

what limitations would you consider, so to have the cnc in good shape ?

... and is there a G50 for mill ? kindly !

No CSS on mills, so no need for a G50 type function. RPM=RPM.
I got a CAT50 mill a little while ago with 15,000 rpm. Never personally run over 5k with this size holders. It's going to be interesting.:dunce:
 
No CSS on mills, so no need for a G50

hy mkd :) nice one, it makes sense ... i was asking so to protect the cnc from random guys that try to run random programs

maybe there is a posibility from parameters ?
It's going to be interesting.:dunce:

:) do you have a plan ?

I'd keep it below 15k...

hy Wille :) you are a sharp guy, and my mill has max 12k rpm, so i guess that it will always be less 15k ... so you are always true :)

please, did you mean something else ? kindly !
 
You, sir, have boggled my mind. I'm trying to think of how the stiffness of a magnetic spindle capable of doing real work at that speed is maintained, and I think it involves lots of electricity and water cooling. Any chance of information (or video!) links to the beast?

At one time supersonic machining was all the rage. Yes surface footage in a range no sane person would try.
It turns out the rules get turned upside down once you pass a certain point, cutting forces do a way downhill slide.
Problem turned out to be you could mill a part so fast that there was no way the rest of the line could handle it's output so no way to cost justify the machine.
Your high buck mag spindle ultra fast machine would sit and wait for a new part. Standard cnc controls could not handle the speeds the tool was moving at outside of simple face milling.
At these crazy speeds inserts would not stay in their cutter bodies from centripetal force so more added cost.
At this point in walked in Toyota, takt times and such and these programs got shelved.
Before the net became popular so I can't find a video. :bawling: I can not even find a decent deal on Turchan's stuff and they did incredible things.

No pictures, no proof, it did not happen. I understand that.
Maybe a deal for our great-grandchildren to work with once e and m time constants on a machine tool get smaller in our digital and analog world as we gain ground on both every year.
Bob
 








 
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