very high speed spindles question.
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  1. #1
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    Default very high speed spindles question.

    Background:

    I've been asked for input on designing / retrofitting an very fancy thermal environmental test machine to handle much higher speeds for testing speed sensors.

    They currently have an air bearing spindle belt driven to 8k rpm. Imagine a VMC spindle but poking up into the bottom of an insulated box. They mount various tone rings to it and test new speed sensors. A computer can move a motor controlled slide carrying sensors to test them at different air gaps / spindle speeds /temperatures etc...

    They would LIKE a similar unit to go to 100k rpm, or at least 50k.... no clearly defined requirements yet.

    I said why not just put a high speed mini machine tool spindle inside the existing box and reuse all the other apparatus. Either Electric or air turbine, maybe even a planetary type spindle speeder except that the existing spindle interface is not "friendly" to that.

    I would have my targets, which are +/- 10mm diameter shafts with notches or flats balanced of course. they can have reduced 8mm shanks or whatever handy for the spindle collet interface.

    Now my question:
    Ballpark- what does a "high speed electric motor spindle" and drive cost? -from a major manufacturer like NSK.

    like these, or similar. http://www.nskamericacorp.com/Catalo...alog_2017/105/


    thanks

  2. #2
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    What's the duration of the test? How do you check balance of the system? And what's your budget?

    I can't provide costs, but if I were doing this I'd be looking at air spindles for short use, electric for long use (due to cost of compressed air), and if you're holding 10mm shanks I'd want that as my collet/holder method rather than a reduced shank. Mostly for safety, I've had small errors in balance turn into "dammits" when a smaller shank failed - it can happen in a flash.

    So back to that issue, balance - how will you monitor that? Past 20K it's a biggie unless you're dealing with dentist drill sized things.

  3. #3
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    I just spoke to their sales. Very nice people, easy to talk to. $5k for a 60k rpm E3000 series spindle with everything.

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    The NSK or Nakanishi spindles cost about 6000$ for the top end models.
    Add 1000$ or less for some collets and stuff.

    The small required driver system (in that price) includes the compressor.
    Less than 1 micron runout, guaranteed.

    It´s near silent.
    Amazingly good.

    NSK is i think 60-80k rpm, these days.
    I talked to one of their engineers at EMO, and played with one.
    They are supposed to last years, in industrial use.
    I have never ever seen them lambasted online.

    If I wanted a high speed spindle, Nakanishi/NSK is what I would buy.
    They are like near-perfection in mechanical engineering.

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    Quote Originally Posted by hanermo View Post
    The NSK or Nakanishi spindles cost about 6000$ for the top end models.
    Add 1000$ or less for some collets and stuff.

    The small required driver system (in that price) includes the compressor.
    Less than 1 micron runout, guaranteed.

    It´s near silent.
    Amazingly good.

    NSK is i think 60-80k rpm, these days.
    I talked to one of their engineers at EMO, and played with one.
    They are supposed to last years, in industrial use.
    I have never ever seen them lambasted online.

    If I wanted a high speed spindle, Nakanishi/NSK is what I would buy.
    They are like near-perfection in mechanical engineering.

    No experience with the large ones like the OP wants...

    But I can tell you the small ones (like the iSpeed3 systems) hold up VERY well to continuous use in an industrial setting. Well worth their price. And they make it not miserable to run things like .017"Ø endmills.

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    Years ago I worked on a similar product design involving ultra high speed centrifuges. A disk affixed to the bottom of a titanium rotor was used as a speed sensor. The problem was that the disk would shift on the axis due to precession. These rotors weighed upwards of ten pounds and were used at over 100k RPMs. The drive shaft was designed to flex and assume an S shape (because of precession)with very heavy rotors. If it didn't it would snap off and cause a very nasty crash. The fact that the target disk would be on a different axis depending on the speed made some interesting design challenges for the speed sensors. This is all to say that the drive motors and spindles are readily available on the ultra centrifuge market at surplus cost. As far as safety is concerned in a testing environment, just buy a surplus ultra and you get the very precise speed control , continuous duty , precision bearings and spindle and two inches of armor. Beckman and Sorval come to mind.

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    Quote Originally Posted by crossthread View Post
    As far as safety is concerned in a testing environment, just buy a surplus ultra and you get the very precise speed control , continuous duty , precision bearings and spindle and two inches of armor. Beckman and Sorval come to mind.
    With a side of unknown pathogens for good measure.

    I've seen vids of the aftermath of centrifuge crashes - it's not pretty. Scale it up to a commercial jet engine and there'd be nothing left of the airliner.

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    Pathogens would not be a problem. They are easily decontaminated with Sodium Hypochlorite. Losing a sample in an ultra is a major concern, not so much for the contamination issue but for an imbalance condition. Yes, a "rotor mishap" can be very exciting. There have been quite a few instances where a chemical reaction from the AL liner (which holds freon filled tubing) has caused a thermal explosion. As the rotor disintegrates it powders the AL liner which acts as the fuel. The steel barrier generally stops the rotor parts from coming through the sides but the top which is only about 3/4 inches thick is not designed to handle an explosion of this type. Rotor parts have been found in the lab above where the mishap occurred.


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