Re: [Emc-users] Lathe cutting forces

2015-09-17 Thread Ed 
On 09/17/2015 07:57 AM, andy pugh wrote:
> To size motors, screws, bearings etc for my CNC lathe conversion I
> have been trying to find cutting force data.
>
> http://www.ijera.com/papers/Vol4_issue4/Version%201/U044134144.pdf
>
> Seems to say that a feed force of 100N is about normal.
> This seems rather less than I would have guessed.
>
> Does anyone else have any feel for this. I have been designing around
> 2kN, and I know that many CNC lathes have multi-kW Z servos.
>
Many CNC lathes push large twist drills and spade drills through some 
tough material. How big do you plan?

Ed.


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Re: [Emc-users] Lathe cutting forces

2015-09-17 Thread Rick Lair 
I know that our big machines have 7.5 kw Z axis motors, and 3.5 kw X 
axis motors.


On 9/17/2015 8:57 AM, andy pugh wrote:
> To size motors, screws, bearings etc for my CNC lathe conversion I
> have been trying to find cutting force data.
>
> http://www.ijera.com/papers/Vol4_issue4/Version%201/U044134144.pdf
>
> Seems to say that a feed force of 100N is about normal.
> This seems rather less than I would have guessed.
>
> Does anyone else have any feel for this. I have been designing around
> 2kN, and I know that many CNC lathes have multi-kW Z servos.
>

-- 

Thanks


Rick Lair
Superior Roll & Turning LLC
399 East Center Street
Petersburg MI, 49270
PH: 734-279-1831
FAX: 734-279-1166
www.superiorroll.com


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[Emc-users] Lathe cutting forces

2015-09-17 Thread andy pugh 
To size motors, screws, bearings etc for my CNC lathe conversion I
have been trying to find cutting force data.

http://www.ijera.com/papers/Vol4_issue4/Version%201/U044134144.pdf

Seems to say that a feed force of 100N is about normal.
This seems rather less than I would have guessed.

Does anyone else have any feel for this. I have been designing around
2kN, and I know that many CNC lathes have multi-kW Z servos.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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Re: [Emc-users] Lathe cutting forces

2015-09-17 Thread Erik Christiansen 
On 17.09.15 08:36, Ed wrote:
> On 09/17/2015 07:57 AM, andy pugh wrote:
> > Seems to say that a feed force of 100N is about normal.
> > This seems rather less than I would have guessed.
> >
> > Does anyone else have any feel for this. I have been designing around
> > 2kN, and I know that many CNC lathes have multi-kW Z servos.
> >
> Many CNC lathes push large twist drills and spade drills through some 
> tough material. How big do you plan?

There's also a hefty carriage with a massive tool turret and motor to
accelerate at dollar-earning rates, plus bed friction to overcome, in
many cases. As well, the DOC and FPR in table 4 do not look much like
production roughing cuts with TC tooling and flood coolant.

The knurling gcode from earlier in the week would also require higher
feed force than the feed of 180 microns per rev in table 4, I figure.

Erik

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Re: [Emc-users] Lathe cutting forces

2015-09-17 Thread andy pugh 
On 17 September 2015 at 14:36, Ed  wrote:
> Many CNC lathes push large twist drills and spade drills through some
> tough material. How big do you plan?

My current lathe has stepper motors, and stalls if asked to push a big
drill, so in fact my 2kN number was derived from asking FS-Wizard what
the push force was an a 25mm drill.

However, when pushing a big drill I am not as concerned about Z axis
acurracy. I was looking for numbers to plug in to FEA calcs of my Z
bearing housing design.
This is an interesting puzzle, as there are advantages in keeping it
compact to keep the screw/nut as close to the work as possible.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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