What's new
What's new

Lathe running too fast with G96?

Cuda

Hot Rolled
Joined
May 21, 2005
Location
Alabama
I noticed today our Daewoo Puma 400 with Fanuc 21Ti control was running way too fast on large dia. parts, I was turning some 18.5" dia. wear rings made from super duplex and was wanting to turn 125 surface feet per min. that should be about 26 RPM, however the machine was running 50 RPM at 18.5 Dia. with a G96 S125 speed command??? The funny thing is if you manually move the tool down in X after starting the program the speed would remain at 50 RPM until the tool reached about 10" then the chuck would start increasing speed and at that point it would have the correct RPM for the dia. it was at. The only way I could make the parts was to use a G97 code to force 26 RPM. I think it may be a parameter issue?
 
How coincidental ! Last days i was running big SS parts on a puma 700 and i had the exact same problem.
Only i didnt notice the 50 rpm right away, and kept changing surface speed in the program, untill i saw it.
Took me a few extra inserts tho.
I just manually do override the rpm to a lower % right now, but if anyone knows of a parameter setting i would be glad to hear aswell.

What kind of puma 400 do you run, a LMA LMB or LMC?

You manually moved the tool to 10", that was the diameter where your SFM was 125, from there it catches up.
I noticed the same when facing the parts.
 
That is probably the minimum spindle speed allowed by the MTB, and it is almost certainly set in a parameter. Unfortunately, going lower under load may cause overheating of the motor.
 
What kind of puma 400 do you run, a LMA LMB or LMC?
It's a 400 LC with 21" chuck and 12 station turret, and I don't just run it, I also do the set up and programs.

Can you post the beginning of your program, especially where you tell it how fast to turn?
Do you have a gear range, like M41, M42, etc.?
Heinz.
www.doccnc.com
The machine has Low range M41 and High range M43
Program sample would look something like this...
N0001 G50 S300
(ROUGH O.D. WNMG432)
M41
G99
G0T0101
G54
G96 S125 M3
G0X18.5 Z.04 M8
G1Z-2.8 F.012
X18.55
G0 Z.04
X20 Z12. M9
T0100
M1
 
The program looks fine, I see nothing that should mess up your speed.
There is a guy at Daewoo, his name is Kaspar, I am sure he can help you.
Why don't you give him a call.
I just made a 40" part on a different machine, but the same control for a shop in Detroit and we had no problem.
The only thing different in the program was no G0 with the tool call, so it was T0101 by itself.
I have no clue if that has anything to do with it, but you might try it.
Do you know what the minimum RPM for your machine is?
The best of luck: Heinz.
www.doccnc.com
 
N0001 G50 S300
(ROUGH O.D. WNMG432)
M41
G99
G0T0101
G54
G96 S125 M3
G0X18.5 Z.04 M8
G1Z-2.8 F.012
X18.55
G0 Z.04
X20 Z12. M9
T0100
M1


This is the way I program this sequence:

T0101
M41
G97 M3 S25
G0 X18.5 Z.04 M8
G50 S300
G96 S125
WORK
G97 (sometimes I add S value here)
M9
T0100
G0 Z.04
X20 Z12.
M1
 
That is probably the minimum spindle speed allowed by the MTB, and it is almost certainly set in a parameter. Unfortunately, going lower under load may cause overheating of the motor.
My boss is going to HIGHLY upset if that's the case, he bought that machine to do heavy big work and that sometimes requires less than 50 RPM on big dia., I've been running it a lot on these big rings at 26 RPM @ .150/.200 depth of cut and .01 to .012 feed with only 20 to 30% spindle load showing and not a sign of bogging. I would think if 50 RPM was the min. it would not run any slower under any condition, we have a Mori Seiki SL25 and it won't run less than 35 RPM even if you tell it to run G97 S10
 
It's a 400 LC with 21" chuck and 12 station turret, and I don't just run it, I also do the set up and programs.


The machine has Low range M41 and High range M43
Program sample would look something like this...
N0001 G50 S300
(ROUGH O.D. WNMG432)
M41
G99
G0T0101
G54
G96 S125 M3
G0X18.5 Z.04 M8
G1Z-2.8 F.012
X18.55
G0 Z.04
X20 Z12. M9
T0100
M1

Sorry if i offended you by asking what machine your run, i do mean by running a machine programming, setup, making your own fixtures, fix your own problems, knowing how to align your turret, aligning the headstock and tailstock, fix the sheets when needed, replace bearings of the steady rest if available, align steady rest, keep coolant healty, change own filtermist, make programs while it runs, help other collegues with programming issues, make macros, program C-axis if available, setting up a toolsystem from the ground, knowing the inserts for turning milling and boring tools on the different materials, being able to make a big shaft fully automatic from a rough blank without any program interruption, shifting, placing steadyrest in the program, aswell as the tailstock, ect...

Oh wait i think i lost track, yes only running a machine like in pushing the green button is different.

I do like this

O0001(drawing number+customer)
G50 S300
G54
N1G00X...Z..G40G99
T0100(ROUGH O.D. WNMG432)
M41
G96 S125 M3
G00X18.5 Z.04T0101 M8
G01Z-2.8 F.012
G01X18.55
G00 Z.04
G00X.. Z..G40 T0. M9
M01[/QUOTE]

actually i leave out G54 when i didnt call a diff offset, because standard on our pumas the G54 is modal.
 
The program looks fine, I see nothing that should mess up your speed.
There is a guy at Daewoo, his name is Kaspar, I am sure he can help you.
Why don't you give him a call.
I just made a 40" part on a different machine, but the same control for a shop in Detroit and we had no problem.
The only thing different in the program was no G0 with the tool call, so it was T0101 by itself.
I have no clue if that has anything to do with it, but you might try it.
Do you know what the minimum RPM for your machine is?
The best of luck: Heinz.
www.doccnc.com

Minimum programmable speed is 1 RPM that goes for Puma 230-Puma 240-Puma 350-Puma 400 and Puma 700
 
Cuda how is the backlash on your machine when miling with a C-axis?
I found that the pumas with a gearbox are having a big backlash when milling circular on bigger diameters.
 
I'd be getting the parameter manual out and going through how its set up. It sounds like mightbe a simple way of incorrect diameter/ radius setup in the parameters.
 
This is the way I program this sequence:

T0101
M41
G97 M3 S25
G0 X18.5 Z.04 M8
G50 S300
G96 S125
WORK
G97 (sometimes I add S value here)
M9
T0100
G0 Z.04
X20 Z12.
M1


I think Alphonso nailed it there with the G50
However will your control will take a G1000 to make sure the spindle is at the correct RPM before the tool re-engages after a rapid move? Ive noticed this seems to be my number one cause of insert failure in the past. Other wise you could always use a G4 after each rapid.
 
I think Alphonso nailed it there with the G50
However will your control will take a G1000 to make sure the spindle is at the correct RPM before the tool re-engages after a rapid move? Ive noticed this seems to be my number one cause of insert failure in the past. Other wise you could always use a G4 after each rapid.

Sorry, but I don't see how limiting max rpm to 300 is going to help with the machine not running less than 50 rpm with a G96 block. I second the opinion to call Kasper. He is a nice guy who knows his machines.
 
Sorry, but I don't see how limiting max rpm to 300 is going to help with the machine not running less than 50 rpm with a G96 block. I second the opinion to call Kasper. He is a nice guy who knows his machines.

I use the G50 S "whatever" as a safety device to prevent over-speeding the spindle. Has nothing to do with minimum spindle speed.

Not familiar with a 21i control. 0TC has a parameter (0551) for "minimum spindle speed in G96", enter a value. Also has a parameter (0556) for max spindle speed in G96/G97 SCLMP (spindle speed clamp), enter a value.
 
I just changed #3771 from 50 to 5. CCS min (Fanuc 21it)
So minimum is 5 now, with 0 unlimited is asumed, so do anything above zero!
BTW turning at zero rpm would be silly also.
I dont think the drive will overheat, because in the Doosans the torque, drive heat, powerconsumption and whatsmore are used to caulculate general motorload.
And if it overheats, it will trip out anyway.
 








 
Back
Top