Quick CNC question about M08 code...

[bjbaker]

On a machining center typically, when do you turn on / off the coolant pump? Does it need to be off before reaching the tool changer, on before leaving it?

Any suggestions / methods are appreciated. thanks.

 

[bjbaker]

HAAS controls, if that makes a difference...

 

[BobM3]

I don't have a Haas but on mine I don't explicitly tell the coolant to turn on/off. The tool change command (M06) automatically turns it off/on before and after the tool change.

 

[larrylcoyle]

My machine does the same thing. This is usually automatically built into the controller of your machine.

Larry

Larry Coyle
Managing Partner
Cylinder Head Engineering, LLC
CNC Porting
De Soto, KS 66018

 

[saberblue]

From a coolant point of view there are advantages and disadvantages to controlling fluid flow buy turning the pump on and off and you should at least think them through before you change what you are currently doing --

turning the pump on and off
advantages = less foam in the tank - more quiescent time for fines to settle or be filtered
disadvantages + there may be a lag in time between when the machine starts to cut and the fluid reaches the point of cut leading to tool failure from thermal shocking -- more wear and tear on the coolant pump etc.

shutting off fluid flow with a valve
advantage = fluid is instantly available - less chance of air being captured in the coolant delivery system
disadvantage = dead heading the pump can cause foam in the tank == can raise the operating temperature of the working solution can be hard on rotary unions and seals



A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

 

[dicer]

It doesn't matter if you want to leave it on during the tool change. If you have through the spindle coolant its on the taper at all times. No you wouldn't want to leave on the through the spindle coolant.
Most normally you turn it off before the G91G28Z0 move.
Some do this right after the cuts finished.

G1Z2.F100.M8;
G91G28Z0;
G91G28X0Y0;
Tool change or M30
and on and on

 

[jpietrowiak]

Some CNC machines and dealers add on cheaper high pressure coolant systems onto machines that are not designed for high pressure which can cause problems in itself. But if the high pressure coolant is tied to M8/M9 then you should try to shut it off before hand. If the coolant has a delay as a pump winds down and does not dump remaining pressure to tank as some systems do, then this is also a good practice to command the coolant to shut off earlier rather then later instead of waiting for the machine to do it automatically. One way to tell if there could be issues with your system setup is if you have problems with low drawbar clamp force frequently and are needing them rebuilt more often then some of the other CNC machines. This is the typical problem that happens with machining centers.

Jamey
Visit

http://www.cncalarms.com

for CNC related alarms and to lookup troubleshooting tips.

 

[highspeedmachinist]

HAAS will shut it off as you go to tool change. Even during set up, when your aiming the coolant and are in a rotate forward/rotate reverse, it shuts off and then back on upon tool rotation. High pressure through the spindle is an entirely different M-code and would be a seals issue in leaving the coolant on and or turning the through the spindle coolant with a solid/blocked tool holder or cutter.

Most posts can be developed to deal with this issue. Coolant foam is more an issue of an anti-foaming agent in the coolant itself.