# Machsupport Forum

## Mach Discussion => General Mach Discussion => Topic started by: sml on April 30, 2010, 07:56:37 AM

Title: Cutting speed
Post by: sml on April 30, 2010, 07:56:37 AM
Hi
Can anyone tell me:
How calculate the cutting speed and rapid travels for cnc machines?
for example many milling machine have 24m/min speed for rapid travels and 1-10m/min for cutting speed.
Can i also use more than of 10m/min for cutting speed or not? Why?
Thank you
SML
Title: Re: Cutting speed
Post by: ger21 on April 30, 2010, 11:47:30 AM
Depends what you are cutting. We cut wood at 19M/min.
Title: Re: Cutting speed
Post by: Mattw on April 30, 2010, 01:22:33 PM
The tool you are using should provide recommended cutting speeds and chip loads.  Exercize some google-fu and you'll find a wealth of information on how to calculate rpm and feed rate for any particular tool.

Good luck.
Title: Re: Cutting speed
Post by: sml on April 30, 2010, 03:00:24 PM
Hi all my friend
Thank you for your answer but my basic question was for how calculate the maximum rapid travels and feed rate for any servo motor ?
Why some cnc machine say the rapid travels is 24m/min and feed rate is 1-8 m/min and in some machine say rapid travels is 24m/min and 1-10 m/min feed rate.
What is formulas is use for difference between rapid travels and feed rate?
Thank you
Title: Re: Cutting speed
Post by: Hood on April 30, 2010, 03:23:48 PM
On commercial controls I believe the control has  two different  following error limits, one for Rapids the other for Feeds.
Feeds obviously have to be accurate but the rapids dont have to be so accurate so often they have a larger following error for them allowing a faster rapid speed.
With Mach you  dont have that so your rapid will be your max feed. It will depend on your motors and drives how accurate things are at the max speed, some drives you can set the following error to what you want, others its fixed.

Hood
Title: Re: Cutting speed
Post by: sml on April 30, 2010, 03:34:21 PM
Hi Hood
Does the centroid software like mach software for rapid equal with max feed ?
Title: Re: Cutting speed
Post by: Hood on April 30, 2010, 05:03:04 PM
I am afraid I know nothing about the Centroid software.
Hood
Title: Re: Cutting speed
Post by: cjmerlin on April 30, 2010, 06:56:11 PM
Rapid feed is as fast as the machine will jog without losing position. Max cutting feed rate will depend on the maxium spinde speed for the cutter in use. For example my mill has a maxium spindle speed of 1750 rpm so even when using cutters that can happlily run at 10,000rpm I have to limit my feed rate to get the correct chip load for the cutter so it's slow feed rates for me until I redress the mill's lack of spindle rpm.