CNC Machinist Calculator UltraG96 Constant surface speed / Constant surface speed on
Fanuc G-code · Mill, Lathe
On mills: Constant surface speed
S is the surface speed in feet per minute in G20. The control changes RPM as the cutting diameter changes. Rare on mills, used with facing heads or turning on mill turn machines.
Verify on your machine. This entry could not be fully checked against the maker manual. Check your machine manual before you run it.
Format
Addresses
| Address | What it does |
|---|---|
S | Surface speed, feet per minute in G20 |
How it works
Modal, group 13. Cancel with G97.
Example program
G96 S500 M03 (500 SFM)
G01 X0. F.005 (FACE IN)
G97 S1000 (BACK TO FIXED RPM)
Example is in inch. Check offsets and clearances first.
Watch out for
- This is an option on machining centers. The axis used for the diameter is set by a parameter.
- Clamp the maximum RPM before G96, or RPM can run away near the center. On mills the clamp is often G92 S.
- Most mill work uses G97 with a fixed RPM.
On lathes: Constant surface speed on
S becomes surface feet per minute in inch mode. The control raises RPM as X gets smaller to keep the cutting speed constant.
Format
Addresses
| Address | What it does |
|---|---|
S | Surface speed, feet per minute in G20 or meters per minute in G21 |
How it works
Modal, group 02. Cancel with G97.
Example program
G96 S500 M03 (CSS 500 SFM)
G00 X2. Z.1 M08 (APPROACH)
Example is in inch. Check offsets and clearances first.
Watch out for
- Set G50 S max RPM first. Near X0 the RPM climbs to the limit.
- Do not thread or drill on center in G96. Use G97.
Related codes
G96 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Haas NGC | Constant surface speed on |
| Mazak (EIA) | Constant surface speed |
| Okuma OSP | Constant surface speed on |
| Mitsubishi M70 M80 | Constant surface speed on |
| Siemens 840D 828D | Constant cutting speed |
| Fagor 8055 8065 | Constant feed at cutting point (mill) |
| LinuxCNC Tormach | Constant surface speed |
| Mach3 Mach4 | Constant surface speed, Mach4 |
| Centroid CNC12 Acorn | Constant surface speed |
| Swiss (Citizen Star) | Constant surface speed |
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