What SFM should I use for O2 Tool Steel?

Lakeshore Carbide – General Purpose End Mill Speeds & Feeds lists 150–400 SFM for carbide end mills in the "Steels – Tool Steel" row. Start at the low end and adjust for your machine.

What chip load for a 1/2" end mill in O2 Tool Steel?

The published range for 3/8–1/2" carbide end mills is .0012–.0025" per tooth. At 150 SFM a 3-flute 1/2" end mill runs about 1146 RPM and 4.1 IPM.

Are these values for HSS tools, drilling or turning?

The end mill chart covers carbide end mills. The "Speeds by tool material" table adds published HSS, turning-insert and drilling rows for O2 Tool Steel where a source lists them (LittleMachineShop, Sandvik Coromant).

O2 Tool Steel Speeds and Feeds (Milling, Drilling, Turning)

Carbide end mills in O2 Tool Steel: 150–400 SFM. Also called AISI O2. Chart row used: “Steels – Tool Steel” (Annealed).

Starting point: carbide end mills

RPM and IPM use the low end of the published range (150 SFM and the lowest chip load for each diameter range). RPM = SFM × 12 ÷ (π × D); IPM = RPM × flutes × chip load.

O2 Tool Steel — inch end mills
Diameter	Chip load (in/tooth)	RPM	IPM · 2 flute	IPM · 3 flute
1/8"	.0004	4,584	3.7	5.5
1/4"	.0005	2,292	2.3	3.4
3/8"	.0010	1,528	3.1	4.6
1/2"	.0012	1,146	2.8	4.1
3/4"	.0018	764	2.8	4.1
1"	.0020	573	2.3	3.4

O2 Tool Steel — metric end mills (inch chip-load range the size falls in)
Diameter	Chip load (in/tooth)	RPM	IPM · 2 flute	IPM · 3 flute
3 mm	.0004	4,851	3.9	5.8
6 mm	.0005	2,426	2.4	3.6
10 mm	.0012	1,455	3.5	5.2
12 mm	.0012	1,213	2.9	4.4
16 mm	.0018	910	3.3	4.9
20 mm	.0020	728	2.9	4.4

Full published chip-load ranges

1/32-1/8": .0004–.0010"
1/8-1/4": .0005–.0015"
1/4-3/8": .0010–.0020"
3/8-1/2": .0012–.0025"
1/2-3/4": .0018–.0035"
3/4-1": .0020–.0045"

Calculator — prefilled for O2 Tool Steel

Results for Milling

Spindle RPM: 1,146
Feed: 5.5 IPM
Chip load: 0.0011 in

MRR: 0.21 in³/min
Power: — HP
Torque: — lbf·ft
Programmed fz: 0.0012 in
Actual SFM: 150
Spindle use: 10%

Pick a material in the library below to estimate spindle power and torque.

Operation Type

Milling

Turning

Material library

Auto-adjust cutting data

Material & condition

Cutting tool material

Tool coating

Tool & coating guidance

Grade, edge geometry and coating determine usable cutting data. Sharp polished edges can suit nonferrous work; substrate and geometry still govern. Coated vs uncoated carbide changes turning data only; no coating speed multiplier is inferred.

Tool & cut parameters

Manual values

SFM (Surface Feet/Min)

Cutter Diameter (in)

Number of Flutes

Axial depth of cut (in)

Feed per Tooth (in)

Machine RPM limit

Chip thinning & cutter body

Cutter body

Chip-thinning compensation

Radial engagement (% of diameter)

Entering angle KAPR (°)

Radial factor ×1.09Angle factor ×1.00Programmed fz 0.0012 inMax chip hex 0.0011 in

Fixed-angle peripheral estimate: hex = fz × radial factor × sin(KAPR). No radial correction at ≥50% engagement. Not a centered face-milling or ball-nose model. Sandvik geometry reference

Insert styles, guidelines & formulas

RPM = (SFM × 12) / (π × D) | Feed = RPM × programmed fz × effective zc | MRR = WOC × DOC × feed | HP = Kp × C × MRR × 1.1 ÷ 0.8 (Machinery's Handbook)

Milling Insert Styles

Square (SEMT/SNMG)

General purpose, 90° lead angle

Round (RPMW/RCKT)

Ramping, 3D contouring, high feed

Triangular (TPMX)

Light cuts, finishing

Octagonal (ONMU)

Face milling; HFM suitability is body-specific

Milling Guidelines

Start at 70% of max SFM, increase gradually
Chip load too low → rubbing & heat buildup
Use climb milling when machine rigidity allows
Radial engagement >50% → reduce feed per tooth
Round inserts: best for ramp-in and 3D surfaces

Open in the full calculator workspace

Speeds by tool material

Published starting ranges for O2 Tool Steel by operation and tool material. Rows marked * are estimates.

O2 Tool Steel — speeds by tool material
Operation	Tool	SFM	Feed	Source row
milling	HSS *	50	0.0012–0.0025 in/tooth	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
milling	Cobalt HSS (M35/M42) *	50	0.0012–0.0025 in/tooth	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
milling	Solid carbide end mill	150–400	0.0012–0.0025 in/tooth	Lakeshore Carbide · Steels – Tool Steel
milling	Coated carbide (GC4230)	420–630	0.0040–0.0120 in hex	Sandvik milling (large engagement) · CMC 03.11 High-alloy steel and tool steel, annealed
milling	Cermet (CT530)	610–740	0.0040–0.0080 in hex	Sandvik milling (large engagement) · CMC 03.11 High-alloy steel and tool steel, annealed
turning	HSS	125	0.0040 in/rev	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
turning	Cobalt HSS (M35/M42) *	125	0.0040 in/rev	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
turning	Uncoated carbide	590	0.0040 in/rev	LittleMachineShop carbide turning · Cold work, oil hardening tool steel
turning	Coated carbide (GC4325)	500–980	0.0040–0.0310 in/rev	Sandvik turning · CMC 03.11 High-alloy steel and tool steel, annealed
turning	Cermet (CT5015)	820–1300	0.0020–0.0080 in/rev	Sandvik turning · CMC 03.11 High-alloy steel and tool steel, annealed
drilling	HSS	45	—	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
drilling	Cobalt HSS (M35/M42) *	45	—	LittleMachineShop · Cold work, oil hardening tool steel (O1, O2, O6, O7)
drilling	Coated carbide (4234)	195–330	0.0047–0.0130 in/rev	Sandvik CoroDrill 870 · CMC 03.11 High-alloy steel and tool steel, annealed

Machinist tips

Chip thinning: At light radial engagement (under half the cutter diameter) the real chip is thinner than the feed per tooth. Raise the feed to keep the chip at the chart value, or the tool rubs and wears.
Climb vs conventional: On a rigid CNC, climb mill so each tooth starts thick and exits thin. Use conventional milling on machines with backlash or on hard scale skins.
Check hardness first: These values are for annealed stock. Hardened tool steel needs hard-milling tools and the maker's data for that hardness.

Common questions

What SFM should I use for O2 Tool Steel?: Lakeshore Carbide – General Purpose End Mill Speeds & Feeds lists 150–400 SFM for carbide end mills in the "Steels – Tool Steel" row. Start at the low end and adjust for your machine.
What chip load for a 1/2" end mill in O2 Tool Steel?: The published range for 3/8–1/2" carbide end mills is .0012–.0025" per tooth. At 150 SFM a 3-flute 1/2" end mill runs about 1146 RPM and 4.1 IPM.
Are these values for HSS tools, drilling or turning?: The end mill chart covers carbide end mills. The "Speeds by tool material" table adds published HSS, turning-insert and drilling rows for O2 Tool Steel where a source lists them (LittleMachineShop, Sandvik Coromant).

W1 Tool Steel speeds and feeds S7 Tool Steel speeds and feeds H11 Tool Steel speeds and feeds