Cutting power calculator

Turning 1045 steel 3 mm deep at 0.25 mm/rev and 200 m/min on a 60 mm bar takes 7.5 kW at the motor and 54 N·m at the spindle by Sandvik’s figures; ISCAR’s give 6.4 kW. Choose the material and the maker whose specific cutting force to use, enter the cut and your spindle’s power, and see whether the machine will pull it.

The drawing shows the chip to scale and the power against the spindle’s rating; the table loads any material into it.

Cut

TurningMilling

kc from

SandvikISCAR

Material

Cutting speed vc

Diameter cut

Depth of cut ap

Feed f

Entering angle κr

Rake angle γ0

Spindle power

Efficiency η

Power at the motor

Of the spindle's power: 50%
Net power at the edge Pc
Specific cutting force kc
Chip thickness h
Metal removal rate Q
Spindle speed
Torque at the spindle
Cutting force Fc
ISCAR's kc gives: 6.36 kW (−15 %)

How it’s calculated

$k_{c} = k_{c 1} h^{- m_{c}} (1 - \frac{γ _{0}}{100})$ with h = f·sin κr; P_c = v_c·a_p·f·k_c / 60 000 kW, Q = v_c·a_p·f cm³/min, M = P_c·30 000 / (π·n). The motor gives P_c / η. Here: k_c = 1700 × 0.249^−0.25 × (1 − 0/100) = 2406 N/mm², P_c = 6.02 kW, / 0.8 = 7.52 kW.

Group	Material	Sandvik row	Sandvik kc1	Sandvik mc	ISCAR row	ISCAR kc1	ISCAR mc	kc at this h (Sandvik)
P	Low-carbon steel, ≤ 0.25 % C, annealed (1018, S235)	P1.1.Z.AN 125 HB	1500	0.25	group 1	1350	0.21	2123
P	Medium-carbon steel, 0.25–0.55 % C, annealed (1045, C45)	P1.2.Z.AN 190 HB	1700	0.25	group 2	1500	0.22	2406
P	Medium-carbon steel, hardened and tempered	P1.2.Z.HT 210 HB	1820	0.25	group 3	1675	0.24	2576
P	High-carbon steel, > 0.55 % C, annealed	P1.3.Z.AN 190 HB	1750	0.25	group 4	1700	0.24	2477
P	Free-cutting steel, annealed (12L14, 11SMnPb30)	P1.4.Z.AN 220 HB	1180	0.25	—	—	—	1670
P	Low-alloy steel, 0.25–0.55 % C, annealed (4140, 42CrMo4)	P2.2.Z.AN 240 HB	1950	0.25	group 6	1775	0.24	2760
P	Low-alloy steel, hardened and tempered (4140 pre-hardened)	P2.5.Z.HT 330 HB	2000	0.25	group 9	1800	0.24	2831
P	High-alloy and tool steel, annealed (D2, H13)	P3.0.Z.AN 200 HB	1950	0.25	group 10	2450	0.23	2760
P	High-alloy and tool steel, hardened and tempered	P3.0.Z.HT 380 HB	3100	0.25	group 11	2500	0.23	4388
P	Ferritic and martensitic stainless, annealed (410, 416, 420)	P5.0.Z.AN 200 HB	1800	0.21	group 12	1875	0.21	2410
P	Precipitation-hardened stainless (17-4PH)	P5.0.Z.PH 330 HB	2800	0.21	—	—	—	3749
M	Austenitic stainless (304, 316)	M1.0.Z.AQ 200 HB	2000	0.21	group 14	2150	0.2	2678
M	Duplex stainless, < 60 % ferrite (2205)	M3.2.Z.AQ 260 HB	2400	0.21	group 14	2150	0.2	3214
K	Grey cast iron, low tensile	K2.1.C.UT 180 HB	900	0.28	group 15	1150	0.2	1328
K	Grey cast iron, high tensile	K2.2.C.UT 245 HB	1100	0.28	group 16	1350	0.28	1623
K	Nodular (ductile) iron, ferritic	K3.1.C.UT 155 HB	870	0.28	group 17	1225	0.25	1284
K	Nodular (ductile) iron, pearlitic	K3.3.C.UT 265 HB	1440	0.28	group 18	1350	0.28	2125
N	Wrought aluminium, aged (6061-T6, 7075-T6)	N1.2.Z.AG 100 HB	650	0.25	group 22	800	0.25	920
N	Cast aluminium, ≤ 13 % Si	N1.3.C.UT 75 HB	600	0.25	group 23	700	0.25	849
N	Free-cutting brass, > 1 % Pb (CZ121, C36000)	N3.3.U.UT 110 HB	550	0.25	group 26	700	0.27	779
S	Nickel alloy, annealed	S2.0.Z.AN 250 HB	2650	0.25	group 33	3300	0.24	3751
S	Nickel alloy, aged (Inconel 718)	S2.0.Z.AG 350 HB	2900	0.25	group 34	3300	0.24	4105
S	Titanium, commercially pure	S4.1.Z.UT 200 HB	1300	0.23	group 36	1700	0.23	1790
H	Hardened steel, 50 HRC	H1.1.Z.HA 50 HRC	3090	0.25	—	—	—	4374
H	Hardened steel, 55 HRC	H1.2.Z.HA 55 HRC	3690	0.25	group 38	4600	—	5223
H	Hardened steel, 60 HRC	H1.3.Z.HA 60 HRC	4330	0.25	group 39	4700	—	6129

Why do two tool makers give different powers?

Each maker measures kc on its own tools and its own test bars, and groups the materials its own way. For the same steel the figures can differ by a third, so treat the power as an estimate and leave a margin. The calculator shows the other maker’s figure beside the one you chose, so the spread is in front of you.