A carbide end mill starts at about 250–450 SFM in 1018 steel, 150–250 SFM in 304 stainless and 600–1,500 SFM in 6061 aluminium; HSS starts at roughly a quarter to a half of those speeds.

This chart gives conservative starting surface speeds for 17 common workpiece materials, for HSS and coated carbide, in milling, drilling and turning. Below it are starting chip loads for end mills by diameter, drill feed per revolution by drill size, and turning feed per revolution for roughing and finishing. Read across from your material to the operation and tool, start near the middle of the range, then turn the speed into RPM with the formula further down. Switch between inch (SFM, in) and metric (m/min, mm) with the buttons above the tables. The ISO column (P, M, K, N, S, H) matches the colour codes on insert and tool boxes. These are starting points only: adjust them from your tool maker's catalogue and from what you see and hear at the machine.

Want RPM and feed rates for your own tools? The Speeds & Feeds Chart Builder uses these same numbers to build a printable table for your end mills, drills or bar sizes, with your machine's maximum RPM.

Surface speed chart (SFM and m/min)

Starting cutting speed at the tool's outside diameter (milling and drilling) or at the workpiece diameter (turning). Values in surface feet per minute (SFM).Values in metres per minute (Vc, m/min), converted from SFM and rounded to the nearest 5. “n/r” means not recommended.

MaterialISOTypical hardnessMillingDrillingTurning
HSSSFMm/minCarbideSFMm/minHSSSFMm/minCarbideSFMm/minHSSSFMm/minCarbideSFMm/min
Low-carbon steel1018, 1020, EN3 / S235P120–160 HB80–12024–37250–45075–13510833476145100–15030–46400–600120–185
Medium-carbon steel1045, EN8 / C45P170–220 HB60–9018–27200–35060–10555–8017–24180–30055–9080–12024–37300–48090–145
Alloy steel, annealed4140, 42CrMo4 / EN19P180–230 HB50–8015–24180–30055–9045–7014–21150–25046–7570–10021–30260–40080–120
Tool steel, annealedO1, A2, D2, H13P200–250 HB35–6011–18120–20037–6030–509–15100–18030–5550–8015–24180–30055–90
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP28–32 HRC30–509–15100–18030–5525–458–1490–16027–4940–6012–18150–24046–75
Stainless steel, free-machining303, 416M160–230 HB60–10018–30200–35060–10550–8015–24180–26055–8080–12024–37300–45090–135
Stainless steel, austenitic304, 316, 316LM150–220 HB40–7012–21150–25046–7543131805560–9018–27220–35065–105
Grey cast ironClass 30–40, GG25 / EN-GJL-250K180–230 HB60–10018–30200–35060–10550–8015–24150–28046–8570–11021–34250–40075–120
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N60–150 HB250–50075–150600–1500185–455200–30060–90400–800120–245300–60090–185800–1600245–490
Aluminium, cast / high-siliconA356, A380, LM25, A390N70–120 HB150–30046–90400–1000120–305150–25046–75300–60090–185200–40060–120600–1200185–365
Brass, free-cuttingC360, CZ121N80–150 HB200–35060–105500–1000150–305150–30046–90300–60090–185250–40075–120600–1200185–365
BronzeC932 bearing bronze, phosphor bronzeN60–150 HB80–15024–46250–45075–13560–12018–37150–30046–90100–16030–49300–60090–185
CopperC110, C101 (pure copper)N40–90 HB100–20030–60300–60090–18570–15021–46150–35046–105100–20030–60300–70090–215
PlasticsAcetal (POM, Delrin), nylon (PA)NSoft300–60090–185600–1200185–365150–30046–90300–60090–185300–60090–185600–1200185–365
Titanium alloyTi-6Al-4V (Grade 5)S30–36 HRC25–458–1480–15024–4620–356–1160–12018–3730–509–15100–18030–55
Nickel alloyInconel 718S36–44 HRC (aged)15–255–850–9015–2710–203–630–609–1815–255–850–10015–30
Hardened steelThrough-hardened tool and alloy steelH45–55 HRCn/r80–16024–49n/r50–10015–30n/r100–20030–60

Carbide = coated solid carbide end mills and drills, and coated carbide turning inserts. HSS = high-speed steel (cobalt HSS can run about 10% faster). Start D2, 316 and cast high-silicon aluminium at the low end.

End mill chip load by diameter

Starting feed per tooth (chip load, fz) for solid carbide end mills side milling or slotting at up to about 1× diameter depth. Use the same range for HSS end mills but start at the low end. For light radial cuts (under about 30% of the diameter) the chip gets thinner, so you can raise the feed: see the Chip Thinning Calculator.

MaterialISO1/8"3/16"1/4"5/16"3/8"1/2"5/8"3/4"1"
Low-carbon steel1018, 1020, EN3 / S235P0.0005–0.00100.0008–0.00150.0010–0.00200.0013–0.00240.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.0060
Medium-carbon steel1045, EN8 / C45P0.0005–0.00100.0008–0.00150.0010–0.00200.0013–0.00240.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.0060
Alloy steel, annealed4140, 42CrMo4 / EN19P0.0005–0.00100.0008–0.00150.0010–0.00200.0013–0.00240.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.0060
Tool steel, annealedO1, A2, D2, H13P0.0004–0.00080.0006–0.00120.0008–0.00150.0010–0.00180.0012–0.00220.0015–0.00280.0018–0.00320.0022–0.00370.0028–0.0045
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP0.0004–0.00080.0006–0.00120.0008–0.00150.0010–0.00180.0012–0.00220.0015–0.00280.0018–0.00320.0022–0.00370.0028–0.0045
Stainless steel, free-machining303, 416M0.0005–0.00100.0008–0.00150.0010–0.00200.0013–0.00240.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.0060
Stainless steel, austenitic304, 316, 316LM0.0004–0.00080.0006–0.00120.0008–0.00150.0010–0.00180.0012–0.00220.0015–0.00280.0018–0.00320.0022–0.00370.0028–0.0045
Grey cast ironClass 30–40, GG25 / EN-GJL-250K0.0005–0.00100.0008–0.00150.0010–0.00200.0013–0.00240.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.0060
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N0.0010–0.00200.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.00600.0041–0.00700.0048–0.00800.0060–0.0100
Aluminium, cast / high-siliconA356, A380, LM25, A390N0.0008–0.00150.0012–0.00230.0015–0.00300.0018–0.00340.0020–0.00380.0025–0.00450.0029–0.00510.0033–0.00580.0040–0.0070
Brass, free-cuttingC360, CZ121N0.0008–0.00150.0012–0.00230.0015–0.00300.0018–0.00340.0020–0.00380.0025–0.00450.0029–0.00510.0033–0.00580.0040–0.0070
BronzeC932 bearing bronze, phosphor bronzeN0.0008–0.00150.0012–0.00230.0015–0.00300.0018–0.00340.0020–0.00380.0025–0.00450.0029–0.00510.0033–0.00580.0040–0.0070
CopperC110, C101 (pure copper)N0.0008–0.00150.0012–0.00230.0015–0.00300.0018–0.00340.0020–0.00380.0025–0.00450.0029–0.00510.0033–0.00580.0040–0.0070
PlasticsAcetal (POM, Delrin), nylon (PA)N0.0010–0.00200.0015–0.00280.0020–0.00350.0024–0.00410.0028–0.00480.0035–0.00600.0041–0.00700.0048–0.00800.0060–0.0100
Titanium alloyTi-6Al-4V (Grade 5)S0.0003–0.00060.0005–0.00090.0006–0.00120.0008–0.00150.0009–0.00170.0012–0.00220.0015–0.00250.0017–0.00290.0022–0.0035
Nickel alloyInconel 718S0.0003–0.00060.0005–0.00090.0006–0.00120.0008–0.00150.0009–0.00170.0012–0.00220.0015–0.00250.0017–0.00290.0022–0.0035
Hardened steelThrough-hardened tool and alloy steelH0.0002–0.00040.0003–0.00060.0004–0.00080.0005–0.00100.0006–0.00120.0008–0.00150.0010–0.00180.0012–0.00200.0015–0.0025

Inches per tooth. Diameters in inches.

MaterialISO3 mm4 mm5 mm6 mm8 mm10 mm12 mm16 mm20 mm25 mm
Low-carbon steel1018, 1020, EN3 / S235P0.012–0.0240.016–0.0320.020–0.0400.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.088–0.150
Medium-carbon steel1045, EN8 / C45P0.012–0.0240.016–0.0320.020–0.0400.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.088–0.150
Alloy steel, annealed4140, 42CrMo4 / EN19P0.012–0.0240.016–0.0320.020–0.0400.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.088–0.150
Tool steel, annealedO1, A2, D2, H13P0.010–0.0190.013–0.0250.016–0.0310.019–0.0360.025–0.0470.031–0.0570.036–0.0670.047–0.0820.057–0.0960.070–0.113
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP0.010–0.0190.013–0.0250.016–0.0310.019–0.0360.025–0.0470.031–0.0570.036–0.0670.047–0.0820.057–0.0960.070–0.113
Stainless steel, free-machining303, 416M0.012–0.0240.016–0.0320.020–0.0400.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.088–0.150
Stainless steel, austenitic304, 316, 316LM0.010–0.0190.013–0.0250.016–0.0310.019–0.0360.025–0.0470.031–0.0570.036–0.0670.047–0.0820.057–0.0960.070–0.113
Grey cast ironClass 30–40, GG25 / EN-GJL-250K0.012–0.0240.016–0.0320.020–0.0400.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.088–0.150
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N0.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.085–0.1450.105–0.1790.125–0.2110.150–0.251
Aluminium, cast / high-siliconA356, A380, LM25, A390N0.019–0.0360.025–0.0480.031–0.0600.036–0.0720.045–0.0860.053–0.0980.061–0.1100.073–0.1310.085–0.1510.100–0.176
Brass, free-cuttingC360, CZ121N0.019–0.0360.025–0.0480.031–0.0600.036–0.0720.045–0.0860.053–0.0980.061–0.1100.073–0.1310.085–0.1510.100–0.176
BronzeC932 bearing bronze, phosphor bronzeN0.019–0.0360.025–0.0480.031–0.0600.036–0.0720.045–0.0860.053–0.0980.061–0.1100.073–0.1310.085–0.1510.100–0.176
CopperC110, C101 (pure copper)N0.019–0.0360.025–0.0480.031–0.0600.036–0.0720.045–0.0860.053–0.0980.061–0.1100.073–0.1310.085–0.1510.100–0.176
PlasticsAcetal (POM, Delrin), nylon (PA)N0.024–0.0480.032–0.0610.040–0.0730.048–0.0850.061–0.1050.073–0.1250.085–0.1450.105–0.1790.125–0.2110.150–0.251
Titanium alloyTi-6Al-4V (Grade 5)S0.007–0.0140.010–0.0190.012–0.0240.014–0.0290.019–0.0370.024–0.0450.029–0.0530.037–0.0640.045–0.0750.055–0.088
Nickel alloyInconel 718S0.007–0.0140.010–0.0190.012–0.0240.014–0.0290.019–0.0370.024–0.0450.029–0.0530.037–0.0640.045–0.0750.055–0.088
Hardened steelThrough-hardened tool and alloy steelH0.005–0.0100.006–0.0130.008–0.0160.010–0.0190.013–0.0250.016–0.0310.019–0.0360.025–0.0450.031–0.0530.038–0.063

Millimetres per tooth. Diameters in millimetres.

Drill feed per revolution

Mild steel and stainless steel use our own shop-proven drill chart below: one feed per revolution for each drill size from 1 to 16 mm, plus the cutting speed (Vc) to run it at, for HSS and solid carbide drills. Every other material uses a starting feed worked out as a percentage of drill diameter (the shop rule of 1% to 2% of D for steel). Peck or use a through-coolant drill once the hole is deeper than about 3 to 4 diameters.

Shop drill chart: mild steel and stainless steel

Feed per revolution for standard-length twist drills. The bottom row is the cutting speed: RPM = Vc × 318 ÷ D (318 is 1000 ÷ π, D in mm). For example, a 10 mm carbide drill in mild steel runs at 145 × 318 ÷ 10 = 4,611 RPM, and at 0.315 mm/rev that is 4,611 × 0.315 = 1,452 mm/min.

Drill diamminHSS drillCarbide drill
Mild steelmm/revin/revStainlessmm/revin/revMild steelmm/revin/revStainlessmm/revin/rev
10.03940.020.00080.020.00080.060.00240.030.0012
20.07870.060.00240.050.00200.080.00310.050.0020
30.11810.100.00390.060.00240.1250.00490.080.0031
40.15750.110.00430.100.00390.160.00630.100.0039
50.19690.120.00470.120.00470.160.00630.100.0039
60.23620.130.00510.140.00550.200.00790.1250.0049
70.27560.150.00590.160.00630.220.00870.140.0055
80.31500.170.00670.180.00710.250.00980.160.0063
90.35430.190.00750.200.00790.280.01100.180.0071
100.39370.200.00790.220.00870.3150.01240.200.0079
110.43310.220.00870.240.00940.3150.01240.200.0079
120.47240.240.00940.260.01020.3150.01240.200.0079
130.51180.260.01020.280.01100.340.01340.200.0079
140.55120.260.01020.280.01100.360.01420.220.0087
150.59060.270.01060.290.01140.380.01500.240.0094
160.62990.280.01100.300.01180.400.01570.250.0098
Vc (m/min)SFM33108134314547655180

Machinist Central shop data for HSS and solid carbide drills in mild steel (1018, 1020, EN3 / S235) and austenitic stainless (304, 316). Above 16 mm the general tables hold the 16 mm feed (marked *). In the general tables below these two materials have one row for each drill type.

All materials

MaterialISO1/16"1/8"3/16"1/4"5/16"3/8"1/2"5/8"3/4"1"
Low-carbon steel, HSS drill1018, 1020, EN3 / S235 · shop chartP0.00170.00400.00460.00540.00660.00770.01000.01100.0110*0.0110*
Low-carbon steel, Carbide drill1018, 1020, EN3 / S235 · shop chartP0.00280.00520.00630.00810.00980.01170.01310.01560.0157*0.0157*
Medium-carbon steel1045, EN8 / C45P0.0006–0.00110.0013–0.00230.0019–0.00340.0025–0.00450.0031–0.00560.0038–0.00680.0050–0.00900.0063–0.01130.0075–0.01350.0100–0.0180
Alloy steel, annealed4140, 42CrMo4 / EN19P0.0006–0.00110.0013–0.00230.0019–0.00340.0025–0.00450.0031–0.00560.0038–0.00680.0050–0.00900.0063–0.01130.0075–0.01350.0100–0.0180
Tool steel, annealedO1, A2, D2, H13P0.0006–0.00110.0013–0.00230.0019–0.00340.0025–0.00450.0031–0.00560.0038–0.00680.0050–0.00900.0063–0.01130.0075–0.01350.0100–0.0180
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP0.0004–0.00090.0009–0.00180.0013–0.00260.0018–0.00350.0022–0.00440.0026–0.00530.0035–0.00700.0044–0.00880.0053–0.01050.0070–0.0140
Stainless steel, free-machining303, 416M0.0006–0.00110.0013–0.00230.0019–0.00340.0025–0.00450.0031–0.00560.0038–0.00680.0050–0.00900.0063–0.01130.0075–0.01350.0100–0.0180
Stainless steel, austenitic, HSS drill304, 316, 316L · shop chartM0.00150.00260.00450.00580.00700.00830.01080.01180.0118*0.0118*
Stainless steel, austenitic, Carbide drill304, 316, 316L · shop chartM0.00160.00330.00390.00510.00630.00750.00790.00980.0098*0.0098*
Grey cast ironClass 30–40, GG25 / EN-GJL-250K0.0006–0.00110.0013–0.00230.0019–0.00340.0025–0.00450.0031–0.00560.0038–0.00680.0050–0.00900.0063–0.01130.0075–0.01350.0100–0.0180
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N0.0009–0.00160.0019–0.00310.0028–0.00470.0038–0.00630.0047–0.00780.0056–0.00940.0075–0.01250.0094–0.01560.0113–0.01880.0150–0.0250
Aluminium, cast / high-siliconA356, A380, LM25, A390N0.0009–0.00160.0019–0.00310.0028–0.00470.0038–0.00630.0047–0.00780.0056–0.00940.0075–0.01250.0094–0.01560.0113–0.01880.0150–0.0250
Brass, free-cuttingC360, CZ121N0.0009–0.00160.0019–0.00310.0028–0.00470.0038–0.00630.0047–0.00780.0056–0.00940.0075–0.01250.0094–0.01560.0113–0.01880.0150–0.0250
BronzeC932 bearing bronze, phosphor bronzeN0.0006–0.00130.0013–0.00250.0019–0.00380.0025–0.00500.0031–0.00630.0038–0.00750.0050–0.01000.0063–0.01250.0075–0.01500.0100–0.0200
CopperC110, C101 (pure copper)N0.0006–0.00130.0013–0.00250.0019–0.00380.0025–0.00500.0031–0.00630.0038–0.00750.0050–0.01000.0063–0.01250.0075–0.01500.0100–0.0200
PlasticsAcetal (POM, Delrin), nylon (PA)N0.0009–0.00160.0019–0.00310.0028–0.00470.0038–0.00630.0047–0.00780.0056–0.00940.0075–0.01250.0094–0.01560.0113–0.01880.0150–0.0250
Titanium alloyTi-6Al-4V (Grade 5)S0.0004–0.00090.0009–0.00180.0013–0.00260.0018–0.00350.0022–0.00440.0026–0.00530.0035–0.00700.0044–0.00880.0053–0.01050.0070–0.0140
Nickel alloyInconel 718S0.0003–0.00060.0006–0.00130.0009–0.00190.0013–0.00250.0016–0.00310.0019–0.00380.0025–0.00500.0031–0.00630.0038–0.00750.0050–0.0100
Hardened steelThrough-hardened tool and alloy steelH0.0003–0.00060.0006–0.00130.0009–0.00190.0013–0.00250.0016–0.00310.0019–0.00380.0025–0.00500.0031–0.00630.0038–0.00750.0050–0.0100

Inches per revolution. Drill diameters in inches.

MaterialISO2 mm3 mm4 mm5 mm6 mm8 mm10 mm12 mm16 mm20 mm25 mm
Low-carbon steel, HSS drill1018, 1020, EN3 / S235 · shop chartP0.0600.1000.1100.1200.1300.1700.2000.2400.2800.280*0.280*
Low-carbon steel, Carbide drill1018, 1020, EN3 / S235 · shop chartP0.0800.1250.1600.1600.2000.2500.3150.3150.4000.400*0.400*
Medium-carbon steel1045, EN8 / C45P0.020–0.0360.030–0.0540.040–0.0720.050–0.0900.060–0.1080.080–0.1440.100–0.1800.120–0.2160.160–0.2880.200–0.3600.250–0.450
Alloy steel, annealed4140, 42CrMo4 / EN19P0.020–0.0360.030–0.0540.040–0.0720.050–0.0900.060–0.1080.080–0.1440.100–0.1800.120–0.2160.160–0.2880.200–0.3600.250–0.450
Tool steel, annealedO1, A2, D2, H13P0.020–0.0360.030–0.0540.040–0.0720.050–0.0900.060–0.1080.080–0.1440.100–0.1800.120–0.2160.160–0.2880.200–0.3600.250–0.450
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP0.014–0.0280.021–0.0420.028–0.0560.035–0.0700.042–0.0840.056–0.1120.070–0.1400.084–0.1680.112–0.2240.140–0.2800.175–0.350
Stainless steel, free-machining303, 416M0.020–0.0360.030–0.0540.040–0.0720.050–0.0900.060–0.1080.080–0.1440.100–0.1800.120–0.2160.160–0.2880.200–0.3600.250–0.450
Stainless steel, austenitic, HSS drill304, 316, 316L · shop chartM0.0500.0600.1000.1200.1400.1800.2200.2600.3000.300*0.300*
Stainless steel, austenitic, Carbide drill304, 316, 316L · shop chartM0.0500.0800.1000.1000.1250.1600.2000.2000.2500.250*0.250*
Grey cast ironClass 30–40, GG25 / EN-GJL-250K0.020–0.0360.030–0.0540.040–0.0720.050–0.0900.060–0.1080.080–0.1440.100–0.1800.120–0.2160.160–0.2880.200–0.3600.250–0.450
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N0.030–0.0500.045–0.0750.060–0.1000.075–0.1250.090–0.1500.120–0.2000.150–0.2500.180–0.3000.240–0.4000.300–0.5000.375–0.625
Aluminium, cast / high-siliconA356, A380, LM25, A390N0.030–0.0500.045–0.0750.060–0.1000.075–0.1250.090–0.1500.120–0.2000.150–0.2500.180–0.3000.240–0.4000.300–0.5000.375–0.625
Brass, free-cuttingC360, CZ121N0.030–0.0500.045–0.0750.060–0.1000.075–0.1250.090–0.1500.120–0.2000.150–0.2500.180–0.3000.240–0.4000.300–0.5000.375–0.625
BronzeC932 bearing bronze, phosphor bronzeN0.020–0.0400.030–0.0600.040–0.0800.050–0.1000.060–0.1200.080–0.1600.100–0.2000.120–0.2400.160–0.3200.200–0.4000.250–0.500
CopperC110, C101 (pure copper)N0.020–0.0400.030–0.0600.040–0.0800.050–0.1000.060–0.1200.080–0.1600.100–0.2000.120–0.2400.160–0.3200.200–0.4000.250–0.500
PlasticsAcetal (POM, Delrin), nylon (PA)N0.030–0.0500.045–0.0750.060–0.1000.075–0.1250.090–0.1500.120–0.2000.150–0.2500.180–0.3000.240–0.4000.300–0.5000.375–0.625
Titanium alloyTi-6Al-4V (Grade 5)S0.014–0.0280.021–0.0420.028–0.0560.035–0.0700.042–0.0840.056–0.1120.070–0.1400.084–0.1680.112–0.2240.140–0.2800.175–0.350
Nickel alloyInconel 718S0.010–0.0200.015–0.0300.020–0.0400.025–0.0500.030–0.0600.040–0.0800.050–0.1000.060–0.1200.080–0.1600.100–0.2000.125–0.250
Hardened steelThrough-hardened tool and alloy steelH0.010–0.0200.015–0.0300.020–0.0400.025–0.0500.030–0.0600.040–0.0800.050–0.1000.060–0.1200.080–0.1600.100–0.2000.125–0.250

Millimetres per revolution. Drill diameters in millimetres.

Turning feed per revolution

Starting feed for a general-purpose turning insert or HSS tool bit with about a 1/32 in (0.8 mm) nose radius. Roughing assumes a depth of cut of roughly 0.040–0.150 in (1–4 mm); finishing feed is limited by the nose radius and the surface finish you need (see the Surface Finish Predictor).

MaterialISORoughingin/revmm/revFinishingin/revmm/rev
Low-carbon steel1018, 1020, EN3 / S235P0.010–0.0200.25–0.510.004–0.0080.10–0.20
Medium-carbon steel1045, EN8 / C45P0.010–0.0200.25–0.510.004–0.0080.10–0.20
Alloy steel, annealed4140, 42CrMo4 / EN19P0.010–0.0200.25–0.510.004–0.0080.10–0.20
Tool steel, annealedO1, A2, D2, H13P0.010–0.0200.25–0.510.004–0.0080.10–0.20
Alloy steel, pre-hardened4140 HT, 4140 PH, EN19TP0.008–0.0150.20–0.380.004–0.0080.10–0.20
Stainless steel, free-machining303, 416M0.010–0.0200.25–0.510.004–0.0080.10–0.20
Stainless steel, austenitic304, 316, 316LM0.008–0.0150.20–0.380.004–0.0080.10–0.20
Grey cast ironClass 30–40, GG25 / EN-GJL-250K0.010–0.0200.25–0.510.004–0.0080.10–0.20
Aluminium, wrought6061-T6, 6082-T6, 7075-T6, 2024N0.010–0.0200.25–0.510.003–0.0080.08–0.20
Aluminium, cast / high-siliconA356, A380, LM25, A390N0.010–0.0200.25–0.510.003–0.0080.08–0.20
Brass, free-cuttingC360, CZ121N0.010–0.0200.25–0.510.003–0.0080.08–0.20
BronzeC932 bearing bronze, phosphor bronzeN0.008–0.0150.20–0.380.003–0.0060.08–0.15
CopperC110, C101 (pure copper)N0.008–0.0150.20–0.380.003–0.0060.08–0.15
PlasticsAcetal (POM, Delrin), nylon (PA)N0.010–0.0200.25–0.510.003–0.0080.08–0.20
Titanium alloyTi-6Al-4V (Grade 5)S0.006–0.0120.15–0.300.003–0.0060.08–0.15
Nickel alloyInconel 718S0.005–0.0100.13–0.250.003–0.0060.08–0.15
Hardened steelThrough-hardened tool and alloy steelH0.003–0.0060.08–0.150.002–0.0040.05–0.10

With HSS tool bits, start at the low end of each range.

RPM and feed formulas

RPM = SFM × 12 ÷ (π × D)  ≈  SFM × 3.82 ÷ D   (D in inches)
RPM = Vc × 1000 ÷ (π × D)   (Vc in m/min, D in mm)
Milling feed = RPM × chip load × number of flutes   (IPM or mm/min)
Drilling and turning feed = RPM × feed per rev   (IPM or mm/min)

For turning, D is the workpiece diameter being cut, so the RPM rises as the diameter falls. On a CNC lathe use constant surface speed (G96) with a spindle limit (G50 or G92) and program the feed per rev (G95 or G99, depending on the control).

Worked examples

Inch: 1/2 in carbide end mill in 1018 steel

  • Surface speed: the chart gives 250–450 SFM, so start at the middle, 350 SFM.
  • RPM = 350 × 12 ÷ (π × 0.5) = 2,674 RPM.
  • Chip load: 0.0020–0.0035 in at 1/2 in, middle about 0.0028 in per tooth.
  • Feed = 2,674 × 0.0028 × 4 flutes = 29.9 IPM.

Metric: 12 mm carbide end mill in 1018 steel

  • Surface speed: 75–135 m/min, middle 105 m/min.
  • RPM = 105 × 1000 ÷ (π × 12) = 2,785 RPM.
  • Chip load: 0.048–0.085 mm at 12 mm, middle about 0.067 mm per tooth.
  • Feed = 2,785 × 0.067 × 4 flutes = 746 mm/min.

When the machine runs out of RPM

A 1/8 in 3-flute carbide end mill in 6061 at 1,050 SFM wants 32,086 RPM. On a 10,000 RPM spindle, run at 10,000 RPM (now only 327 SFM) and keep the chip load at 0.0015 in: feed = 10,000 × 0.0015 × 3 = 45 IPM. Do not raise the chip load to make up for the lost speed.

ISO material groups

Tool makers sort workpiece materials into six groups defined in ISO 513, each with a colour. Pick inserts, grades and cutting data from the group your material belongs to.

GroupColourMaterials
PBlueCarbon, alloy and tool steels (not hardened), ferritic and martensitic stainless
MYellowAustenitic and duplex stainless steels (303, 304, 316)
KRedGrey, ductile and malleable cast iron
NGreenAluminium, copper, brass, bronze, plastics and other non-ferrous materials
SOrangeHeat-resistant superalloys (Inconel and other nickel and cobalt alloys) and titanium
HGreyHardened steel (about 45–65 HRC), chilled cast iron

Groups per ISO 513. 416 stainless is a martensitic grade (ISO P in most catalogues) but is listed here with 303 because the cutting data is similar.

Adjusting from the starting point

  • Start in the middle, then move. Run a test cut at the middle of the range. If the tool is quiet, the chips are well formed and the tool is not getting hot, go up; if it chatters, smokes or wears quickly, come down.
  • Speed burns tools; feed breaks them. Too much SFM shows as worn, glowing or discoloured edges. Too much chip load shows as chipped edges or snapped tools.
  • Too little feed is also a problem. Rubbing work-hardens stainless and nickel alloys and dulls the tool. Keep the chip load at least at the low end of the range.
  • Read the chips. In steel, straw to light blue chips with carbide are normal; dark blue or purple chips mean too much speed. Aluminium chips should be clean and shiny, not welded to the flutes.
  • Long tools and weak set-ups. For stick-out over about 3× diameter, reduce speed and feed by 20–50%, or use the Cutting Force Calculator to check the load.
  • Full slotting. Use the low end of the chip load and keep the axial depth to about 0.5–1× diameter. Ramp or helix into pockets instead of plunging straight in with an end mill.
  • Check the hardness. “4140” can be 200 HB or 32 HRC. Test it or check the certificate, and convert readings with the Hardness Converter.

Frequently asked questions

For a carbide end mill in wrought aluminium such as 6061-T6, start at 600 to 1,500 SFM (185 to 455 m/min). HSS end mills start at 250 to 500 SFM. Small machines often reach their maximum RPM first; then keep the chip load and accept the lower surface speed.

RPM = SFM × 12 ÷ (π × D), with D the tool diameter in inches; 12 ÷ π is about 3.82. In metric, RPM = Vc × 1000 ÷ (π × D), with Vc in m/min and D in mm. For example, 350 SFM with a 1/2 in end mill gives 2,674 RPM.

For a 1/2 in carbide end mill in 1018 or 1045 steel, start at 0.0020 to 0.0035 in per tooth. In 304 stainless or pre-hardened 4140 start at 0.0015 to 0.0028 in, and in aluminium at 0.0035 to 0.0060 in. Use less for long reach or deep slots, and more for light radial cuts because of chip thinning.

In this chart carbide starts at roughly 2 to 4 times the HSS surface speed for the same material: about 2 to 3 times in aluminium, brass and plastics, and about 3 to 4 times in steel, stainless and cast iron. Our shop drill chart runs carbide drills about 4.4 times faster than HSS in mild steel (145 vs 33 m/min) and 4.2 times in stainless (55 vs 13 m/min). The chip load per tooth stays about the same, but start HSS tools at the low end.

They are conservative starting points meant to work with typical coated carbide and HSS tools on an average machine. Premium tools, high-pressure coolant, a rigid machine and light radial engagement can run much faster. Start here, then work up toward the maker's figures while watching the chips, the sound and the tool wear.

Sources: starting ranges rounded conservatively from Machinery's Handbook (Industrial Press) speed and feed tables and published starting data from carbide tool makers (Sandvik Coromant, Kennametal, Harvey Tool, Helical Solutions); ISO 513 for the material groups. These are typical values for general guidance, not guaranteed figures. Always check critical work against your tool manufacturer's recommendations for the exact tool, grade and coating.