Table 11. Cutting Speeds and Feeds for Milling Plain Carbon and Alloy Steels Table 11. (Continued) Cutting Speeds and Feeds for Milling Plain Carbon and Alloy Steels
End Milling
Face Milling
Slit Milling
HSS
HSS
Uncoated Carbide Coated Carbide Uncoated Carbide Coated Carbide Uncoated Carbide Coated Carbide
Brinell Hardness Number a 220-300 300-350 350-400
f = feed (0.001 in/tooth), s = speed (ft/min) Metric Units: f 3 25.4 = mm/rev, s 3 0.3048 = m/min
Speed (fpm)
Material
Opt. Avg. Opt.
Avg. Opt.
Avg. Opt.
Avg. Opt.
Avg. Opt.
Avg. Opt.
Avg.
60 45 20
f s f s f s f s f s f s f s
8 165 8 150 5 20 † 8 165 5 20 † 15 105
4 355 4 320
8 300
4 480
Ultra-high-strength steels (not AISI): AMS 6421 (98B37 Mod.), 6422 (98BV40), 6424, 6427, 6428, 6430, 6432, 6433, 6434, 6436, and 6442; 300M, D6ac
8 15
4 45
39 130
20 235
39 75 39 5
20 175
3 55
20 15
43-52 RC —
4 355
8 300
4 480
250-325
50
Maraging steels (not AISI): 18% Ni Grades 200, 250, 300, and 350
3 55
39 5
20 15
50-52 RC —
15 7 15 5
8 30 8 20
8 270 8 155
15 220
8 450 8 225
39 295 39 175
20 475
39 135
20 305
39 265
20 495
200-250
60
Nitriding steels (not AISI): Nitralloy 125, 135, 135 Mod., 225, and 230, Nitralloy N, Nitralloy EZ, Nitrex 1
15 40
15 75
20 280
300-350
25
a Brinell Hardness Number given unless otherwise indicated by RC for hardness on the Rockwell C scale. For HSS (high-speed steel) tools in the first speed column only, use Table 15a for recommended feed in inches per tooth and depth of cut. End Milling: Table data for end milling are based on a 3-tooth, 20-degree helix angle tool with a diameter of 1.0 inch, an axial depth of cut of 0.2 inch, and a radial depth of cut of 1 inch (full slot). Use Table 15b to adjust speeds for other feeds and axial depths of cut, and Table 15c to adjust speeds if the radial depth of cut is less than the tool diameter. Speeds are valid for all tool diameters. Face Milling: Table data for face milling are based on a 10-tooth, 8-inch diameter face mill, operating with a 15-degree lead angle, 3 ∕ 64 -inch nose radius, axial depth of cut = 0.1 inch, and radial depth (width) of cut = 6 inches (i.e., width of cut to cutter diameter ratio = 3 ∕ 4 ). These speeds are valid if the cutter axis is above or close to the center line of the workpiece (eccentricity is small). Under these conditions, use Table 15d to adjust speeds for other feeds and axial and radial depths of cut. For larger eccentricity (i.e., when the cutter axis to workpiece center line offset is one half the cutter diameter or more), use the end and side milling adjustment factors (Table 15b and Table 15c) instead of the face milling factors. Slit and Slot Milling: Table data for slit milling are based on an 8-tooth, 10-degree helix angle tool with a cutter width of 0.4 inch, diameter D of 4.0 inches, and a depth of cut of 0.6 inch. Speeds are valid for all tool diameters and widths. See the examples in the text for adjustments to the given speeds for other feeds and depths of cut. Tool life for all tabulated values is approximately 45 minutes; use Table 15e to adjust tool life from 15 to 180 minutes. The combined feed/speed data in this table are based on tool grades (identified in Table 16) as follows: end and slit milling uncoated carbide = 20 except † = 15; face milling uncoated carbide = 19; end, face, and slit milling coated carbide = 10.
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