Machinability Ratings

Machinability Ratings of Materials

What is Machinability?

Machinability of a material can be defined as the ease with which it can be machined.

The American Iron and Steel Institute (AISI) determined the machinability ratings for a wide variety of materials. They determined this by running turning tests at 180 surface ft/min (sfpm). The AISI then arbitrarily assigned 160 Brinell B-1112 steel a machinability rating of 100%. The machinability rating is determined by measuring the weighed averages of the normal cutting speed, surface finish, and tool life for each material.

Machinability Ratings

Note that a material with a machinability rating less than 100% would be more difficult to machine than B-1112 and material with a value more than 100% would be easier.

STAINLESS STEELS
Grade Approx. Surf. ft/min % Relative Speed Based on B-1112 as 100%
302 70 40
302/304 B 55 28
303 150 75
303 High Tensile 80 43
304 70 40
304L 70 40
309 60 36
310 60 36
316 60 36
316 B 50 22
316 L 60 36
317 – 317 L 60 36
321 60 36
330 45 20
347 60 36
410 95 54
416 Ann 150 75
416 H.T. 85 50
418 (Greek Ascoloy) 96 50
420 85 50
420 F 125 68
430 110 66
430 F 150 75
431 80 48
440 A 65 40
440 C 65 40
440 F Se 80 48
446 60 36
PH-13-8-MO 60 36
15-5 PH 75 45
17-4 PH 75 45
17-4 PH H1150 85 50
17-7 PH 75 45
AM 355 72 42
Nitonic 40 (21-6-9) 50 22
Nitronic 50 (22-13-5) 50 22
Nitronic 60 (22-4-9 50 22
Carp. 20 70 40
SUPER ALLOYS – ELECTRICAL STEELS
Grade Approx. Surf. ft/min % Relative Speed Based on B-1112 as 100%
Maraging 300 60 36
A-286 (Discalloy) 54 28
4750 60 36
L-605 15 9
Nickel 200 110 66
Monel 400 80 48
Monel 405 80 48
Monel K500 60 36
Inconel 600 50 22
Inconel 625 20 12
Inconel 718 20 12
Inconel X-750 20 12
Invar 35 FM 92 55
Waspalloy 45 20
Hastelloy C (C-276) 40 18
Hastelloy X 45 20
Kovar 60 22
Rene 41 15 9
ALLOY
Grade Approx. Surf. ft/min % Relative Speed Based on B-1112 as 100%
E-4130 120 72
E-4130 H.T. 65 40
E-4140 110 66
E-4330 Mod. 95 57
E-4340 95 57
Mod 300 M 95 57
E-4620 110 66
E-52100 65 65
E-6150 100 60
E-8740 110 66
E-9310 80 49
Nitriding 83 51
H-11 75 45
Hy-Tuf 75 45
D6AC 80 49
CARBON
Grade Approx. Surf. ft/min % Relative Speed Based on B-1112 as 100%
C-1018 130 78
C-1045 95 57
C-1117 150 91
C-1137 120 72
C-1144 125 76
C-12L14 325 198
C-1215 225 136
Ledloy (A) 325 198
Stressproof 125 76

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