Page 1052 - Tungaloy Catalog

Technical Reference
International Tolerance (IT Grades)
International Tolerance (IT Grades)

IT grades shows a tolerance allowable for difference of the diameters of a hole and a shaft. As the number added after IT
increases, the tolerance becomes rough. Depending on the basic size, the tolerance value in each grade varies.
In the catalog, IT grades are shown as a guide of dimensional dispersion in the diameters of holes machined with the drill. H8
tolerance for a ø8.0 hole is 0 to + 0.022 mm, the width of the value is the same as that of IT 8.
In the Table shown below, tolerance areas attainable with typical drilling tools are distinguished by using different colors.
Solid drills are generally used for machining holes of IT 9 to 12. For machining a hole greater than IT 8, finishing process such
as reaming is required. For a hole greater than IT 5, high-precision finishing is required. Above description is based on machining
general steel. The IT grade attained with the tool varies widely depending on the hardness and the composition of the work material.

d IT (International Tolerance) Grades
Basic sizes International Tolerance Grades
(in) IT1 IT2 IT3 IT4 IT5 IT6 IT7 IT8 IT9 IT10 IT11 IT12 IT13 IT14 IT15 IT16 IT17 IT18
> ≤ (μm) (mm)
- 3 0.8 1.2 2 3 4 6 10 14 25 40 60 0.1 0.14 0.25 .016 0.6 1 1.4
3 6 1 1.5 2.5 4 5 8 12 18 30 48 75 0.12 0.18 0.3 0.48 0.75 1.2 1.8
6 10 1 1.5 2.5 4 6 9 15 22 36 58 90 0.15 0.22 0.36 0.58 0.9 1.5 2.2
10 18 1.2 2 3 5 8 11 18 27 43 70 110 0.18 0.27 0.43 0.7 1.1 1.8 2.7
18 30 1.5 2.5 4 6 9 13 21 33 52 84 130 0.21 0.33 0.52 0.84 1.3 2.1 3.3
30 50 1.5 2.5 4 7 11 16 25 39 62 100 160 0.25 0.39 0.62 1 1.6 2.5 3.9
50 80 2 3 5 8 13 19 30 46 74 120 190 0.3 0.46 0.74 1.2 1.9 3 4.6
80 120 2.5 4 6 10 15 22 35 54 87 140 220 0.35 0.54 0.87 1.4 2.2 3.5 5.4
120 180 3.5 5 8 12 18 25 40 63 100 160 250 .016 0.63 1 1.6 2.5 4 6.3
180 250 4.5 7 10 14 20 29 46 72 115 185 290 0.46 0.72 1.15 1.85 2.9 4.6 7.2
250 315 6 8 12 16 23 32 52 81 130 210 320 0.52 0.81 1.3 2.1 3.2 5.2 8.1
315 400 7 9 13 18 25 36 57 89 140 230 360 0.57 0.89 1.4 2.3 3.6 5.7 8.9
400 500 8 10 15 20 27 40 63 97 155 250 400 0.63 0.97 1.55 2.5 4 6.3 9.7
500 630 9 11 16 22 32 44 70 110 175 280 440 0.7 1.1 1.75 2.8 4.4 7 11
630 800 10 13 18 25 36 50 80 125 200 320 500 0.8 1.25 2 3.2 5 8 12.5
800 1000 11 15 21 28 40 56 90 140 230 360 560 0.9 1.4 2.3 3.6 5.6 9 14
1000 1250 13 18 24 33 47 66 105 165 260 420 660 1.05 1.65 2.6 4.2 6.6 10.5 16.5
1250 1600 15 21 29 39 55 73 125 195 310 500 780 1.25 1.95 3.1 5 7.8 12.5 19.5
92
1600 2000 18 25 35 46 65 110 150 230 370 600 920 1.5 2.3 3.7 6 9.2 15 23
Technical Reference 2500 3150 26 36 50 68 Tolerance area 330 Tolerance area 2.1 Tolerance area 21 33
175
7
78
280
4.4
2.8
440
700 1100 1.75
2500
22
30
2000
28
11 17.5
55
41
860 1350
3.3
8.6 13.5
540
135
210
96
5.4
requiring finishing
process such as
solid drill.
indexable drill.
with a reamer. attainable with a attainable with an
14
14–34