Round
Hole
Diameter |
Ga. |
20 |
18 |
16 |
14 |
12 |
11 |
10 |
3/16" |
1/4" |
5/16" |
3/8" |
1/2" |
| In. |
.036 |
.048 |
.062 |
.075 |
.105 |
.120 |
.135 |
.188 |
.250 |
.312 |
.375 |
.500 |
| 1/8" |
|
.4 |
.5 |
.6 |
.7 |
1.0 |
1.2 |
1.3 |
- |
- |
- |
- |
- |
| 3/16" |
|
.5 |
.7 |
.9 |
1.1 |
1.5 |
1.8 |
2.0 |
2.8 |
- |
- |
- |
- |
| 1/4" |
|
.7 |
.9 |
1.2 |
1.5 |
2.1 |
2.4 |
2.6 |
3.7 |
4.9 |
- |
- |
- |
| 5/16" |
|
.9 |
1.2 |
1.5 |
1.8 |
2.6 |
2.9 |
3.3 |
4.6 |
6.1 |
7.8 |
- |
- |
| 3/8" |
|
1.1 |
1.4 |
1.8 |
2.2 |
3.1 |
3.5 |
4.0 |
5.5 |
7.4 |
9.2 |
11.1 |
- |
| 7/16" |
|
1.2 |
1.6 |
2.1 |
2.6 |
3.6 |
4.1 |
4.6 |
6.4 |
8.6 |
10.7 |
12.8 |
- |
| 1/2" |
|
1.4 |
1.9 |
2.3 |
2.9 |
4.1 |
4.7 |
5.3 |
7.4 |
9.8 |
12.3 |
14.8 |
19.7 |
| 9/16" |
|
1.6 |
2.1 |
2.6 |
3.3 |
4.6 |
5.1 |
5.9 |
8.3 |
11.1 |
13.9 |
16.5 |
22.0 |
| 5/8" |
|
1.8 |
2.4 |
2.9 |
3.7 |
5.1 |
5.9 |
6.6 |
9.2 |
12.3 |
15.4 |
18.5 |
24.6 |
| 11/16" |
|
1.9 |
2.6 |
3.2 |
4.0 |
5.7 |
6.2 |
7.3 |
10.1 |
13.5 |
17.0 |
20.2 |
26.9 |
| 3/4" |
|
2.1 |
2.8 |
3.5 |
4.4 |
6.2 |
7.1 |
7.9 |
11.0 |
14.7 |
18.5 |
22.1 |
29.5 |
| 13/16" |
|
2.3 |
3.1 |
3.8 |
4.8 |
6.7 |
7.6 |
8.6 |
12.0 |
16.0 |
20.0 |
23.8 |
31.8 |
| 7/8" |
|
2.5 |
3.3 |
4.1 |
5.1 |
7.2 |
8.3 |
9.2 |
12.9 |
17.2 |
21.5 |
25.8 |
34.4 |
| 15/16" |
|
2.6 |
3.5 |
4.4 |
5.5 |
7.7 |
8.8 |
9.9 |
13.8 |
18.4 |
23.0 |
27.5 |
36.8 |
| 1" |
|
2.8 |
3.8 |
4.7 |
5.9 |
8.2 |
9.4 |
10.6 |
14.8 |
19.7 |
24.6 |
29.5 |
39.4 |
| 1
1/2" |
|
4.2 |
5.5 |
7.0 |
8.8 |
12.3 |
14.0 |
25.9 |
22.0 |
34.4 |
43.0 |
51.5 |
68.8 |
| 2" |
|
5.6 |
7.5 |
9.5 |
11.7 |
16.4 |
18.8 |
21.0 |
29.5 |
39.3 |
49.0 |
59.0 |
78.5 |
| 2
1/2" |
|
7.0 |
9.4 |
11.7 |
14.7 |
20.5 |
23.5 |
26.5 |
36.8 |
49.0 |
61.5 |
73.6 |
98.2 |
| 3" |
|
8.5 |
11.3 |
14.0 |
17.6 |
24.5 |
28.2 |
31.7 |
44.2 |
60.0 |
76.5 |
88.4 |
118.0 |
| 3
1/2" |
|
9.9 |
13.0 |
16.5 |
20.5 |
28.8 |
32.7 |
37.0 |
51.5 |
68.7 |
86.0 |
103.0 |
137.0 |
| 4" |
|
11.3 |
15.0 |
18.8 |
23.5 |
32.8 |
37.6 |
42.2 |
60.0 |
78.5 |
98.0 |
188.0 |
157.0 |
Die Clearance
The relationship of the larger die
hole size to the punch size is die clearance and is stated as
a percentage of the thickness of the material being punched. The
range of clearances varies from 10% for thin materials to 20%
for thicker materials. For 3/4" material the total die clearance
is .150". Clearance should always be specified when there is any
reason for doubt.
Die Clearance has the following
effects:
Too much clearance
- Extra roll-in at top of the hole.
- Too much burr at the bottom of
the hole.
Too little clearance
- More punching pressure is needed.
Can reduce tool life.
- High stripping force causes part
distortion and extra punch wear.
Correct clearance
- Straighter hole thru material.
- Minimum distortion at top of hole.
- Minimum burr at bottom of hole.
Effects of die clearance are more
noticeable in thicker materials (such as 1/4:) than in thinner
materials (such as 16 gauge).
Clearances For
Mild Steel
| Gauge or Size |
Approx. Decimal Thickness |
Overall Clearance -
Add To Punch Size |
| 30 |
.0120 |
Slip
Fit |
| 28 |
.0149 |
Slip
Fit |
| 26 |
.0179 |
|
| 24 |
.0239 |
.003 |
| 22 |
.0299 |
.003 |
| 20 |
.0359 |
.004 |
| 18 |
.0478 |
.005 |
| 16 |
.0598 |
.005 |
| 14 |
.0747 |
.006 |
| 13 |
.0897 |
.009 |
| 12 |
.1046 |
.009 |
| 11 |
.1196 |
.011 |
| 1/8 |
.125 |
.011 |
| 10 |
.1345 |
.013 |
| 5/32 |
.156 |
.015 |
| 8 |
.164 |
.017 |
| 7 |
.1793 |
.021 |
| 3/16 |
.1875 |
.023 |
| 1/4 |
.250 |
.037 |
| 5/16 |
.3125 |
.047 |
| 3/8 |
.375 |
.057 |
| 1/2 |
.500 |
.075 |
| 5/8 |
.625 |
.125 |
| 3/4 |
.750 |
.150 |
