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Metal Punching
|
Mild Steel Punching Pressure (in tons) |
|||||||||||||
| 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 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 |
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