PUNCHING INFORMATION
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PUNCHING INFORMATION |
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Please feel free to highlight any of the tables or information and print it for quick reference in your shop or at your equipment.
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Tons of Pressure Required to Punch Mild Steel ( tonnage based on flat punches, taper punches require less because of their progressive shearing action ) |
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| Mittler Brothers Machine & Tool | |||||||||||||
| 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 | |
| Punch to Die Clearances For Mild Steel | ||
| Mittler Brothers Machine & Tool | ||
| Gauge or Thickness | Decimal Thickness | Overall
Clearance To Add To Punch Size |
| 30 | .0120 | Slip Fit |
| 28 | .0149 | Slip Fit |
| 26 | .0179 | .002 |
| 24 | .0239 | .003 |
| 22 | .0299 | .003 |
| 20 | .0359 | .004 |
| 18 | .0478 | .005 |
| 16 | .0598 | .006 |
| 14 | .0747 | .007 |
| 13 | .0897 | .009 |
| 12 | .1046 | .010 |
| 11 | .1196 | .012 |
| 1/8 | .125 | .012 |
| 10 | .1345 | .013 |
| 9 | .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 |
Punch to Die Clearance
The relationship of the larger die hole size to the punch size is called die clearance. This is based on 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.
Too much clearance will result in:
Extra roll-in at top of the hole.
Too much burr at the bottom of the hole.
Too little clearance will result in:
More punching pressure is needed. Can reduce tool life.
High stripping force causes part distortion and extra punch wear.
Correct clearance will result in:
Straighter hole thru material.
Minimum distortion at top of hole.
Minimum burr at bottom of hole.
The thicker the material the more noticeable are the effects of die clearance: say 1/4" compared to 1/16".
Copyright 2003 - 2008. Mittler Brothers Machine and Tool. All Rights Reserved. If you have questions or comments, e-mail
Revised: December 31, 2007
