Self Tapping Screws Torque Data
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These tables show the minimum torsional load, plate thickness and hole diameter for metric and imperial self tapping screws.
For guidance only
| Types AB,B,BT & Y | |||
| Screw Size | Minimum Torsional Load | ||
| mm | No. | Nm | lbf in |
| 2.2 | 2 | 0.49 | 4 |
| 2.9 | 4 | 1.47 | 13 |
| 3.5 | 6 | 2.74 | 24 |
| 4.2 | 8 | 4.41 | 39 |
| 4.8 | 10 | 6.27 | 56 |
| 5.5 | 12 | 10.78 | 88 |
| 6.3 | 14 | 15.98 | 142 |
| 7 | 16 | 34.71 | 290 |
| Application Test Plates for Types AB,B,BT & Y | |||||
| Screw Size | Plate Thickness | Hole Diameter | |||
| mm | No. | mm | in. | mm | in. |
| 2.2 | 2 | 1.22 | 0.048 | 1.93 | 0.076 |
| 2.9 | 4 | 1.22 | 0.048 | 2.44 | 0.096 |
| 3.5 | 6 | 2.03 | 0.08 | 2.95 | 0.116 |
| 4.2 | 8 | 2.03 | 0.08 | 3.46 | 0.136 |
| 4.8 | 10 | 3.18 | 0.125 | 4.05 | 0.159 |
| 5.5 | 12 | 3.18 | 0.125 | 4.75 | 0.188 |
| 6.3 | 14 | 4.75 | 0.187 | 5.5 | 0.217 |
| 7 | 16 | 4.75 | 0.187 | 6.91 | 0.272 |
| Unified Threads Types D & T | ||
| Screw Size | Minimum Torsional Load | |
| No. | Threads per Inch | lbf in |
| 4 | 40 | 13 |
| 4 | 48 | 15 |
| 6 | 32 | 23 |
| 6 | 40 | 27 |
| 8 | 32 | 42 |
| 8 | 36 | 47 |
| 10 | 24 | 56 |
| 10 | 32 | 74 |
| 1/4" | 20 | 140 |
| 1/4" | 28 | 179 |
| 5/16" | 18 | 306 |
| 5/16" | 24 | 370 |
| Application Test Plates for Types D & T | |||||
| Screw Size | Plate Thickness | Hole Diameter | |||
| No. | Threads per Inch | mm | in. | mm | in. |
| 4 | 40 | 2.77 | 0.109 | 2.4 | 0.096 |
| 4 | 48 | 2.77 | 0.109 | 2.44 | 0.096 |
| 6 | 32 | 3.58 | 0.141 | 3.05 | 0.12 |
| 6 | 40 | 3.58 | 0.141 | 3.05 | 0.12 |
| 8 | 32 | 3.58 | 0.141 | 3.74 | 0.147 |
| 8 | 36 | 3.58 | 0.141 | 3.74 | 0.147 |
| 10 | 24 | 4.75 | 0.187 | 4.4 | 0.173 |
| 10 | 32 | 4.75 | 0.187 | 4.5 | 0.177 |
| 1/4" | 20 | 6.35 | 0.25 | 5.79 | 0.228 |
| 1/4" | 28 | 6.35 | 0.25 | 5.94 | 0.234 |
| 5/16" | 18 | 7.92 | 0.312 | 7.36 | 0.29 |
| 5/16" | 24 | 7.92 | 0.312 | 7.5 | 0.295 |
The minimum torsional loads shown for unified sizes are based on BS 1580, an imperial units standard.