3.2.2 FASTENING TO STEEL
3.2.2.1 GENERAL SUITABILITY
When a powder , battery , or gas-actuated fastener is driven into steel , the steel around the fastener shank is displaced . This displaced steel flows back around the shank and into the knurling creating a keying hold or , in the case of smooth shank fasteners , a friction hold . In addition , the local heat generated during the driving process causes partial fusion of the fastener to the steel .
A fastener driven into steel is influenced by the following factors :
• Base steel thickness
• Tensile strength of base steel
• Fastener spacing and edge distance
• Fastener shank diameter
• Fastener shank knurling
Direct Fastening Technical Guide , Edition 24
3.2.2.2 FASTENER SPACING , EDGE DISTANCE AND BASE MATERIAL THICKNESS REQUIREMENTS FOR STEEL
C min
= Min . Edge Distance = 1 / 2 " ( 12 mm ) 1
S min
= Min . Fastener Spacing without reduction in performance = 1 " ( 25 mm ) 1 t II
= Min . Base Steel Thickness = 1 / 8 " ( 3 mm ) 2
1 Unless otherwise noted ( e . g . X-BT-MR and X-BT-GR fastener ) 2 Some fasteners require thicker base steel ( e . g . X-EW10H , X-BT-MR and X-BT-GR )
S min
C min t II
3.2.2.3 BASE STEEL THICKNESS AND FASTENER DRIVING DISTANCE REQUIREMENTS
Holding power |
Optimum thickness 3 / 8 " to 1 / 2 " ( 10 to 12 mm ) |
base steel thickness |
Application range for standard knurled fasteners |
Steel thickness
Optimal holding power is obtained when fastener point is driven to distance h ET
.
Base steel tensile strength ( x1000 ) psi
As the tensile strength of the base steel increases , the thickness of the base steel suitable for DX / GX fastenings decreases .
Fastener type
Recommended driving distance to achieve optimal tension capacity , h ET
* in . mm
L S |
L S
= h ET + t I
|
t I
h ET
|
L S |
h ET |
X-U |
0.394 - 0.551 |
10 - 14 |
X-U 15 |
0.433 - 0.551 |
11 - 14 |
X-EW6H-xx-9 |
0.315 - 0.433 |
8 - 11 |
EDS |
0.472 - 0.669 |
12 - 17 |
X-S 14 B3 , G3 |
0.315 - 0.433 |
8 -11 |
X-P B3 , G3 |
0.315 - 0.630 |
8-16 |
X-EW10H-xx-14 |
0.512 - 0.630 |
13 - 16 |
DS |
0.669 - 1.063 |
17 - 27 |
X-S13 P8THP |
0.394 - 0.472 |
10 -12 |
X-S16 P8TH |
> 0.433 |
> 11 |
X-R |
> 0.394 |
> 10 |
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* The objective of this table is to ensure adequate through-penetration of the base steel . For load capacity of fasteners without through-penetration , refer to corresponding allowable load tables and applicable footnotes for more details . AISI S100 , Section J5 , provides additional information regarding point penetration of PAF ’ s in steel . |
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