Free engineering tool
Thread Engagement Length
Minimum engaged length so the internal thread strips at or above the bolt fracture — for blind/tapped holes and softer materials.
How this is calculated
Bolt tensile capacity = stress area × Rm (from property class). The internal thread strips in shear at ~0.58×Rm over an engaged area ≈ 0.55·π·d per mm. The engagement length is set so the internal thread is at least as strong as the bolt — so the bolt fails first, not the threads. Reference estimate; confirm critical joints against the drawing.
Bolt tensile capacity
60.31 kN
Minimum engagement length
13.4 mm
Engagement ÷ diameter
1.34× d
Needs more than a standard nut — use a thicker nut or deeper tapped engagement.
Reference estimate — not a joint specification
- •A softer tapped material (aluminium, cast iron) needs a longer engagement than a steel nut.
- •Property class comes from material + heat treatment — harden to the class first, then this engagement applies.
- •Confirm critical or fatigue-loaded joints against the drawing and the fastener standard.