Thread Engagement Length
Verify thread-flank shear and bearing stress at engagement length L and compute required minimum length (ISO 261 / GB metric threads).
Inputs
Formula
τ = F/(0.5πdL); σc = F/(0.75πdL); L_req = F/(0.5πd·[τ])
How to use
- Fill in Axial force F, Major dia. d, Engagement L, Allow. shear [τ], Allow. bearing [σc] in the Inputs section (watch the unit on each field).
- Click Calculate; the tool evaluates the formula shown above.
- Read Actual shear τ, Bearing stress σc, Required length L_req in the results area.
Formula notesThread engagement Le sets joint strength; typically Le ≥ 0.8 d (steel–cast iron) or ≥ 1.0 d (steel–aluminium).