Ideambox
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TOOL IDB-MEC-005
Thread engagement

Desktop only

Engineering tools are available only on desktop screens.

Thread engagement

Minimum engagement so female threads can react the bolt's full preload without stripping. From the shear-strength ratio.

Bolt into parent material — ×D
Parent Le = — D = 4 mm
Engineering notes

Rule

  • Engagement ratio ≈ (UTSbolt · As) / (UTSparent · An), adjusted for shear.
  • Simpler: Le = D · (UTSbolt / UTSparent) · 0.65

Defaults

  • Steel into steel: 1.0×D
  • Steel into aluminium: 1.5–2.0×D
  • Steel into zinc die-cast: 2.0–2.5×D
  • Plastic boss: 2.0–2.5×D + heat-set insert.

Result

Live