- ISO 6336
- AGMA 2001-D04
- Engineering depth
Gear engineering,
written at the
level it demands.
Technical articles on cylindrical gear design, strength rating,
and failure analysis — derived from ISO 6336:2019 and written
by a mechanical designer and quality inspector who uses these
calculations in production.
No shortcuts in the math · No assumptions left unnamed · No standard misquoted
07/07/2026
31 min read
ISO 6336 Tooth Bending Strength: The Complete $S_F$ Calculation Walkthrough
A complete derivation of the ISO 6336-3:2019 tooth bending safety factor $S_F$ — including $Y_F$ from tooth root geometry, $Y_S$ stress correction, $Y_ST$ = 2.0 and why it exists, $Y_B$ rim thickness, $Y_DT$ double tip loading, and the five errors that corrupt bending calculations in practice. Method B, external cylindrical gears.
07/07/2026
25 min read
ISO 6336 Pitting Resistance: The Complete $S_H$ Calculation Walkthrough
A complete, factor-by-factor derivation of the ISO 6336-2:2019 contact safety factor $S_H$ — including $Z_B$/$Z_D$, $Z_NT$ for long life, the $Z_W$ asymmetry, and the three calculation errors that appear in practice. Method B, external cylindrical gears.