Why Keyways & Splines Cause Shaft Failure

Mechanical Engineering Made Simple · Jun 25, 2026 · 18m

Discover Why Keyways and Splines Cause Shaft Failure — the hidden stress concentrators that turn strong rotating shafts into the most common failure points in mechanical engineering. We break down how keyways and splines create sharp geometric discontinuities that multiply local stresses (often 2–4x or higher), act as fatigue crack initiation sites, reduce torsional strength, cause fretting corrosion, and lead to sudden brittle fractures or progressive fatigue cracks under cyclic loading — even when average shaft stress looks safe.

Discover The Gearbox Killer — why heavily engineered shafts…