Engineering
The Mechanics of Snap-Fit Joints in Consumer Plastic Enclosures
Quick fact
A well-designed snap-fit hook can endure tens of thousands of assembly cycles, and its holding force is determined by the stiffness of the cantilever beam and the coefficient of friction between the mating surfaces, not by glue or screws.
Why this is interesting
You click a phone case together and it stays, but have you ever wondered why it doesn't just fall apart? That satisfying 'snap' is the result of a tiny plastic hook bending just enough to lock in place.