The Phillips Screw Was Designed to Slip on Purpose

Henry Phillips invented the crosshead screw design in the 1930s specifically for automated assembly lines. Unlike flathead screws that could be overtightened and damage products, the Phillips design intentionally causes the screwdriver to cam out or slip when too much torque is applied. This prevented workers from damaging screws or the materials they were fastening, making it ideal for mass production. The design was a major improvement for manufacturing efficiency and product quality.