The Invention of the Phillips Head Screw

A 1936 patent for a cross-shaped screw head designed to keep a screwdriver centered and prevent it from slipping during high-speed assembly.

What it covers

The patent describes a screw with a cruciform, or cross-shaped, recess in the head. This shape allows a matching screwdriver tip to self-center, meaning the tool naturally stays in the middle of the screw head as it turns. By increasing the surface contact area between the tool and the screw, it allows for higher torque without the screwdriver slipping out of the slot. This design was specifically engineered to be used with power-driven tools on assembly lines.

What it doesn't cover

• —Does not cover standard flat-head or slotted screws.
• —Does not cover hex-key or Allen-style internal drive systems.
• —Does not cover square-drive or Robertson head screws.
• —Does not cover external bolt heads that require a wrench.

The clever bit

The genius lies in the tapered cross shape, which forces the screwdriver to center itself automatically, turning the act of driving a screw into a self-aligning process.

Why it matters

This design solved a major bottleneck in early 20th-century manufacturing. Before this, slotted screws were prone to 'cam-out,' where the screwdriver slips out of the slot, damaging the product and slowing down assembly lines. It became the industry standard for mass production, particularly in the automotive and aircraft industries.

Real-world examples

• 1.Most consumer electronics assembly
• 2.Automotive manufacturing fasteners
• 3.General household construction screws
• 4.Furniture assembly kits