Screw Drive Types: Phillips, Pozidriv, Torx, Hex & Robertson Compared

Torque Transfer Efficiency & Cam-Out

Cam-out is the process where a drive bit slips out of the screw head under high rotational torque. While the Phillips drive was intentionally engineered in the 1930s to cam out before over-torquing factory assembly lines, modern automated tools require maximum torque transfer without slippage.

• Phillips (PH): Tapered cross-recess prone to cam-out at high torque.
• Pozidriv (PZ): Features secondary radial ribs between the cross arms; reduces cam-out significantly compared to standard Phillips.
• Torx / Star (T-Drive): 6-lobe design with a zero-degree drive angle; virtually zero cam-out, extends bit life up to 10x.
• Robertson (Square): Popular in North America; self-holding on driver bit with excellent torque retention.