CamOut and other screw fastening problems

With conical drives such as Phillips and Pozidriv, the drive geometry results in a force that attempts to press the drive onto the screw head when the torsional forces are transmitted. This is the CamOut force. CamOut forces can cause the tip of the blade to slide out of the screw head or even damage the screw in the case of screwdriving tools with a slotted profile. Colloquially, it is also said that the screw is turned round.

Slipping out of the screw also poses a risk of injury to the user and the workpiece. Painted surfaces, for example, can be scratched very quickly. Slotted and cross-head profiles (PH, PZ) are particularly known for this.

Other possible fastening problems

Fastening with hexagonal profiles

In the case of a hex profile, the force only acts on the edges of the six corners. This often damages the screw head, making it unusable. Due to the narrow lines of force, the transmissible torques are relatively low in proportion to the effort applied. This is where the TORX® profile exhibits a significantly more positive ratio between effort and torque. The large surfaces to apply force make work significantly easier.

Reduced notch effect when tightening the screw

One danger for screws is high stress concentration occurring when the screw is tightened. This generally occurs with hex drive profiles and can cause warping in the tool and screw. The TORX®'s wave profile and its consequential lack of square edges minimise stress concentration. This prevents damage and extends the lifespan for the screw and tool. The wave profile also ensures a small tolerance backlash between the fastening tool and the screw. The result is a significantly improved traction. In the case of TORX PLUS®, the traction is improved yet again thanks to an angle of attack down to almost 0° and a greater core area. This allows a higher torque to be applied and the screw and fastening tool are protected, thus increasing their lifespan yet again.