Pozidriv

The Pozidriv (or SupaDriv) is a type of screw head and screwdriver, jointly patented by the "Phillips Screw Company" and American Screw Company. The name is thought to be an abbreviation of "pos"itive "driv"e. It is similar in appearance to the classic Phillips cross-head, but in fact is substantially different. The largest advantage it offers is that, when used with the correct tooling in good condition, it does not cam out, allowing great torque to be applied.

Differences

The differences lie in the way that the drivers are machined. The Phillips driver has four simple slots cut out of it, whereas in the case of the Pozidriv, each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided in the case of Pozidriv, and tapered in the case of Phillips. The pozidriv has four additional points of contact, and does not have the rounded corners that the Phillips screw drive has. In ANSI standards it is referred to as "type IA". [cite web|url=http://www.sizes.com/tools/screw_drive.htm|title=screw drive systems]

The pozidriv screw can easily be distinguished by a line embossed in the screw head at 45 degrees to the slots for the driver. Thus, if the driver slots are at 0, 90, 180 and 270 degrees, the marker lines are at 45, 135, 225 and 315 degrees.

Advantages over Phillips type

This design is intended to decrease the likelihood that the Pozidriv screwdriver will slip out, provide a greater driving surface, and decrease wear and tear. [http://www.phillips-screw.com/Comm_Auto_pozidriv.htm Pozidriv page] at Phillips Screw Company] The marker lines on a Pozidriv screwdriver will not fit a Phillips screw correctly, and are likely to slip or tear out the screw head. Phillips screwdrivers will fit in and turn Pozidriv screws, but will cam out if enough torque is applied, potentially stripping the screw.

The chief disadvantage of Pozidriv screws is that they are visually quite similar to Phillips, thus many people are unaware of the difference or do not own the correct drivers for them, and use incorrect screwdrivers. This results in difficulty in unscrewing the screw and in damage to the slot, rendering any subsequent use of a correct screwdriver unsatisfactory.

References

External links

* [http://www.justbrits.com/pozi/pozidriv.html Phillips or Pozidriv?]
* [http://www.hafele.com/us/services/haefele-library/4300.htm What's the difference between Phillips, Pozidrive and Robertson (square) screws?]
* [http://www.wiha.com/index.php/england/informationen_service/service/ratgeber/schraubprofile Overview of common screw head types: Slotted, Phillips, Pozidriv, Torx, Hex, Spanner]