A tapping screw whose thread profile, often trilobular in cross-section, cold-forms an internal thread as it is driven into a pilot hole in ductile metal or plastic. Because nothing is cut away, the formed thread is work-hardened, fits with zero clearance and resists vibration loosening, and there are no chips to clean out of the part. Pilot hole size is critical: too small and drive torque climbs until the screw twists off, too large and the thread strips.
Swap the housing over to thread-forming screws and we can kill the tapping operation on the die casting.
Also heard as
- thread-rolling screw
- trilobular screw
- Taptite
Do not mix it up with
- Tek screw: A self-drilling Tek screw makes its own hole with a drill point; a thread-forming screw needs a pilot hole already there.
Related terms
Tek screw
A self-drilling screw with a drill-bit point that bores its own hole in steel and then threads it in one pass.
Screw
An externally threaded fastener tightened by turning its head, into a tapped hole or a thread it makes itself.
Percent thread
How deep an internal thread is compared with full theoretical depth, set mainly by the tap drill size.
Thread stripping
Failure where the threads of a nut, tapped hole or bolt shear off instead of the bolt breaking.