TIGERFASTENERS
Thread-Forming Screws
A trilobular screw has a three-lobed section and displaces material rather than cutting it. No swarf makes it suitable where debris is unacceptable, and the work hardening from displacement gives better pull-out resistance than a cut thread.
Specification options
| Volume range | M1.0 – M5.0 |
|---|---|
| Maximum size | M16 |
| Standards | DIN 7500 · ISO 7085 |
| Materials | see Materials |
| Finishes | see Finishes |
| Minimum order | From 10,000 pcs, depending on the part |
Head styles
Drive types
Choosing the thread
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Trilobular section
Three arc lobes form the thread in sequence, giving smaller contact area and lower driving torque than a full round forming thread.
Where it most often goes wrong
Each of these causes scrapped lots or rework on the floor. None of them is theoretical.
The hole tolerance window is narrower than for self-tapping. Oversize and the thread forms incompletely with no grip; undersize and driving torque climbs sharply, up to head failure. Look the range up for the material — do not reuse self-tapping hole sizes.
Using it in brittle material. Displacement makes the material flow. Cast iron and rigid plastics crack at the hole mouth. Those want a cutting thread instead.
Ignoring the gap between driving and failure torque. That window is narrower than on a machine screw, so automated driving torque has to be established by test rather than copied from machine screw settings.
How length is measured
One rule covers it: if the head sinks into the work, measure overall; if it stays on the surface, measure under the head.
| Head style | Datum | Why |
|---|---|---|
| Countersunk (flat) | Overall length | The head sits flush in the countersink, so it counts |
| Oval (raised countersunk) | Overall to the head diameter | The cone sinks, the dome stays proud; measure to where they meet |
| Pan / round | Under head | The head stays entirely on the surface |
| Button | Under head | Same |
| Hex / hex washer | Under head | Same |
| Socket head cap | Under head | Same |
Full explanation → Where the standards stop at this size → Tolerance stack-up and the screw →
Worth reading before you specify this type
One question per page, with the standard it rests on and the range that standard is valid over.
- Self-tapping, thread-forming or self-drilling: start with the material — No swarf, at the cost of higher driving torque and much tighter hole sensitivity
- Pilot hole size: the screw diameter does not decide it — The window is distinctly narrower than for cutting types — the most common failure point
- Right torque, wrong clamp force — Displacing material means higher driving torque, and less margin to the torsional limit
If your part sits below M6, the micro screw page collects the four constraints that only appear at these sizes.
Enquiries
Thread-Forming Screws come in a lot of combinations. Tell us the item, size, material, finish, annual usage and application, and we will come back on feasibility and lead time. A drawing or a sample is fastest — quoting against the real part saves a great deal of guessing.
Volume range M1.0 – M5.0, standard fasteners up to M16. Minimum order From 10,000 pcs, depending on the part.