SL TRI-DENT Prevailing-Torque Self-Clinching Locknuts
Prevailing-torque self-clinching locknuts with the TRI-DENT locking feature — friction that is essentially the same whether or not axial load is applied, 3-cycle locking performance, unified #4-40 to 5/16-18 and metric M3 to M10, same mounting hole and tooling as standard S-series clinch nuts.
Last updated: 2026-11
Specifications
SL is the prevailing-torque member of the standard S-series clinching nut family: press it into the same controlled mounting hole with the same tooling, and the sheet cold-flows into the clinch ring so the nut becomes a permanent, non-rotating threaded boss. The TRI-DENT locking feature deforms the thread so the mating screw always meets friction — essentially the same torque value regardless of how much axial load is on the joint — which is what keeps threaded joints tight under vibration. The collected bulletin rates the locking at 3 cycles (tested with steel socket head cap screws of 180 ksi / property class 12.9 and a standard thermal-oxide-and-light-oil finish) and recommends the nut for sheets of HRB 80 (HB 150) or less. After installation the back of the panel is flush or sub-flush. The locking element's shape and position may vary between parts — that is by design, not a defect.
| Type | Prevailing-torque locknut: friction between mated threads increases the force to tighten and loosen; torque essentially independent of axial load |
|---|---|
| Locking performance | 3-cycle locking (collected test condition: 180 ksi / property class 12.9 steel socket head cap screws, thermal oxide and light oil finish); vibration-resistant |
| Unified thread range | .112-40 (#4-40), .138-32 (#6-32), .164-32 (#8-32), .190-32 (#10-32), .250-20 (1/4-20), .313-18 (5/16-18) |
| Metric thread range | M3 x 0.5, M3.5 x 0.6, M4 x 0.7, M5 x 0.8, M6 x 1, M8 x 1.25, M10 x 1.5 |
| Unified geometry (A / hole, C, E, T, min sheet, edge) | #4-40: shank codes 1 (.038/.040), 2 (.054/.056); .166 / .165 / .250 / .070 / .19; #6-32: .1875 / .187 / .280 / .070 / .22; #8-32: .213 / .212 / .310 / .090 / .27; #10-32: .250 / .249 / .340 / .090 / .28; 1/4-20: .344 / .343 / .440 / .170 / .34; 5/16-18: .413 / .412 / .500 / .230 / .38 |
| Metric geometry (shank codes, C, E, T, min sheet, edge) | M3: codes 1 (.98/1), 2 (1.38/1.4); 4.22 / 4.2 / 6.35 / 1.5 / 4.8; M3.5: same codes; 4.75 / 4.73 / 7.11 / 1.5 / 5.6; M4: 5.41 / 5.38 / 7.87 / 2 / 6.9; M5: 6.35 / 6.33 / 8.64 / 2 / 7.1; M6: codes 1 (1.38/1.4), 2 (2.21/2.3); 8.75 / 8.73 / 11.18 / 4.08 / 8.6; M8: codes 1 (1.38/1.4), 2 (2.21/2.3); 10.5 / 10.47 / 12.7 / 5.47 / 9.7; M10: codes 1 (2.21/2.29), 2 (3.05/3.18); 14 / 13.97 / 17.35 / 7.48 / 13.5 (mm) |
| Panel limit | Steel or aluminum sheets HRB 80 / HB 150 or less; same mounting hole and installation tooling as standard S nuts |
| Prevailing torque specs (sampled, 1st thru 3rd cycles) | #4-40 (shank code 1): max 5.75 / min 0.4 in.-lbs; 1/4-20: 35 / 3.75; M3: 0.67 / 0.04 N·m; M10: 12 / 0.8 (collected CL performance table) |
| Performance (sampled, shank code 1) | #4-40 in 5052-H34 aluminum: 1500–2000 lbs installation, 90 lbs pushout, 10 in.-lbs torque-out (cold-rolled steel: 2500–3500 / 125 / 15); M3: 6.7–8.9 kN, 400 N, 1.13 N·m (steel: 11.2–15.6 / 550 / 1.7); M10 aluminum: 22–36 kN, 1760 N, 32.7 N·m (collected CL performance tables) |
| Back side | Flush or sub-flush for screw installation |
| Locking feature | TRI-DENT — shape and position may vary between fasteners |
| MOQ / lead time | Not owner-confirmed for this family — confirmed at quotation |
| Thread code | Max. torque (in.-lbs) | Min. torque (in.-lbs) | Installation, aluminum sheet (lbs) | Pushout, aluminum (lbs) | Torque-out, aluminum (in.-lbs) | Installation, cold-rolled steel (lbs) | Pushout, steel (lbs) | Torque-out, steel (in.-lbs) |
|---|---|---|---|---|---|---|---|---|
| .112-40 (#4-40) | 5.75 | 0.4 | 1500 - 2000 | 90 | 10 | 2500 - 3500 | 125 | 15 |
| .138-32 (#6-32) | 10.5 | 0.8 | 2500 - 3000 | 95 | 17 | 3000 - 6000 | 130 | 20 |
| .164-32 (#8-32) | 18 | 1.2 | 2500 - 3000 | 105 | 23 | 4000 - 6000 | 145 | 35 |
| .190-32 (#10-32) | 21 | 1.65 | 2500 - 3000 | 110 | 32 | 4000 - 9000 | 180 | 40 |
| .250-20 (1/4-20) | 35 | 3.75 | 4000 - 7000 | 360 | 90 | 6000 - 9000 | 400 | 150 |
| .313-18 (5/16-18) | 53 | 4.75 | 4000 - 7000 | 380 | 120 | 6000 - 8000 | 420 | 165 |
| Thread | Max. torque (N·m) | Min. torque (N·m) | Installation, aluminum sheet (kN) | Pushout, aluminum (N) | Torque-out, aluminum (N·m) | Installation, cold-rolled steel (kN) | Pushout, steel (N) | Torque-out, steel (N·m) |
|---|---|---|---|---|---|---|---|---|
| M3 x 0.5 | 0.67 | 0.04 | 6.7 - 8.9 | 400 | 1.13 | 11.2 - 15.6 | 550 | 1.7 |
| M3.5 x 0.6 | 1.2 | 0.08 | 11.2 - 13.5 | 400 | 1.92 | 13.4 - 26.7 | 570 | 2.3 |
| M4 x 0.7 | 2.1 | 0.13 | 11.2 - 13.4 | 470 | 2.6 | 18 - 27 | 645 | 4 |
| M5 x 0.8 | 2.4 | 0.18 | 11.2 - 15.6 | 480 | 3.6 | 18 - 38 | 800 | 4.5 |
| M6 x 1 | 4 | 0.3 | 18 - 32 | 1580 | 10.2 | 27 - 36 | 1760 | 17 |
| M8 x 1.25 | 6 | 0.5 | 18 - 32 | 1570 | 13.6 | 27 - 36 | 1870 | 18.7 |
| M10 x 1.5 | 12 | 0.8 | 22 - 36 | 1760 | 32.7 | 32 - 50 | 2020 | 36.2 |
Materials
- Per RFQ — the collected bulletin tables cover geometry; material/finish follow the S-series designation codes (e.g. ZI in the collected part-number examples)
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (SL TRI-DENT Prevailing-Torque Self-Clinching Locknuts) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Why choose prevailing torque over a free-running locknut?
Prevailing torque keeps resisting rotation even when the joint is not under clamp load — the collected bulletin states the torque value is essentially the same whether or not axial load is applied. That is what you want on joints that see vibration while rarely or never fully clamped, or where a loose screw spinning off is unacceptable. The cost is assembly speed: every install and removal works against friction, and the bulletin rates the locking for 3 cycles (its test used class 12.9 screws). For high-cycle service or fast automated rundown, a free-running type is the better fit.
Does the SL change my mounting hole or tooling versus a plain clinch nut?
No. The collected bulletin states SL uses the same mounting hole and installation tooling as the standard S nut, and the geometry table per thread size (C, E, T, minimum sheet, edge distance) matches the S-series ladder — for example #4-40 at C .166 / E .165 / T .250 with a .070 in. minimum sheet. The TRI-DENT feature works inside the thread, not on the clinch.
What should an RFQ for these self-clinching standoffs state?
State the series (CFSO steel, CFSOS stainless, or CFSOA aluminum), thread size (for example #10-32 or M4 x 0.7), body size (small or large), nominal length L, sheet material, thickness and hardness, and quantity per size — plus destination country. Commercial terms are confirmed at quotation.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support