PEM RT Free-Running Self-Clinching Locknuts
Free-running self-clinching locknuts — the screw spins freely until clamp load is applied, and the nut exerts no torsional resistance once that load is removed — unified .112-40 to .313-18 and metric M3 to M8, installable with the same mounting holes and tooling as standard S-series clinching nuts.
Last updated: 2026-11
Specifications
PEM RT free-running locknuts solve a specific assembly problem: you want a permanently mounted nut that resists vibration, but you do not want prevailing-torque friction while the screw is being run down. The RT locking feature lets the screw turn freely until clamp load is applied; if the load is removed the nut offers no torsional resistance until clamp load returns. The collected bulletin includes a transverse-vibration clamp-load comparison against a plain S nut, a split ring lock washer and a threadlocker — the context in which free-running locking earns its place. Like all clinching nuts it presses into a controlled mounting hole and becomes an integral, non-rotating part of the sheet, back side flush or sub-flush. It reuses the same mounting hole and installation tooling as the standard S nut, reusability is unaffected by the number of on/off cycles, and it is rated for steel or aluminum sheets of HRB 80 (HB 150) or less. Part-number structure: S - RT632 - 1 - ZI (series, thread code, shank code, finish).
| Type | Free-running locknut: free rotation until clamp load; no torsional resistance once the load is removed; locking reusability unaffected by on/off cycles |
|---|---|
| Unified thread range | .112-40 (#4-40), .138-32 (#6-32), .164-32 (#8-32), .190-32 (#10-32, stainless RT032), .250-20 (1/4-20), .313-18 (5/16-18) |
| Metric thread range | M3 x 0.5, M4 x 0.7, M5 x 0.8, M6 x 1, M8 x 1.25 |
| Shank codes (sampled) | #4-40: 0 = .030/.030, 1 = .038/.040, 2 = .054/.056 in. (A max / hole in sheet min); M3: 0 = .77/.8, 1 = .97/1, 2 = 1.38/1.4 mm; 1/4-20: 1 = .054/.056, 2 = .087/.090 |
| Unified geometry (C / E / T, min sheet, edge) | #4-40: .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 (C / E / T, min sheet, edge) | M3: 4.22 / 4.2 / 6.35 / 1.5 / 4.8; M4: 5.41 / 5.38 / 7.87 / 2 / 6.9; M5: 6.35 / 6.33 / 8.64 / 2 / 7.1; M6: 8.75 / 8.73 / 11.18 / 4.08 / 8.6; M8: 10.5 / 10.47 / 12.7 / 5.47 / 9.7 (mm) |
| Panel limits | Steel or aluminum sheets HRB 80 / HB 150 or less; same mounting hole and installation tooling as standard S nuts |
| Performance (sampled, RT440 / RTM3, shank code 1) | 5052-H34 aluminum: 1500–2000 lbs installation, 90 lbs pushout, 10 in.-lbs torque-out (M3: 6.7–8.9 kN / 400 N / 1.13 N·m); cold-rolled steel: 2500–3500 lbs, 125 lbs, 15 in.-lbs (M3: 11.2–15.6 kN / 550 N / 1.7 N·m) (collected CL performance table) |
| Back side | Flush or sub-flush after installation |
| MOQ / lead time | Not owner-confirmed for this family — confirmed at quotation |
Materials
- Per RFQ — the collected bulletin tables cover geometry; material/finish codes follow the S-series designation system (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 (PEM RT Free-Running 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
Free-running vs prevailing-torque — which clinching locknut do I need?
If your assembly sequence runs the screw at speed through a long grip or into a hard-to-reach boss, prevailing-torque friction slows every install and can twist thin panels; a free-running RT spins down with no resistance, so the locking only exists under clamp load. The collected bulletin also notes RT reusability is not affected by the number of on/off cycles, which matters for serviceable covers. If you need residual friction with the screw loose — for example to keep a nut from backing off a joint that is rarely at full clamp — quote a prevailing-torque type instead (SL or HNL).
What does the shank-code ladder change?
Shank code selects the clinching shank length against your sheet thickness: a thicker sheet needs the longer shank so enough material cold-flows into the clinch. The collected table lists an A-max/hole-size pair per code — for #4-40, code 1 is .038 shank into a .040 hole and code 2 is .054 into .056. Pick the code whose recommended minimum sheet matches your panel and keep the code in the part number; the mounting hole changes with it.
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