Weld nuts
Welded thread retention, projection-welding mechanisms, pilot geometry, and source-specific material and test limits.
Tags: components, fasteners, nuts, welding
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In Buckeye’s four-projection catalog 1/4-20 weld-nut pair, 2004 has 0.125 in body thickness and 0.094 in pilot height. 2004-1 has 0.156 in thickness and 0.062 in pilot height. Both list a 0.406 in pilot diameter. Those fields describe the supplied nut. Verify the installed seating, weld integrity and fit separately. Buckeye family PDF, pp. 1–2.
Identity and retention
A weld nut provides an internal thread and attaches by welding. Its projections can concentrate resistance heating and collapse during welding. Böllhoff, weld nuts.
Self-clinching instead displaces host sheet and a rivet nut forms a bead behind the sheet. PEM, self-clinching nut description, Böllhoff, RIVKLE brochure, p. 7.
Projection welding and other welding families
Resistance welding passes current through contacting workpieces held under electrode force. In projection welding, raised features concentrate the initial current path and contact. TWI distinguishes this from resistance spot welding, where electrode-tip geometry defines the localized weld area. A projection-welded nut can therefore have multiple intended attachment sites around its thread. TWI, resistance welding, Wang and Zhang, 2017, p. 2194
TWI describes both solid machine-threaded nuts with formed solid projections and sheet-metal forms with embossed projections in an integral flange. Projection collapse makes welding-head follow-up and alignment part of the process behavior. The number and shape of the projections are consequently distinct from the thread designation. TWI, projection-weld nut guidance
Arc welding generates heat through an electric arc between an electrode and the base material. MIG/MAG and TIG belong to that family; they are not names for resistance projection welding. Thus “weld nut” identifies an attachment-oriented fastener, while the actual joint geometry and welding process remain separate technical properties. A resistance-welding guide does not specify an arc-welded attachment. TWI, arc welding
Pilot, body and thread geometry
Buckeye describes its square piloted four-projection nuts as through-hole products. The pilot locates the nut in the sheet hole, while the projections are the intended weld-contact features. Pilot diameter, pilot height, body thickness and thread are separate dimensions. Buckeye, square piloted product description
The following two rows are from Buckeye's branded four-projection square-nut family PDF. Dimensions are inches; the sheet thickness and hole size are not specified by these nut dimensions.
| Product | Thread size | Width A | Body thickness C | Pilot height D | Pilot diameter E |
|---|---|---|---|---|---|
| 2004, long pilot | 1/4-20 | 0.500 | 0.125 | 0.094 | 0.406 |
| 2004-1, short pilot | 1/4-20 | 0.500 | 0.156 | 0.062 | 0.406 |
For both rows, A has tolerance +0.000/−0.011 in., C ±0.008 in., D ±0.005 in. and E +0.000/−0.007 in. The common thread and pilot diameter coexist with different body thicknesses and pilot heights; “short pilot” does not imply an otherwise identical nut. The family specifies C1010 low-carbon steel, a plain finish unless otherwise specified, and Unified Class 2B threads referencing ASME B1.1-2003. These are catalog statements, not confirmation against a later thread-standard edition. Buckeye family PDF, pp. 1–2
Fastener and host material conditions
Buckeye separately lists 2004-1-P13 as C1010 steel with a commercial zinc finish and clear trivalent chromate, while the base family PDF says plain unless specified. The finish suffix therefore changes the documented surface condition. The product page also warns that images normally show plain-finish items; appearance in the catalog image does not identify the supplied finish. Buckeye, 2004-1-P13 specifications
A named experimental example illustrates the separate host and nut conditions. Wang and Zhang used M10 round RN-M10 and square SN-M10 nuts, each with four underside projections; the nut compositions differed. Host sheets were DP590, 1.6 mm, and hot-dip galvanized H340LAD+Z, 2.5 mm. Their DC pedestal welder operated at 1,000 Hz with Class II chromium-zirconium-copper electrodes. These are study conditions, not a schedule for the Buckeye products above. Wang and Zhang, p. 2195, Tables 1–3
Weld assessment and evidence boundaries
For SN-M10 joined to H340LAD+Z, the study's destructive separation distinguished three failure locations. In button-pull fracture, a local weld button pulls out of the base-metal sheet through its full thickness, leaving a hole at the weld. Partial-thickness fracture separates within the sheet thickness; interfacial fracture separates at the nut–sheet faying surface. A torque result alone does not describe all those fracture features. Wang and Zhang, §3.5 and Figs. 7–8, pp. 2198–2200 TWI's guidance likewise distinguishes destructive torque testing from peel or push-off evidence at the projections. Its numerical guide is specifically illustrated for square nuts to BS 7670 welded to 1 mm sheet; it is not a general welding schedule for every nut, coating or sheet thickness. TWI, projection-weld nut guidance
TWI identifies thread splash, body collapse/thread distortion and hole misalignment as distinct process problems. Thread functionality and attachment-weld behavior are therefore separate aspects of the result. Neither a finish name nor an observed weld establishes corrosion life, fatigue performance or reuse capability. TWI, projection-weld nut guidance
Standards, dates and coverage
DIN Media's public records identify DIN 928:2013-12 for square weld nuts and DIN 929:2013-12 for hexagon weld nuts. Their scopes include coarse metric threads M4–M16 and M3–M16, respectively, plus fine threads with nominal diameters 8–16 mm, in product grade A. The December editions correct their May 2013 predecessors. These metric scopes do not describe the inch-thread Buckeye rows above. Full standards were not consulted. DIN 928 record, DIN 929 record
The Buckeye-branded family PDF is served by product-config.net, bears ©2026 and has generation metadata dated October 31, 2026; it exposes no controlled drawing revision. Its generation timestamp and the October 31, 2026 PDT retrieval date do not establish a product-design revision. Buckeye family PDF Wang and Zhang's final article was published December 15, 2017; October 21, 2017 is its advance-publication date. ISIJ final publication record
The examples here do not establish universal welding current, weld time, electrode force, heat input, attachment strength, corrosion life or a customer's qualified process. Host thickness and coating, nut geometry/material/finish, equipment and the particular test remain applicability conditions.