Product Summary

Longze High-Precision Square Weld Nuts (DIN 928 / ISO 21670) are specialized fasteners designed to be permanently fused to sheet metal parts via resistance welding.

Manufactured in Yongnian, China, our weld nuts feature four precision-engineered welding projections that ensure uniform heat distribution and a high-strength bond. Whether for

automotive chassis components, industrial enclosures, or metal cabinetry, Longze square weld nuts provide a heavy-duty threaded anchor that will not loosen or spin under high-torque conditions.

• ✔ Uniform Projection Height: Our multi-station cold-heading process ensures each of the four welding bosses is identical in height, preventing "one-sided" welding and ensuring 100% joint integrity.

• ✔ Spatter-Resistant Threads: Precision-tapped internal threads are designed to minimize the risk of weld spatter adhesion, ensuring easy bolt engagement after the welding process.

• ✔ Optimized Carbon Content: We use low-carbon steel (C1008/C1010) specifically selected for its superior weldability, preventing brittle heat-affected zones (HAZ).

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• Standards: DIN 928, ISO 21670, BS 4933.

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• Thread Range: M4 to M16.

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• Shape: Square Body with 4 Welding Projections.

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• Material: Weldable Low Carbon Steel | Stainless Steel 304 & 316.

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• Surface Finish: Plain/Oiled (Best for welding), Zinc Plated (Note: Plating must be removed or avoided at weld points).

Mechanical Properties & Material Standards

• Matching the steel grade to the structural requirements of the transmission line.

• Material Grade	Carbon Content	Tensile Strength	Weldability Rating	Environmental Suitability
  Low Carbon Steel	0.08 - 0.13%	350 - 450 MPa	Excellent	General Sheet Metal
  Stainless 304	< 0.08%	500 - 700 MPa	Good (Requires SS settings)	Food / Corrosive Areas
  Stainless 316	< 0.08%	550 - 750 MPa	Good	Marine / Chemical

Standard Cross Arm Dimensions

• Common angle steel configurations for standard utility pole mounting.

• Thread Size (D)	Nut Width (s)	Total Height (m)	Projection Height (h)	Weight (kg/1000pcs)
  M6	10 mm	5.0 mm	0.80 mm	2.50 kg
  M8	13 mm	6.5 mm	1.00 mm	5.20 kg
  M10	16 mm	8.0 mm	1.20 kg	10.50 kg
  M12	19 mm	10.0 mm	1.40 mm	17.80 kg

Surface Treatment & Weld Quality

• Ensuring 30+ years of service life in corrosive environments.

• Finish Type	Process	Weld Compatibility	Resistenza alla corrosione	Best Application
  Plain (Oiled)	Cold Forged	100% (Native)	Low (Requires Post-Paint)	Automotive E-Coat Lines
  Zinc Plated	Electrolytic	Low (Fumes Risk)	Moderate	Post-Weld Plating
  SS Polished	Mechanical	High (Inert Gas)	Extreme	Medical / Food Equipment

Avoid Pitfalls:

• Projection Collapse: If welding pressure is too high before current flows, the projections can collapse, leading to a weak surface-only weld. Longze projections are designed with a specific "aspect ratio" to resist premature collapse.

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• Pilot Hole Misalignment: We ensure the pilot diameter (the part that sits in the sheet metal hole) is within ±0.1mm tolerance to prevent the nut from shifting during the robotic welding cycle.

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• Thread Distortion: Excessive welding heat can distort internal threads. We recommend using copper-alloy welding electrodes and optimized timing to keep the thread geometry within 6H tolerance.

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Perfect Fit Assembly:

• Automated Feeding: Our DIN 928 nuts are sorted via optical sensors to ensure zero "half-formed" parts, making them perfect for high-speed vibratory bowl feeders and robotic assembly.

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• Electrode Selection: For the best results, use flat-faced electrodes that cover all four projections simultaneously to ensure balanced current flow.

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Quality Control & Logistics:

• ISO 9001 Certified: 5-step QC including "Push-out" and "Torque-out" destructive testing on sample welds, thread gauge verification, and raw material chemical analysis.

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• Sea-Worthy Packaging: Packed in 25kg heavy-duty bags or cartons, plastic-lined to prevent flash rust during maritime transit, and palletized for export from our Yongnian facility.

• Q: Why do you suggest Plain/Oiled finish instead of Zinc? A: Welding through zinc plating creates toxic fumes and can contaminate the weld pool, leading to porosity. Most professional automotive lines use plain nuts and paint the entire assembly afterward.

• Q: Can these be used on curved surfaces? A: The square base is best for flat sheet metal. For curved surfaces, we recommend our DIN 929 Hex Weld Nuts, which offer a better fit on slight radii.