Carbon Steel Round Welded Nut, Cylindrical Welding Nut

Core Features

Projection Welding Configuration – Three or more precision weld projections are formed on the welding face of the nut to concentrate electrical current and heat during the resistance welding process. The projections flatten as the weld forms, creating a permanent attachment between the nut and the workpiece.

Round Cylindrical Body – The nut body features a circular cross-section with a round base design that distributes clamping load across the bearing surface. The round configuration is suited for confined areas due to its diameter relative to thread size.

Internal Threaded Bore – The central bore contains pre-formed internal threads that accept standard bolts or screws. Thread classes include 6H for metric specifications and Class 2B for unified standards. The thread provides load-bearing capability in sheet metal that is too thin to tap.

Unplated Finish – The component is supplied without surface coating, with a plain finish that is typically protected with light oil to prevent corrosion during storage prior to welding.

Product Characteristics

The fastener is manufactured in accordance with dimensional and mechanical specifications for projection weld nuts. The cylindrical body is dimensioned with an outer diameter that provides adequate bearing surface while maintaining a compact profile relative to thread size. The weld projections are formed on the welding face with controlled height and geometry to ensure consistent heat concentration and weld formation during resistance welding.

Material composition is regulated to meet welding quality requirements. Low-carbon steel grades (such as C1010) with carbon content under 0.30 are typically used for weld nuts, providing material properties that support weld formation while maintaining mechanical strength for the threaded connection. Material selection directly affects weld quality, with pre-welding surface conditions influencing fusion consistency.

The unplated finish allows direct contact between the nut projections and the workpiece surface during welding, maximizing electrical conductivity and heat concentration at the projection points. For applications requiring corrosion resistance, surface treatment can be applied post-welding or through alternative material selection.

Application Scenarios

Automotive Sheet Metal Assembly – Applied in body-in-white structures, engine bay systems, chassis reinforcement brackets, and seat frames where permanent threaded attachment points are required on sheet metal panels. The weld nut eliminates the need for tapping operations on thin-gauge materials.

Industrial Equipment and Appliance Manufacturing – Used in machinery enclosures, appliance housings, HVAC components, and racking systems where spot welding provides efficient attachment and captive threads are required for subsequent assembly.

Metal Fabrication and Structural Assembly – Employed in fabricated metal components where permanent threaded connections are specified and where welding provides vibration-resistant attachment compared to mechanical fastening methods.

Space-Constrained Installations – The round configuration is suited for confined areas where orientation of the nut during welding is a consideration. The cylindrical design accommodates installation in limited-space assemblies.

Customization Options

Specifications and configurations can be adjusted based on application requirements. Material grades include carbon steel grades for general applications and stainless steel grades for corrosion-resistant requirements. Surface treatments are selectable according to environmental exposure conditions, including zinc plating with various chromate finishes, zinc flake coating, nickel plating, and phosphate coating. Thread sizes and dimensional specifications can be matched to application requirements.

Frequently Asked Questions

Q: What is the purpose of the weld projections?
A: The weld projections are small raised dimples on the welding face that concentrate electrical current and heat during resistance welding. As the fastener material softens due to heating, the applied force causes the projections to flatten as the weld forms, creating a permanent bond between the nut and workpiece.

Q: What welding methods are compatible with this product?
A: Projection welding and resistance welding are the primary methods used. Projection welding concentrates current at the projection points, where the contact area between the electrode and nut and between the workpiece and electrode is greater than at the projections, causing heating to occur at the projection locations.

Q: Can these nuts be reused after welding?
A: The welded configuration is intended for permanent installation. Once welded, removal typically requires destructive methods such as grinding or cutting. The internal thread remains usable for component attachment throughout the service life of the assembly.

Q: What is the recommended tightening torque for fasteners used with these nuts?
A: Tightening torque values are determined by the internal thread size, fastener grade, and application load requirements. Torque specifications should be obtained from engineering standards or calculation methods defined in fastener design guidelines, considering friction conditions influenced by surface treatment and lubrication.

Q: Are these nuts available in stainless steel?
A: Yes. Stainless steel grades such as 300 Series stainless steel (including 303 and 18-8) are available for corrosion-resistant applications. Stainless steel weld nuts are typically passivated per ASTM A380 after manufacturing.

Q: What is the typical tensile strength of carbon steel weld nuts?
A: For low-carbon steel weld nuts (e.g., C1010), typical mechanical properties include tensile strength of approximately 60,000 psi and yield strength of approximately 30,000 psi. Strength properties vary based on material grade and heat treatment specifications.

Installation Considerations

Pre-weld surface preparation should include removal of oil, grease, and oxide layers from the nut contact area and workpiece surface to support weld consistency. The workpiece hole size should match the nut specifications to ensure proper alignment and projection contact with the panel. Weld nut push-out resistance is the force required to push the fastener out of the sheet, while torque-out resistance is the torsional strength of the fastener in the sheet.

For unplated nuts, the plain finish is typically protected with light oil to prevent corrosion during storage. This oil should be removed prior to welding if specified by the welding procedure. When welding is performed, the material softens due to heating and the applied force causes the projections to flatten as the weld is formed, forcing the fastener and sheet together.

For applications requiring corrosion protection after welding, surface treatment can be applied post-weld. If welding is specified to occur prior to coating, the weld zone receives protection from the applied coating. Storage conditions should maintain coating integrity by avoiding abrasive contact or impacts that may affect surface quality.