Carbon Steel 3 Spot Weld Blind Nut, Flanged Closed End Waterproof Weld Nut For Automobile Body

Core Features

Three Spot Weld Projections – Three weld projections are formed on the underside of the flange, enabling attachment through spot welding. The welding principle involves melting the three weld points at high temperature so the weld points are melted onto the workpiece to achieve the welding effect .

Closed-End Sealed Design – The blind bottom encloses the internal thread, creating a sealed connection that prevents water, dirt, oil, or debris ingress. The closed-end design also prevents screws that are too long from passing through the nut.

Flanged Configuration – The flange provides a load-bearing surface that distributes clamping force across the workpiece. The flange underside contains the three weld projections and may include a locating boss for positioning relative to the workpiece hole .

Weld Nut Construction – The nut is designed specifically for welding attachment to sheet metal, creating a permanent, non-removable connection. The projection weld provides accurate positioning and consistent weld strength across all three points .

Product Characteristics

The nut is manufactured with a flanged head and a closed-end barrel. The flange incorporates three weld projections positioned on the underside, typically spaced at defined intervals around the flange circumference. A locating boss may be provided on the flange underside for positioning the nut relative to the workpiece hole.

The weld projections are dimensioned to concentrate welding current and heat during the resistance welding process. The projections melt and fuse to the workpiece surface when welding current is applied, creating a permanent bond between the nut and the panel. The closed end of the nut provides a sealed internal thread cavity that prevents fluid ingress.

Material composition is controlled to meet specified strength and weldability requirements. Carbon steel grades are available for general applications, with material selection affecting weld performance and mechanical properties. Surface treatment options include zinc plating with various chromate finishes, zinc-nickel alloy coating, and phosphate coating.

Application Scenarios

Automotive Body Assembly – Used in vehicle body panels, chassis components, and structural assemblies where watertight threaded attachment points are required and where welding provides permanent, vibration-resistant fastening. The closed-end design prevents fluid ingress through the fastener .

Sheet Metal Fabrication – Applied where load-bearing threads are required in sheet metal that is too thin for tapping. The weld nut provides a permanent threaded insert through welding attachment.

Enclosure and Housing Assembly – Employed in equipment enclosures and housings where sealing against water or dust ingress is specified and where access to the reverse side of the panel is limited.

Structural Component Mounting – Used where components require secure attachment through welding, with the weld nut providing integrated threads for subsequent bolted connections.

Customization Options

Specifications and configurations can be adjusted based on application requirements. Thread sizes include metric dimensions from M3 to M16. Material grades include carbon steel for general applications and stainless steel for corrosion-resistant requirements. Surface treatments are selectable according to environmental exposure conditions, including zinc plating with various chromate finishes, zinc-nickel alloy coating, and phosphate coating.

Frequently Asked Questions

Q: How do the three spot weld projections function?
A: The three weld projections are melted at high temperature during resistance welding, fusing the nut to the workpiece. The welding principle uses electrical current to heat the projections until they melt and bond to the workpiece surface .

Q: What welding methods are compatible with this product?
A: The nut is designed for spot welding using a spot welder. The welding parameters should be set based on material grade, thickness, and equipment specifications. The projection welding process provides accurate positioning with consistent weld strength .

Q: Does the closed-end design provide waterproof sealing?
A: The closed-end barrel creates a sealed internal thread cavity that prevents water, dirt, oil, or debris ingress through the nut. The weld attachment also contributes to the sealing interface when properly welded to the workpiece.

Q: Are these nuts removable after welding?
A: The weld nut is intended for permanent installation through welding. Once welded, removal typically requires destructive methods such as grinding or cutting. This creates a non-removable connection suited for permanent assembly applications .

Q: What is the recommended hole preparation for installation?
A: A locating hole should be punched or drilled in the workpiece to accommodate the locating boss on the nut flange. The locating boss positions the nut relative to the hole before welding .

Installation Considerations

Hole preparation should be performed through punching or drilling to the specified diameter for the locating boss. The nut should be positioned with the locating boss inserted into the workpiece hole and the three weld projections contacting the workpiece surface. Welding parameters should be set based on nut material grade, thickness, and equipment specifications. The welding current should be applied to melt the three weld projections, fusing them to the workpiece surface . Post-weld inspection should verify fusion quality through visual examination. The connection is non-removable once welded . For plated or coated nuts, coating application is typically performed before welding, with welding parameters adjusted to account for coating effects on electrical conductivity.