Explore our primary product lineup exported globally, manufactured strictly to meet standard industrial specifications and precision engineering requirements.
Sinsun Hardware, established in 2006, is a premier manufacturer and global exporter of high-strength fasteners. Based in Northern China, we run a massive 30,000 square meter state-of-the-art production plant that serves as one of the largest self-tapping screw and industrial hardware hubs in the region.
Equipped with a 12,000 square meter smart warehouse system housing over 18,000 pallets, we manage a constant capacity of 20,000+ SKUs. Our global distribution network actively exports more than 8,500 shipping containers annually to high-demand regions, including the Middle East, Southeast Asia, South America, and Russia. We pride ourselves on executing vertical manufacturing control—beginning at raw steel selection to the final surface treatments.
In modern industrial assembly, particularly within automotive sheet metal processing and heavy appliance chassis production, securing components to thin-walled materials requires robust, internal threaded connections. Square weld nuts represent the pinnacle of projection welding fasteners, designed to form a permanent, high-strength bond with steel sheets. By utilizing localized electrical resistance welding (projection welding), these fasteners eliminate the risk of thread stripping, loose connections, and structural failure under intense vibrational load.
The four symmetrical corner projections ensure a balanced distribution of electrical current during resistance welding. This uniform energy flow results in clean, localized melting of the projections, fusing the nut perfectly parallel to the sheet metal without distorting the threads or creating visual surface defects.
Equipped with a precise locator pilot (collar), our square weld nuts fit perfectly into pre-punched or pre-drilled holes. The pilot protects the internal threads from weld spatter during the automated robotic cycle, avoiding the need for post-assembly tap cleaning.
Unlike round or hex weld nuts, the square profile provides natural geometric resistance. When embedded in sheet metal pockets or welded flush, the square edges withstand immense tightening torque, eliminating spin-out failures during installation.
Sinsun Hardware manufactures square weld nuts in strict accordance with dynamic global standards, supporting both metric and imperial measurements. Below is our standard dimension chart targeting the widely specified DIN 928 (Metric Square Weld Nuts) and ASME B18.2.2 criteria:
| Standard Thread Size | Width Across Flats (s) | Nut Height (m) | Pilot Diameter (d2) | Pilot Height (h) | Projection Height (g) |
|---|---|---|---|---|---|
| M4 (DIN 928) | 7.0 mm | 3.5 mm | 5.0 mm | 0.6 mm | 0.4 mm |
| M5 (DIN 928) | 9.0 mm | 4.2 mm | 6.0 mm | 0.8 mm | 0.6 mm |
| M6 (DIN 928) | 10.0 mm | 5.0 mm | 7.5 mm | 0.8 mm | 0.7 mm |
| M8 (DIN 928) | 14.0 mm | 6.5 mm | 10.0 mm | 1.0 mm | 0.9 mm |
| M10 (DIN 928) | 17.0 mm | 8.0 mm | 12.5 mm | 1.2 mm | 1.15 mm |
| M12 (DIN 928) | 19.0 mm | 9.5 mm | 14.8 mm | 1.4 mm | 1.25 mm |
Sinsun Hardware offers an optimized supply chain that translates directly into cost efficiency, reliable lead times, and uncompromised metallurgy. Our integrated production ecosystem controls quality from the raw steel rods to the final packaged containers.
We source premium quality wire rods exclusively from verified partners such as XING TAI Steel. This ensures a consistent carbon composition and steel micro-structure. We perform in-house spheroidizing annealing and precision wire drawing in our own plant, which optimizes the steel for the cold heading process and prevents microscopic fracturing during forming.
Our production floor features advanced multi-station cold heading machinery imported from Germany and tooling layouts engineered in Taiwan. This tooling enables our weld nuts to maintain a dimensional tolerance of ±0.02mm and achieves an exceptionally smooth surface finish (Ra ≤ 0.4μm), which is vital for high-speed automated robotic welding lines.
We operate four in-house heat treatment lines (expanded in 2025). This capacity enables us to control the hardening processes (HRC 28-32) to prevent thread deformation under stress. For corrosion protection, we offer zinc plating, black oxide, and eco-friendly E-coating capable of withstanding 1,000+ hours of continuous salt spray testing.
Explore our journey of expansion and technological upgrades, building a global logistics and manufacturing network step-by-step.
Sinsun was founded with a clear objective: to build a state-of-the-art factory focused on precision self-tapping screws and core structural fasteners. This early specialization built the engineering foundation for our complex projection weld nut production lines.
Expanding beyond domestic supply, Sinsun established its dedicated export division. Our high-grade fasteners began entering international industrial supply chains, setting our standards to comply with European and American specifications.
Sinsun integrated four high-capacity spheroidizing furnaces and wire drawing operations inside our plant. This allowed us to execute total micro-structural control from the wire rod phase, ensuring consistent weldability and structural stability.
We installed German multi-station cold heading systems and precision tooling. This upgrade expanded our manufacturing capabilities to include complex automotive-grade projection weld nuts and specialized drill tail fasteners.
Sinsun reached a record annual output of 36,000 tons, exporting over 1,100 containers globally. This expansion validated our capability to handle bulk contracts for global OEM manufacturers.
We inaugurated our 12,000 square meter smart warehouse system, maintaining a dedicated 1,200 square meter ready-stock zone. This system ensures fast lead times and flexible shipping windows for regular procurement schedules.
To guarantee reliable production and on-time shipment schedules, Sinsun added four automated, controlled-atmosphere heat treatment lines. This ensures highly uniform case hardening (HRC 28-32) and decarburization-free components.
Square weld nuts are dynamic fasteners used in automated assemblies. Because they are welded directly to the base frame, they provide robust internal threads in blind spots where traditional nuts cannot be manually held or tightened.
Used on car chassis, seat frames, and structural columns. Sinsun's weld nuts withstand high vibrational loads and integrate seamlessly into robotic assembly lines using automatic bowl feeders.
Widely applied in washing machines, refrigeration housings, and HVAC cabinets. The four-projection design guarantees strong sheet-metal adherence without burning or warping thin panels.
Ideal for server racks, control cabinets, and heavy transformer panels. The clean thread design prevents electrical grounding failures caused by excess weld spatter.
For outdoor renewable energy infrastructure, we supply heavy zinc-plated and stainless steel square weld nuts that resist rust and degradation in humid environments.
Our ISO 9001:2015 certified manufacturing plant subjects every batch of square weld nuts to 12+ stringent quality checks, including:
Read our technical answers regarding projection welding nuts, manufacturing options, and procurement logistics.
A pilot weld nut features a raised circular ring (collar) surrounding the thread hole, which aligns directly with the pre-drilled sheet metal hole. This alignment collar prevents sheet metal shifts during robotic placement and shields the internal threads from weld spatter. Non-pilot versions lack this flange and are typically used in manual alignment jigs or shallow pocket applications.
For welding integrity, low carbon steel grades (such as C1008, C1010, or Q235) are selected. These grades are chosen for their lower carbon equivalents, which prevents martensitic brittleness around the heat-affected zone (HAZ). Additionally, our in-house spheroidizing annealing process guarantees uniform carbon dispersion, which stabilizes the resistance during electrical projection welding cycles.
Yes. Because we control the dimensional tolerance of our flats and projection height strictly within ±0.02mm, our square weld nuts feed smoothly into pneumatic automatic weld feeding machines. The dimensional consistency prevents feeder jams and keeps production lines running efficiently.
With a production floor spanning 30,000 square meters and a 12,000 square meter warehouse, standard orders can ship within 20 to 30 days. For custom OEM/ODM fasteners, our technical team generates 3D design previews and prototype molds within 7 to 10 days, followed by bulk production once approved.
Yes, we offer fully customizable OEM packaging options. These range from bulk industrial boxes (15kg/25kg) and wooden pallets to heat-sealed retail bags and customized barcode boxes, managed by our professional packaging team.
Sinsun Hardware welcomes global partners, distributors, and quality inspectors to visit our manufacturing facilities. Each month, we host audits from global clients, demonstrating our end-to-end manufacturing process and physical laboratory testing tools.
Looking for a reliable manufacturer of square weld nuts or custom structural fasteners? Contact our technical sales team for dimension sheets, material certificates, and a fast price quotation.
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