How do square welding nuts achieve high-strength threaded connections on thin plates?
Publish Time: 2025-11-04
In modern manufacturing, thin plate structures are widely used in automotive bodies, electrical cabinets, appliance housings, and automated equipment frames due to their advantages such as lightweight, low cost, and easy forming. However, the limited thickness of thin plate materials makes it difficult to directly machine reliable and durable internal threads. Traditional tapping methods easily result in shallow threads, low strength, easy stripping, and even penetration of the plate, failing to meet the connection requirements of repeated disassembly and assembly or bearing heavy loads. Against this backdrop, square welding nuts achieve high-strength threaded connections on thin plates by cleverly integrating metal forming, welding processes, and structural mechanics, transforming the originally fragile thin plate area into a stable and reliable threaded connection point.The core design of square welding nuts lies in their body being made of high-strength steel, with a complete and standard internal thread pre-machined inside, and an external positioning and welding structure optimized for welding. When precisely placed in the pre-punched hole of the thin plate, the bottom of the nut is fused to the thin plate under localized high temperature through projection welding, energy storage welding, or robotic automated welding processes. This process not only firmly anchors the nut to the plate surface but also creates a connection strength far exceeding that of mechanical interlocking through metallurgical bonding. After welding, the thin plate itself no longer bears the thread function; instead, the nut body provides all the thread load-bearing capacity, fundamentally solving the problem that thin plates cannot "self-generate" high-strength threads.The square structure plays a crucial role in this process. Its straight-edge design not only facilitates automated feeding and positioning, preventing rolling deviation before welding, but also provides excellent torsional resistance after welding. When the external bolt is screwed in and torque is applied, the square edges effectively embed into the periphery of the hole in the thin plate, converting the rotational torque into shear resistance on the plate, preventing the nut from rotating or loosening under stress. This geometric advantage makes it particularly outstanding in applications requiring frequent disassembly and assembly or subjected to vibration loads.Furthermore, square welding nuts typically have positioning protrusions or storage grooves at the bottom. These tiny structures melt instantly during welding, forming a uniform weld nugget, ensuring weld strength while preventing molten metal from flowing into the threaded hole and causing blockage. Meanwhile, the nut's body thickness is significantly greater than that of the thin plate, with ample internal thread depth and complete tooth profile, enabling full engagement with standard bolts and significantly improving tensile and shear resistance. Even during repeated tightening and loosening cycles, thread wear only occurs within the high-hardness nut, without damaging the base material, ensuring a long connection lifespan.Material selection is equally crucial. High-quality welded nuts use tempered or surface-hardened alloy steel, balancing toughness and hardness to prevent cracking during welding and ensure thread wear and corrosion resistance. Some products also offer galvanizing and Dacromet coatings for corrosion protection, suitable for long-term use in humid or corrosive environments.From a manufacturing efficiency perspective, welded nuts achieve "one-piece molding, ready to use immediately." No subsequent tapping, threading, or nut post is required, significantly shortening assembly time and making them particularly suitable for mass automated production. On robotic welding production lines, square nuts can be precisely and quickly inserted, seamlessly integrating with stamping, bending, and other processes, improving overall manufacturing consistency and yield.In summary, square welding nuts successfully construct stable, durable, and reusable high-strength threaded connections on thin plates by combining high-strength pre-threaded components with thin plate metallurgy, enhancing torsional and anti-rotation resistance through their geometry, and achieving reliable anchoring through advanced welding technology. They are not merely fasteners, but also bridges the functionalization of thin plate structures, allowing lightweight materials to support robust connections and achieving a perfect balance between precision and strength.
