Galvanized through-hole rivet nuts consist of two parts: the "through-hole riveting body" and the "galvanized protective layer", and the synergy between them is the foundation of their core competitiveness. The through-hole riveting body is usually processed from high-quality carbon steel (such as 1018, 1020 medium carbon steel) or alloy steel, and its structure includes three core components: a through-threaded hole, knurled teeth, and a flange: The through-threaded hole is the key difference between it and blind-hole rivet nuts. During installation, it allows bolts to completely penetrate the nut, making it suitable for scenarios requiring "double-sided fastening" (such as the connection between equipment casings and internal brackets) and avoiding the limitation of "single-sided force bearing" of the blind-hole structure; The knurled teeth are distributed on the outer side of the riveting section of the nut. During the riveting process, the teeth will embed into the workpiece surface to form a "mechanical bite", which greatly improves the anti-loosening ability of the connection. It is especially suitable for scenarios with frequent vibrations (such as automobile instrument panels and power tool casings); The flange can increase the contact area between the nut and the workpiece, preventing the workpiece from denting or deforming due to excessive local pressure during riveting. At the same time, it can also play a certain sealing role, reducing the entry of dust and moisture into the connection gap.
As the "protective core", the galvanized coating is not a simple surface coating, but a metal protective layer formed by hot-dip galvanizing or electro-galvanizing processes. The coating thickness is usually controlled at 5-15μm (adjusted according to the needs of the application scenario). The coating formed by the hot-dip galvanizing process has stronger adhesion and more uniform coverage, making it suitable for outdoor or humid environments; The electro-galvanizing process can achieve more precise coating control, making it suitable for precision components with high requirements for appearance accuracy. Regardless of the process used, the core value of the galvanized coating is reflected in three aspects: First, efficient rust prevention. The zinc layer can react with oxygen and moisture in the air to form a dense protective film of zinc oxide and zinc hydroxide, blocking the contact between the substrate and corrosive media. Even if there are small scratches on the coating, the "sacrificial anode effect" of zinc can corrode first, protecting the nut body from rust. According to neutral salt spray tests, high-quality galvanized through-hole rivet nuts can withstand 48-96 hours without red rust, far exceeding ungalvanized carbon steel nuts (usually only 8-12 hours); Second, improved wear resistance. The hardness of the galvanized layer is higher than that of the carbon steel substrate, which can reduce the wear of the nut during transportation and assembly, and avoid rust prevention failure caused by surface damage; Third, enhanced electrical conductivity. Zinc has better electrical conductivity than ordinary anti-rust paint. In scenarios such as grounding connections of electronic equipment and fastening of conductive components, galvanized through-hole rivet nuts can meet both fastening and conductive needs without the need for additional conductive gaskets.
Combined with the characteristics of the riveting process, the application advantages of galvanized through-hole rivet nuts are further amplified. The riveting process does not require pre-tapping like traditional threaded connections, nor does it rely on high-temperature welding operations. It only needs to press the nut into the prefabricated hole of the workpiece (the hole diameter is slightly smaller than the diameter of the nut's riveting section) through a riveting machine, and use the plastic deformation of the workpiece and the engagement of the nut's knurled teeth to complete the fastening. The entire process takes only 5-20 seconds and requires no subsequent processing (such as deburring or repainting). This "one-step" installation method makes it particularly suitable for mass production scenarios—such as the mass assembly of mobile phone charger casings and the assembly line production of auto parts—greatly reducing labor and time costs. At the same time, galvanized through-hole rivet nuts after riveting have stable connection strength: taking the M5 specification carbon steel galvanized through-hole rivet nut as an example, its tensile strength can reach 25-35kN, and its shear strength can reach 15-20kN, which fully meets the fastening needs of scenarios such as electronic equipment and furniture; Moreover, since the threaded hole runs through the entire nut, bolts can pass through from both sides, making it suitable for scenarios where "both sides of the workpiece need to be connected" (such as the connection between shelf laminates and columns, and the fixing of front and rear covers of equipment), which is impossible for blind-hole rivet nuts.
From the perspective of practical application scenarios, the adaptability of galvanized through-hole rivet nuts covers the core needs of multiple industries. In the electronics and communication industry, they are often used for splicing router casings and fixing internal components of printers: On the one hand, the riveting process will not damage the precision structure of electronic equipment, avoiding component damage caused by high welding temperatures; On the other hand, the rust resistance of the galvanized coating can cope with the humid environment during long-term use of the equipment (such as office air-conditioned rooms and the plum rain season in southern China), preventing casing loosening and poor contact of internal circuits caused by nut rust. In the automobile manufacturing industry, galvanized through-hole rivet nuts are key connectors for automotive interiors (such as center console brackets and door trim panels) and chassis components (such as spare tire holders and fuel tank brackets): Automotive interiors have high requirements for surface flatness, and the surface of the nut after riveting is flush with the workpiece without protrusions; Chassis components are exposed to rainwater and sediment for a long time, and the rust resistance of the galvanized coating can ensure long-term stable connection, avoiding the risk of component falling off caused by nut rust. In the hardware and furniture industry, they are widely used for connecting metal frames of shelves, filing cabinets, and wardrobes: Shelves need to bear weight frequently, and the high tensile strength of galvanized through-hole rivet nuts can ensure that the laminates do not collapse; The connection between the door and cabinet body of filing cabinets and wardrobes requires repeated opening and closing, and the anti-loosening ability of the nut (knurled tooth engagement) can prevent the door from loosening and making abnormal noises due to vibration. At the same time, the rust resistance of the galvanized coating can cope with the humid environment inside the wardrobe (such as moisture after clothes drying).
Compared with other similar fastening components, galvanized through-hole rivet nuts have significant competitive advantages. Compared with ordinary galvanized bolt-nut combinations, they do not require pre-tapping, reducing processes, and the riveted connection is firmer and less likely to loosen due to vibration; Compared with welded nuts, they do not require professional welders, have higher assembly efficiency, and do not cause problems such as welding fumes and deformation, which meets the green production requirements of modern industry. At the same time, the rust resistance of the galvanized coating is better than that of the paint treatment after welding; Compared with stainless steel through-hole rivet nuts, galvanized through-hole rivet nuts (with carbon steel substrates) have lower costs (about 40%-60% lower), and in non-strongly corrosive scenarios (such as indoor environments), their rust resistance is similar to that of stainless steel, with higher cost-effectiveness. They are particularly suitable for mass use in civilian products and mid-to-low-end industrial products.
During use and selection, three key points need to be noted to give full play to its performance. First, select specifications according to the workpiece material and thickness: If the workpiece is made of soft materials such as aluminum alloy or plastic, a model with a smaller riveting section diameter and a larger flange should be selected to avoid workpiece cracking during riveting; If the workpiece thickness is thin (<1mm), a thin-walled nut should be selected to prevent excessive deformation of the workpiece; If the workpiece thickness is large (>5mm), a model with a long riveting section should be selected to ensure sufficient engagement depth. Second, select the galvanizing process according to the application environment: For outdoor and humid environments (such as outdoor shelves and automobile chassis), hot-dip galvanized nuts should be preferred; For precision electronic equipment and indoor scenarios, electro-galvanized nuts can be selected. Finally, control the riveting parameters: The pressure of the riveting machine needs to be adjusted according to the nut specification and workpiece material (for example, the pressure corresponding to M4 nuts is usually 15-25kN). Too little pressure will lead to unstable connection, and too much pressure may damage the nut thread or the workpiece. It is recommended to operate with reference to the parameter table provided by the manufacturer and conduct a pressure test if necessary.
To sum up, galvanized through-hole rivet nuts take "scenario adaptability of through-hole structure + protection of galvanized coating + efficiency of riveting process" as the core, solving the pain points of traditional fastening components such as "complex installation, poor rust prevention, and limited scenarios". As the electronics, automobile, and furniture industries have increasingly higher requirements for assembly efficiency and product service life, galvanized through-hole rivet nuts will further optimize their structural design (such as anti-loose threads and ultra-thin flanges) and coating processes (such as chromium-free passivated galvanizing, which meets environmental standards), continuously expand their application boundaries, and become a core component with both practicality and economy in the field of industrial fastening.
