The automotive industry stands as a crucial application field for insert nuts. In automotive interiors, the connection between plastic components (such as instrument panels and central control panels) and metal brackets depends on hot-melt insert nuts, which can withstand long-term vibration without loosening. In the high-temperature environment surrounding the engine, stainless steel insert nuts are embedded into heat-resistant plastic parts via the in-mold injection process, ensuring stable fixation of oil pipelines.
The medical device sector imposes extremely high requirements on connection precision and safety. At the junction of plastic handles and metal operating rods in surgical instruments, stainless steel insert nuts implanted by ultrasonic technology are adopted—this not only eliminates the risk of chemical corrosion but also endures the high-temperature environment of repeated disinfection. In the adjustment mechanisms of rehabilitation equipment, self-tapping insert nuts provide reliable threads for plastic brackets, guaranteeing structural safety during patient use.
The consumer electronics industry pursues thinness, lightness, and high performance, making insert nuts core connecting components. The metal frames and plastic middle frames of smartphone casings are connected using brass insert nuts; the conductivity of brass is leveraged to avoid signal interference. The hinge structures of laptops utilize cold-pressed insert nuts, which achieve stable fixation of rotating shafts on thin plastic parts, balancing lightweight design and durability.
The hot-melt installation method is suitable for most thermoplastic plastics. A dedicated heating tool heats the insert nut to the plastic softening temperature (typically 180-220°C), then presses it into the pre-drilled hole under pressure. After cooling, the knurled structure forms a mechanical lock with the plastic. This method boasts high efficiency, making it ideal for mass production, and is widely used in the manufacturing of automotive interior parts.
Ultrasonic installation utilizes high-frequency vibration (15-40kHz) to generate frictional heat at the contact surface between the insert and plastic, completing implantation within seconds. Its advantage lies in a small heat-affected zone, which prevents deformation of plastic parts—making it particularly suitable for installing precision plastic components like smartphone casings, with accurate control over embedding depth and perpendicularity.
The in-mold injection process requires fixing the insert nut to the mold pin before plastic injection; the molten plastic wraps around the insert and cools to form a solid structure. This approach achieves complete integration of the insert and plastic, delivering optimal tensile and torsional performance. It is often employed for lightweight plastic components in the aerospace field, enabling high-strength connection of 0.5mm thin-walled plastic parts.
Cold-press installation directly presses the insert into the pre-drilled hole of the molded plastic, relying on interference fit for fixation. Although its connection strength is slightly lower, it requires no heating equipment, making it suitable for small-batch production or on-site maintenance. This convenient process is commonly used for repairing plastic casings in the home appliance industry.
Insert nuts significantly enhance the load-bearing capacity of plastic parts. Ordinary plastic threads are prone to stripping, but after embedding metal inserts, the parts can withstand several times the tensile force. For instance, the adjustment knobs of medical devices maintain precise positioning even after hundreds of thousands of rotations.
They exhibit exceptional material adaptability: materials such as brass, stainless steel, and aluminum can meet the needs of different environments. 316 stainless steel inserts are used in coastal equipment for salt spray corrosion resistance, while aluminum alloy inserts are applied in aerospace components to reduce weight—achieving a perfect balance between functionality and environment.
The flexibility of installation processes reduces constraints on product design: in-mold injection allows for more complex plastic structures, ultrasonic installation is suitable for precision parts, and cold-press technology simplifies maintenance procedures—providing engineers with more design possibilities.
Through scientific design and precise craftsmanship, these small components perfectly combine the lightweight advantage of plastic with the high-strength characteristic of metal, becoming a key element for improving product quality in modern manufacturing. With innovations in materials and processes, insert nuts will demonstrate connection value in more high-end fields.
