Product Overview

Our Brass Threaded Inserts are specifically designed to provide strong, permanent threads in plastic parts. Whether you are working with 3D printed components (PLA, PETG, ABS) or industrial injection molding, these heat-set inserts ensure a rock-solid connection. The opposing diagonal knurl design provides high torque-out and pull-out resistance, making them far superior to standard threaded nuts.

Unlike self-tapping screws that create weak threads in plastic, our threaded inserts for plastics create a metallurgical bond between the brass insert and the surrounding plastic material. This results in connections that can withstand repeated assembly and disassembly without degrading the thread quality, making them the professional choice for demanding plastic assembly applications.

Technical Highlights

Superior Grip: The dual-direction spiral knurling creates a massive surface area that grips the plastic firmly once cooled, preventing spinning or loosening. Our opposing diagonal knurled inserts for high torque applications provide up to 3x greater pull-out resistance compared to straight knurl alternatives, ensuring reliable performance under demanding mechanical loads.

High-Quality Material: CNC machined from high-tensile H59/H62 brass, ensuring excellent thermal conductivity for fast heating and high corrosion resistance. The premium brass material provides superior durability compared to aluminum or steel inserts, making our corrosion resistant brass inserts for electronics ideal for sensitive electronic and medical device applications.

Precision Threads: Clean, burr-free internal threads (M2 to M8) ensure smooth bolt installation every time. Each insert is manufactured to tight tolerances with precision CNC threading, ensuring consistent thread engagement and reliable performance across every production batch.

Versatile Installation: Can be installed via heat (soldering iron or heat press) or ultrasonic equipment into thermoplastic materials. Our ultrasonic inserts are optimized for high-volume production environments where speed and consistency are critical, while heat-set installation is perfect for prototyping and low-volume manufacturing.

Technical Specifications

Ideal Applications

3D Printing Enthusiasts: Perfect for Voron projects, RC cars, and custom enclosures. Our M3 brass heat set inserts for 3D printing provide professional-grade threaded connections in PLA, PETG, ABS, nylon, and other thermoplastic filaments. The heat-set installation method creates a permanent bond that is significantly stronger than self-tapping screws, which can strip or crack printed parts.

Electronics Industry: Essential for securely mounting PCBs within plastic housings. The brass threaded bushing for injection molding provides reliable, electrically conductive grounding points and secure mounting for circuit boards in consumer electronics, industrial control panels, and communication devices.

Automotive: Applied in interior plastic panels, dashboard components, and lightweight structural assemblies. Our threaded inserts for plastics withstand the temperature variations and vibrations of automotive environments, providing reliable fastening points that won’t loosen over time. Ideal for EV battery housings and lightweight plastic components.

Medical Devices: Used for creating durable threaded points in specialized plastic medical equipment. The corrosion resistant brass material meets medical industry requirements for biocompatibility and sterilization resistance, making these inserts suitable for diagnostic equipment housings, surgical instrument handles, and patient care devices.

Industrial & Consumer Goods: Widely used in power tool housings, appliance casings, furniture assembly, and consumer product enclosures. The M2 M4 M5 M6 knurled nuts wholesale program provides comprehensive size coverage for manufacturers across all industries.

Installation Guide

How to Install Heat Set Inserts in 3D Prints: Follow these four steps for a perfect, permanent installation every time. Our step-by-step guide ensures professional results even for first-time users.

Step 1 – Prepare the Hole: Design the hole slightly smaller than the insert’s outer diameter. For M3 inserts (OD ~4.7mm), use a 4.0-4.2mm hole. For M4 inserts (OD ~6.0mm), use a 5.2-5.4mm hole. The correct hole size ensures the plastic flows around the knurls for maximum grip. Refer to our size chart for exact dimensions for each thread size.

Step 2 – Heat Up: Use a soldering iron at approximately 200°C-250°C (depending on material). PLA requires lower temperatures (180-200°C), while ABS and nylon require higher temperatures (220-250°C). Set the soldering iron to the appropriate temperature and allow it to fully heat up before starting. A temperature-controlled soldering iron is recommended for consistent results.

Step 3 – Press In: Place the insert onto the heated soldering iron tip and position it over the hole. Gently press the insert into the hole until it is flush with the surface. Apply steady, even pressure – do not force the insert. The surrounding plastic will soften and flow around the knurls, creating the mechanical bond. Keep the insert perpendicular to the surface during insertion.

Step 4 – Cool Down: Allow the plastic to re-solidify around the knurls for a permanent bond. Hold the insert in place for 10-15 seconds after reaching the desired depth to prevent it from floating back out as the plastic cools. Do not apply force to the insert until the plastic has fully cooled. The complete cooling process typically takes 30-60 seconds.

Ultrasonic Installation (Production): For high-volume manufacturing, ultrasonic insertion provides faster, more consistent results. The ultrasonic horn contacts the insert, and high-frequency vibrations generate heat through friction between the insert and plastic. This melts the plastic around the knurls in 1-2 seconds. Ultrasonic installation requires specialized equipment but offers superior consistency for production runs of 1,000+ units.

Molded-In Installation: For injection molding production, inserts can be placed directly into the mold cavity before plastic injection. The molten plastic flows around the knurls during the molding process, creating an extremely strong bond. This method requires custom mold modifications but provides the highest strength and lowest per-unit cost for large production volumes.

Troubleshooting: If the insert spins after installation, the hole may be too large or the temperature too low. If the plastic melts excessively, reduce temperature or insertion time. If the insert tilts during installation, ensure the soldering iron is held perpendicular to the surface. For complex applications, contact our engineering team for technical support. Learn more about our manufacturing capabilities.