Self Tapping Threaded Inserts Custom Brass Knurled Threaded Repair Insert

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What Are Self Tapping Threaded Inserts?

Self tapping threaded inserts (also called self-threading inserts or screw-in inserts) are fasteners designed to create strong, reusable threads in soft or damaged materials. Unlike standard threaded inserts that require pre-tapping, these inserts have cutting threads or flutes that allow them to tap their own mating threads when screwed into a pre-drilled hole.

They are commonly used to reinforce weak materials (such as plastic, wood, or thin metal) and provide durable, wear-resistant threads for repeated screw assembly and disassembly.

Key Features of Self Tapping Threaded Inserts

1. Materials

Self-tapping inserts are made from various materials to suit different applications:

• Stainless Steel (304, 316) – High corrosion resistance for marine, medical, and outdoor use.

• Carbon Steel (Zinc-Plated, Black Oxide) – Cost-effective and strong for industrial applications.

• Brass – Good electrical conductivity and corrosion resistance for electronics.

• Aluminum – Lightweight and corrosion-resistant for aerospace and automotive.

• Nylon/Plastic – Non-conductive and lightweight for electrical insulation.

2. Surface Finishes & Coatings

To enhance durability and performance, these inserts often have:

• Zinc Plating – Prevents rust in standard environments.

• Nickel Plating – Improves wear resistance and provides a smooth finish.

• Black Oxide – Reduces glare and offers mild corrosion protection.

• Passivation (for Stainless Steel) – Enhances corrosion resistance.

• PTFE (Teflon) Coating – Reduces friction for easier installation.

3. Common Sizes & Specifications

• Thread Sizes: Metric (M2, M3, M4, M5, M6) and Imperial (#4-40, #6-32, #8-32, #10-24).

• Outer Diameter (OD): Varies based on material thickness (typically 3mm–12mm).

• Length: 5mm–20mm (custom lengths available).

• Drive Types: Hex key (Allen), slotted, or external hex for installation.

• Flute Design: Single or multi-flute for better chip removal in plastic/metal.

4. Applications

Self-tapping threaded inserts are widely used in industries where strong, reusable threads are needed in soft or low-density materials:
✔ Motoryzacja – Securing interior panels, sensors, and electrical components in plastic housings.
✔ Elektronika – Reinforcing screw threads in plastic casings (laptops, routers, etc.).
✔ Aerospace – Lightweight fastening in composite materials.
✔ Furniture & Woodworking – Adding durable threads to MDF, plywood, or particleboard.
✔ Medical Devices – Providing secure fastening in plastic surgical equipment.
✔ Industrial Machinery – Repairing stripped threads in soft metals like aluminum.

Excellent Case: Reinforcing Plastic Housing in Electric Vehicle (EV) Battery Systems

Challenge:

An EV battery manufacturer needed a reliable way to secure high-voltage wiring connectors inside plastic battery housings. The problem was:

• Plastic threads wore out quickly due to frequent maintenance checks.

• Standard screws stripped the plastic after a few installations.

• Vibration resistance was critical to prevent loosening.

Solution:

• Stainless Steel Self-Tapping Threaded Inserts (M5, Hex Drive, 10mm Length) were installed into pre-drilled holes in the plastic housing.

  • The self-tapping flutes cut precise threads without cracking the plastic.

  • Stainless steel (316 grade) resisted corrosion from battery chemicals.

  • Hex drive allowed easy installation with a standard Allen wrench.

  • Knurled outer surface improved grip in the plastic to prevent rotation.

Result:

✅ Durable threads survived 50+ assembly/disassembly cycles without wear.
✅ No more stripped screws, reducing maintenance costs.
✅ Vibration-resistant due to the metal-to-plastic locking design.
✅ Faster servicing since technicians could repeatedly remove/reinstall screws without damaging the housing.

Conclusion

Self-tapping threaded inserts are essential for creating strong, long-lasting threads in soft materials. Their versatile materials, coatings, and designs make them ideal for automotive, electronics, aerospace, and industrial applications where durability and reusability matter.

For high-stress environments (like EVs or machinery), these inserts prevent thread failure and extend product lifespan.