Plastic Thread Inserts: The Secret Weapon for Giving Plastic Parts Metal-Grade Strength

The “Three Magic Weapons” of Thread Inserts

1. Material Revolution: Combining Lightweight and Strength
   Aluminum Alloy Inserts: 2024-grade aerospace aluminum inserts have 40% higher strength than brass and only 1/3 of its weight. For example, a certain drone motor bracket switched to aluminum inserts, reducing the weight of each piece by 12 grams and increasing the battery life by 8 minutes.
   Stainless Steel Anti-Corrosion: 316L medical-grade stainless steel inserts maintain 92% of the initial thread strength after soaking in disinfectant for 1,000 hours.
2. Structural Design: Making Screws Hold Tighter
   Spiral Knurling Technology: The outer surface of the insert has 45° spiral knurling, increasing the pull-out resistance by 4 times. Tests show that M6 inserts in ABS plastic can withstand an axial tension of 800N, equivalent to lifting an 80-kilogram weight.
   Barb Locking Structure: The tail of the insert is designed with 0.3mm barbs. During injection molding, plastic flows into the barb gap to form a mechanical interlock, and the torsional moment resistance reaches 25N·m, which is 3 times higher than that of ordinary self-tapping screws.
3. Process Innovation: Completing Implantation in 20 Seconds
   Ultrasonic Installation: Generate local heat through 20kHz high-frequency vibration and melt the insert into the plastic within 5 seconds. The installation efficiency is 70% higher than the traditional hot melt process.
   In-Mold Injection Molding Integration: Pre-embed inserts in the injection mold to achieve seamless combination of “metal – plastic” in one molding. A certain automotive lamp shade enterprise uses this process to upgrade the waterproof level from IP54 to IP68.

Real Scenarios: These Industries Are Loving It

1. Consumer Electronics: Say Goodbye to Cracked Screw Holes
   A certain smartwatch brand embeds M2 stainless steel inserts in the watch case, increasing the screw disassembly life from 50 times to 500 times and reducing after-sales maintenance costs by 40%.
   The charging compartment of TWS headphones adopts a “one insert double thread” design, simultaneously fixing the charging contacts and the cabin cover hinge, saving 30% of the structural space.
2. Automotive Manufacturing: The Anchor in Vibrating Environments
   The handle of Tesla’s charging gun is built-in with M8 aluminum inserts. In the temperature difference test from -40°C to 120°C, the thread connection strength fluctuation rate is < 3%.
   The battery pack bracket of new energy vehicles adopts the “insert array” design. 128 connection points simultaneously withstand an impact force of 1,500kg without loosening.
3. Medical Devices: The Last Line of Defense for Safety
   The handle of the endoscope uses titanium alloy inserts. After undergoing 2,000 high-temperature and high-pressure sterilizations, the thread accuracy still remains within ±0.02mm.
   The infusion interface of the insulin pump adopts an insert with a sealing ring, reducing the leakage rate from 0.5% to 0.01%.

1. Material Matching Principle
   For ordinary ABS/PP plastics: Choose aluminum alloy or brass inserts, and control the cost at 0.5 – 2 yuan each.
   For high-temperature nylon/PC materials: Stainless steel inserts must be used, with a temperature resistance of > 150°C.
2. Key Parameter Comparison Table
3. Three Elements for Supplier Screening
   Look at Certification: The automotive industry requires IATF 16949, and the medical industry requires ISO 13485.
   Test the Limit: Request for the cycle test report of -40°C freezing + 120°C baking.
   Verify the Service: High-quality suppliers provide full-process support such as “thread design – insert selection – process verification”. For example, a certain Hangzhou enterprise reduces the customer’s product defect rate from 8% to 0.3% through collaborative development.