Heat Set Inserts for 3D Printers and Injection Molded Parts Brass Threaded Knurled Nuts

Description

What Are Heat Set Inserts?

Heat Set Inserts (also called thermal inserts or heat-staked threaded inserts) are specialized metal fasteners designed to be permanently installed into thermoplastic parts using heat. When heated, the surrounding plastic melts and flows around the insert’s knurled or flanged exterior, creating a strong, vibration-resistant threaded connection upon cooling. This process is ideal for creating durable threads in plastics where mechanical fastening would fail.

Specifications of Heat Set Inserts

1. Material

• Brass (most common, excellent thermal conductivity for even heating).

• Stainless Steel (for corrosion resistance in harsh environments).

• Aluminum (lightweight applications with lower load requirements).

2. Surface Treatment

• Nickel Plating (improves corrosion resistance and solderability).

• Zinc Plating (basic corrosion protection for brass inserts).

• Passivated Stainless Steel (enhanced corrosion resistance).

3. Common Specifications

• Thread Sizes: M2–M12 (metric), #2–1/2″ (UNC/UNF).

• Design Features:

  • Knurled Exterior (improves plastic adhesion).

  • Flange/Shoulder Options (for load distribution).

  • Internal Thread Types (standard, micro, or self-tapping).

• Installation Temperature: Typically 200–300°C (varies by plastic type).

4. Applications

• Consumer Electronics (plastic housings for screws in laptops, phones).

• Automobile (interior trim panels, sensor mounts).

• Medical Devices (disposable plastic equipment with sterile threads).

• Industrial Equipment (plastic covers, enclosures).

• 3D Printed Parts (reinforcing threaded holes in printed prototypes).

Excellent Case: Drone Motor Mount in 3D-Printed Frame

Challenge

A drone manufacturer needed to secure brushless motors to a 3D-printed nylon frame without compromising the lightweight structure. Traditional screws stripped the plastic threads after repeated vibration, causing motor misalignment and crashes.

Solution

• Heat Set Inserts (Brass, M3, Knurled) were installed into the nylon motor mounts.

• Installation Process:

  1. A precision hole was drilled in the 3D-printed part.

  2. A soldering iron with a heat-set tip (250°C) was used to press the insert into the plastic.

  3. The nylon melted and flowed around the knurling, forming a permanent bond upon cooling.

  4. Motors were secured with high-strength titanium screws.

Results

✔ Zero Thread Stripping – Withstood 50+ hours of high-frequency vibration.
✔ Weight Savings – Eliminated the need for metal reinforcement plates.
✔ Field-Replaceable – Motors could be unscrewed/replaced without damaging the frame.

Industry

UAV/Drone Manufacturing (High-Performance Quadcopters)

Why Use Heat Set Inserts?

✅ Vibration-Resistant Threads – Superior to tapped plastic or self-tapping screws.
✅ Lightweight – No need for bulky metal nuts/plates.
✅ Chemical Bonding – Plastic re-solidifies around the insert for maximum hold.
✅ Compatible with 3D Printing – Perfect for reinforcing printed threads.