Inserts for plastics are engineered components designed to provide strong, durable, reusable threads inside both thermoplastic and thermoset parts. With the increasing use of plastics in engineering, inserts for plastics help ensure reliability, performance, and cost efficiency. Choosing the right insert depends on plastic type, part geometry, load requirements, and production method.
PRODUCT INDEX
PRODUCT SELECTION GUIDE
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KEY SELECTION CRITERIA
When selecting inserts for plastics, consider the following:
- Type of plastic: Thermoplastic vs thermoset, hardness, and sensitivity to stress.
- Load types: Pull-out strength, torque-out resistance, and jack-out load.
- Boss geometry and wall thickness: Sufficient plastic around the insert to provide proper support.
- Hole design and tolerances: Tapered vs straight, moulded vs drilled, and correct chamfering.
- Installation method: Press-in, heat-staking, mould-in, or tapping, depending on the application and production volume.
Popular Insert Types & Features
| Insert Type | Best Use / Key Advantages |
|---|
| Tech-Sonic | High torque and pull-out resistance with opposed knurls and vanes; suited for medium and hard thermoplastics. |
| Sonic-Lok | Quick installation by heat or ultrasonic methods; ideal for speed and strength in thermoplastics. |
| Taper-X | Designed for tapered holes with angled splines for higher torque and pull-out performance. |
| Mini-Tech | Miniature insert for small applications; allows use of small screws with reduced risk of thread damage. |
| Heat-Lok | Suitable for notch-sensitive plastics; smooth knurls reduce stress concentration. |
| Press-Lok / Fin-Lok / Spiro | Optimized for easy press-in installation or for brittle and thermoset plastics. |
| Screw-Sert | Self-tapping insert for post-mould installation, good for plastics with lower core strength. |
| Mould-Form | Installed during moulding for a flush finish and high performance, ideal for high-volume production. |
When & How to Use Inserts
Ideal applications include:
Plastic parts that need repeatable assembly and disassembly
Components exposed to vibration, thermal cycling, or torque loads
Projects demanding high-integrity threads such as in automotive and electrical enclosures
Key considerations:
Inserts add cost and extra process steps
Over-tightening screws may damage the plastic or cause stress cracks
Thin walls or poor boss geometry reduce performance and reliability
Best practices:
- Test inserts for plastics early during prototyping to confirm performance.
- Specify holes with the correct tolerances and chamfers.
- Select the right installation method for the material and production scale.
- Ensure boss design supports loads without distortion.
- Use engineering support and data to match inserts for plastics to the intended application.