Helicals, Free Running & Solid Locking, Metric Sizes
What Are Helical Wire Thread Inserts?
A helical wire thread insert, sometimes known by the trade name Helicoil, is a precision coiled wire insert installed into a drilled and tapped oversize hole to create a strong, wear resistant internal thread. Once installed, the coil's outer diameter engages threads in the parent material while the inner diameter presents a standard internal thread sized to the original fastener, which is useful for repairing stripped or damaged threads or for reinforcing threads in soft materials such as aluminum, cast iron, or plastic.
Free running inserts have a plain, uniform coil profile and are used wherever a standard internal thread is needed. Solid locking inserts include a section of the coil that's deformed to create additional friction against the mating fastener's threads, providing resistance to loosening from vibration without a separate lock washer or thread locker.
Key Features and Benefits
- Reinforces Threads in Soft Materials: distributes load over a wider area than a thread tapped directly into aluminum, cast iron, or plastic.
- Repairs Damaged or Stripped Threads: restores a standard internal thread size in a damaged tapped hole.
- Free Running Option: a plain coil profile for standard, non-locking threaded connections.
- Solid Locking Option: a deformed coil segment adds resistance to loosening from vibration.
- Wide Metric Thread Coverage: sized to standard metric thread diameters and pitches.
Materials and Finishes
- Stainless Steel: corrosion resistant material suited to most general purpose and repair applications.
Standards Compliance
- DIN 8140, Wire thread inserts
- ISO 5855, Wire thread inserts for ISO metric screw threads
Size Range and Availability
Available in a full metric thread size range, sold individually or as insert kits.
Related Categories and Products
Frequently Asked Questions (FAQs)
1. What is a helical wire thread insert used for?
It's used to reinforce internal threads in soft materials or to repair a stripped or damaged tapped hole, restoring a standard internal thread size.
2. What is the difference between free running and solid locking inserts?
A free running insert has a plain coil profile for a standard threaded connection, while a solid locking insert has a deformed coil segment that adds friction against the mating fastener to resist loosening from vibration.
3. Do I need a special tap to install these inserts?
Yes, installation typically requires drilling to the specified oversize diameter and tapping with a matching thread insert tap before installing the coil with an installation tool.
4. What materials benefit most from thread inserts?
Soft or brittle materials such as aluminum, cast iron, magnesium, and plastic benefit most, since a tapped thread alone can strip or wear more easily in these materials.
5. Can a solid locking insert be removed and reinstalled?
It can be removed, but the locking segment's holding force may be reduced after repeated removal and reinstallation of the mating fastener.
6. What sizes are available?
We stock a full metric thread size range, available individually or as insert kits.
