Home > Inserts for Manufacturers > Helical Wire Inserts

Inch & Metric Helical Inserts

What are Helical Inserts, AKA HeliCoil® Inserts?

Helical inserts, commonly referred to by their trademarked name HeliCoil®, are precision-engineered fasteners (coils of wire) designed to provide precise and durable internal threads (female threads) for male threaded fasteners in materials that may be too soft or prone to wear. These inserts are available in inch, mil-spec, and metric sizes and are also commonly referred to in the industry as helical coil inserts, helical wire inserts, helical threaded inserts, or screw thread inserts (STI).

*HeliCoil® is the registered trademark of Stanley Engineered Fastening, recently acquired by Bollhoff.

Widely used in industries such as industrial manufacturing, aerospace, automotive, and electronics, these threaded inserts ensure the reliability and longevity of threaded connections, making them essential components for both repair applications and new installations.

Four typical applications for using Helical wire inserts are: 1) to repair damaged threads in parts that would otherwise have to be scrapped; 2) to strengthen threads against failures due to stripping, seizing or corrosion; 3) to convert threads between inch and metric sizes 4) to create new threads in soft materials such as aluminum, magnesium, or plastic. The wire coil design of these threaded inserts allows them to expand and contract slightly under load, providing a secure threaded connection.

Helical Inserts at MF Supply

Choose from the Inch & Mil-Spec or Metric Helical Inserts product categories below to see available sizes and materials

MF Supply is a leading supplier with expertise in helical inserts. We also supply the full family of threaded inserts, including Keensert® style key-locking inserts, nutserts and rivnuts. We stock and source a large inventory, including major brands and equivalents to HeliCoil®, Recoil®, KATO®, E-Z Lok, PowerCoil, Bollhoff, Perma-Coil, V-Coil and Time-Sert and more—in imperial, metric and mil-spec sizes and materials.

In addition to major brands and equivalents, our catalog of imperial, metric, and mil-spec helical inserts includes many styles, sizes and materials. We’ve detailed the main available helical insert styles below.

Helical Insert Styles Available – Tang &Tangless

Helical wire inserts come in 2 main styles: tanged and tangless (currently, MF Supply specializes in the tanged style).

The original and widely used tang style has a prong at one end to facilitate installation. The newer tangless style has no prongs to break off, retrieve, or lose. Tangless inserts are commonly used in electronic applications where loose tangs might cause damage.

Helical wire inserts can be free-running or self-locking.

Free running is the most common style used for thread repair. The “free” diameter of the insert is larger than the installed diameter and this configuration generates balanced pressure distribution between the coils and threads.

Self-locking style inserts are recommended for applications that require constant torque or are subject to stress or vibration. The locking style features a crimped turn that acts as a locking mechanism that grips the bolt or screw to prevent loosening from vibration, eliminating the need for lock wiring, locknuts (lock nuts), lock washers, pellets/patches or other thread locking devices.

Internal Diameters available include American/inch #2-56 to 1 ½-6” and metric M2 to M36. Standard inserts’ lengths measure from 1x to 3x the diameter. Note: larger sizes may be available by special order.

Free-Running Coarse Thread (UNC) Helical Inserts (Tanged)

Free running coarse thread helical inserts, often available in series MS122076 through MS122275, MS21208, NAS1130, MS33537, NA0276 and MA3279 offer a smooth and reliable thread. Made from high-quality 18-8 stainless steel, these inserts are perfect for general-purpose applications, providing durable and wear-resistant threads. Stock sizes include 1/8 through 1 1/2-6 for imperial & mil-spec, and M2.2 x 0.45 through M27 x 3 for metric.

Self-Locking Coarse Thread (UNC) Helical Inserts (Tanged)

For applications requiring added security, self-locking coarse thread helical inserts, such as series MS21209-C, NAS1130, MS33537, NA0276 and MA3329 feature an integrated locking mechanism. These stainless-steel inserts reduce loosening under vibration and dynamic loads, ensuring a secure and stable connection. Stock sizes include 1/8 through 1 1/2-6 for imperial & mil-spec, and M2.2 x 0.45 through M24 x 3 for metric.

Free Running Fine Thread (UNF) Helical Inserts (Tanged)

Free running fine thread helical inserts, including series MS124651 through MS124850, MS21208, NAS1130, MS33537, NA0276 and MA3279 are made to fine thread (UNF) specifications, often used for precision applications that demand tighter thread tolerances. Also crafted from 18-8 stainless steel, these threaded inserts deliver reliable and consistent performance in high-precision environments. Stock sizes include 3-56 through 1 1/2-12 for imperial & mil-spec, and M8 x 1 through M36 x 3 for metric.

Self-Locking Fine Thread (UNF) Helical Inserts (Tanged)

Combining the benefits of fine threading with a self-locking feature, self-locking fine thread helical inserts, especially from series MS21209-F, NAS1130, MS33537, NA0276 and MA3329 provide exceptional fastening security. These inserts are ideal for applications where the fine threads, vibration resistance, and secure fastening are critical. Stock sizes include 3-56 through 1 1/2-12 for imperial & mil-spec, and M10 x 1.25 through M24 x 2 for metric.

Helical Insert Materials Available

Helical inserts are manufactured in 18-8 and 316 stainless steel, Inconel X-750, Nitronic 60 & 90, and Phosphorous Bronze. Not all materials are available off-the-shelf in all sizes. 18-8 Stainless steel is the standard stocked material for most sizes and configurations. Below we break down the attributes and uses of each material. Helical inserts, commonly used for reinforcing or repairing threaded holes, are typically made from the following materials:

  1. Stainless Steel 18-8: The most common and standard material for helical inserts, this type of stainless steel provides a balance of good corrosion resistance and strength. It's a common choice for applications where both durability and corrosion resistance are required, making it suitable for general use in a variety of environments.
  2. Stainless Steel 316: This grade of stainless steel is often chosen for its excellent resistance to corrosion, particularly in harsh environments, making it suitable for applications in marine, chemical, and food processing industries. are suitable for both repairing and creating secure, reliable threads in a wide range of materials.
  3. Inconel X-750: This is a nickel-chromium alloy used for its corrosion and oxidation resistance as well as its high strength at temperatures up to 1300°F (700°C). Inconel Helicoil inserts are ideal for applications in aerospace and other high-temperature environments.
  4. Phosphor Bronze: Used primarily for electrical applications, phosphor bronze inserts offer good conductivity and corrosion resistance, along with a lower strength compared to stainless steel or Inconel.
  5. Nitronic 60: A higher-grade stainless steel, Nitronic 60 is known for its wear resistance and anti-galling properties, making it suitable for applications where high friction is expected.

These materials are chosen based on their mechanical properties, corrosion resistance, and specific application requirements, ensuring that the insert performs well under the expected service conditions.

Note: Additional materials may be available upon request. Send us an RFQ and we can help you find the helical insert that you’re looking for!

What are the Features & Benefits of Helical Inserts?

Helical inserts provide secure, reliable, and durable threads in weaker parent materials. They may be used to repair a stripped threaded hole, provide a durable threaded hole in a soft material, place a thread on a material too thin to accept it, mold or cast threads into a work piece thereby eliminating a machining operation, or simplify changeover from unified to metric threads or vice versa. They also offer high reliability, versatility, and an easy installation process. Here are some of the top features and benefits of these versatile threaded inserts.

  1. Repair rather than scrap parts – Wire inserts remain the most cost effective, efficient and fastest method to repair damaged threads.
  2. Stronger Assemblies – The flexibility of the insert provides a more balanced load distribution, practically eliminating thread erosion and providing better stress allocation, even in low strength materials.
  3. Wear and Corrosion Resistance – Thread life is increased as thread friction is virtually eliminated, which becomes valuable in applications requiring repeated assembly and disassembly. Surface coatings are available for applications involving severe corrosive and extreme temperature conditions.
  4. Minimize space and weight – Lighter and less expensive than other thread inserts, these wiry fellows can be incorporated into existing designs, often allowing the use of thinner or lighter parent materials.
  5. Convert threads from Metric/Inch – Rather than replace all your hardware, taps and dies, you can use Wire inserts to convert threads and use your existing hardware and tools.

Helical Insert Installation Steps

  1. Drill the Hole: Use a correctly sized drill bit to drill a hole where the helical insert will be installed. Ensure the hole is clean and free of debris.
  2. Tap the Hole: Use a matching tap to create threads in the drilled hole. This step is crucial as it forms the base threads that will hold the helical inserts in place. Ensure that the tapped threads are clean and free from any chips or debris.
  3. Insert the Helical Insert:
    • the helical insert onto the installation tool. Align the tang of the insert with the notch on the installation tool.
    • the insert into the tapped hole using the installation tool, applying even pressure. Ensure the insert goes in smoothly and is not cross-threaded.
  4. Set the Insert: Continue threading the insert until it is flush with or slightly below the surface of the material.
  5. Break the Tang: Use a tang break-off tool or a punch to remove the tang at the bottom of the insert. Place the tool into the insert and give it a sharp tap to break the tang off cleanly. This step ensures that the hole remains open and usable for the bolt or screw.


Cross-reference tables' links:

Resources:

Why Buy Helical Inserts from MF Supply?

With over 50 years of experience as a supply chain partner to manufacturers, and deep and broad expertise in fasteners and inserts, MF Supply can help with all your fastening and hardware needs.

MF Supply stocks and sources a large inventory of helical insert (AKA HeliCoil insert) options including Free Running Coarse Thread (UNC), Self-Locking Coarse Thread (UNC), Free Running Fine Thread (UNF), and Self-Locking Fine Thread (UNF) helical inserts in stainless steel, and in inch/imperial, mil-spec and metric sizes. Our mil-spec and certified insert products are DFAR compliant with the manufacturers’ Certificate of Conformance, and full physical chemical certifications available upon request.

Can't find what you're looking for? Email us at [email protected] for a custom quote. "We have the right screw for you" is our motto after all!