What is the Difference Between a Keensert and a Helical Insert?

What is a Helical Inset?

A Helical wire insert is a spring-like precision form wire coil that provides a permanent thread that’s stronger than the parent material. They are also often called a screw thread insert or a Helical insert, but the popular brand name is Heli-Coil, a registered trademark of Emhart Teknologies.

What is a KeyLocking Insert?

A key-locking insert is a solid bushing style insert that is threaded on the inside and the outside with keys on the top. It’s commonly called a Keensert or Keysert, and these are the registered trademark names of Huck Patents and Alcoa Fastening Systems.

Why Would I Use a Helical Insert vs. a Keensert, and Vice Versa?

  • Strength: A key-locking insert is much stronger than a helical insert, particularly in high temperature and high torque environments.
  • Ease of Install: A key-locking insert is easier to install than a helical wire insert.
  • Price: A wire insert is much less expensive than a key-locking insert.

When Would I Use a Keensert?

In a heavy-ware, high vibration, high heat situation when you don’t need to save space and the whole depth is not a key consideration. The key-locking insert is the way to go.

When Would I Use a Helical Insert?

If you need to reduce costs, you’re minimizing space. The Helical wire insert is the way to go. They’re very useful for creating a permanent, strong thread and softer material like aluminum or titanium. And they’re best suited to the lower heat environments.

Learn more about the difference between key-locking inserts and helical wire inserts here!

Learn More About Keenserts vs. Helical Inserts

If you are interested in learning more about our Keensert and Helical Insert product offerings, contact us today! If you’re ready to place your order, check out our products here!


What the heck is a Wire Insert?

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Today, we will introduce you to the Wire insert which was originally designed to repair parts with damaged threads, but has evolved for use in a variety of applications that save time and money and improve product reliability.  Do we have your attention?  Great, then read on…

What is a Wire Insert?

Wire inserts are precision-formed continuous wire coils that provide permanent, wear-resistant threads which exceed the strength of the parent material. Often underestimated, the popular misconception is that Wire inserts are intended solely for thread repair, when, in fact, they have other significant uses discussed in the next section. Not to be confused with other types of solid inserts or rivnuts, Wire inserts resemble springs and are sometimes referred to as “helicals”.

Who uses Wire Inserts?

Wire inserts are used for 3 main reasons: 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. We told you they were versatile!

What styles are available? 

Wire inserts come in 2 main styles: tang and tangless.

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

Wire Inserts can be free-running or 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.

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, lock-nuts, lockwashers, pellets/patches or other thread locking devices.

A third commonly used insert that deserves an honorable mention is a K-type Insert. Sometimes called by the brand Keensert, these externally threaded solid style inserts can be used in almost any material: aluminum, magnesium, cast iron, carbon steel, stainless steel and plastic. K-type inserts have locking “keys” that provide a mechanical lock, and are commonly used in heavy wear and high vibration situations.

5 Features & Benefits of Wire 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.

Lesson Learned, considerations when selecting and using Wire Inserts

  • Inserts are easy to install!   You can use standard drill bits and plug taps to drill and tap the hole.
  • For high volume installations, consider strip feed inserts or use  automatic or air-driven installation tools.
  • Inserts often show up under their Mil-spec numbers, which can be crossed to commercial equivalents. Some common Mil-spec series include MS122076 thru MS122275, NAS1130, MS124651 thru 124850, MS21208, MS21209, MS122076, MS33537, MA3279, MA3329, NA0276.
  • Wire inserts are sometimes referred to by their brand names, which can often be substituted by generic equivalents. Popular brands include: Helicoil, Kato, Keensert and EZ Lok.
  • Materials available include 18-8 stainless steel, phosphor bronze, X 750 Inconel, 316 Stainless steel and inserts may be lubricated or dry filmed to offer easy threading and corrosion protection.
Wire Inserts Available at MF Supply

Here at MF Supply, we supply some of the most common and unusual Wire inserts, including:

  • The full range of commercial and mil-spec parts
  • Products kits including single and multiple sizes
  • Specials including Giant metric, 8-pitch kits, left hand kits and special lengths and diameters
  • We are authorized distributors for Chrislynn and E-Z Lok

For more detailed information on Wire inserts, visit us at http://www.mfsupply.com/SearchResults.asp?Cat=1821

And if you don’t see it listed, as always, ask us. Finding the right screw for you is our tag line after all!

About MF Supply
For over 35 years, MF Supply has been a trusted supplier of Fasteners and Electronic Hardware to OEMs, machine shops, manufacturers, and assemblers of machines and instruments in New Jersey, the greater NYC Metropolitan area and beyond.   We are wholesale only.

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