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!

Buyer’s Guide to KN95 Respirator Masks: 7 Things to know

KN95 GB2626-2006

Today we introduce our newest product, the KN95 Respirator Mask to the Chinese standard GB2626-2006. Introduced in the US market in response to the Corona virus pandemic and approved for use under the CDC’s EAU, the KN95 is currently being used for protection against Covid-19.

1. What is a KN95 respirator mask?

Regulated by the Chinese government (CE), a KN95 respirator mask is a type of Filtering Facepiece Respirator (FFR).  Similar in function to the USA N95s, KN95s have a minimum of 95% filtration and a maximum 8% leakage to the inside and are made to the GB2626-2006 standard.

2. Who uses KN95 respirator masks?

Mainly used in construction, agriculture, and by healthcare professionals against airborne particles, infectious agents and viruses, KN95s prevent the wearer from inhaling aerosols (dust, smoke, mist) as well as vapors or gases (disinfectants, anesthetic gases, droplets) that are health hazards. KN95s are currently used for protection against the coronavirus.

Interesting fact: Prior to Covid-19, there were ample USA N95s available in the marketplace and KN95s and other country’s FFPs were not widely available in the US.

3. What is the difference between the N95, the KN95 and other FFPs?

N95s, KN95s & other FFPs are all respirator masks that are subject to various regulatory standards around the world. Respirators certified to these standards are expected to have similar performance. There are slight differences in their specifications, like a variation in the maximum pressure the masks must be able to withstand as a person inhales and exhales. Here are the global standards by country:

  • N95 (United States NIOSH-42CFR84)
  • FFP2 (Europe EN 149-2001)
  • KN95 (China GB2626-2006)
  • P2 (Australia/New Zealand AS/NZA 1716:2012)
  • Korea 1st class (Korea KMOEL – 2017-64)
  • DS (Japan JMHLW-Notification 214, 2018)

4. What is the Emergency Authorization Use (EAU) for respirator masks, including KN95 (China GB2626-2006)?

On March 24, 2020, the FDA issued an Emergency Use Authorization (EUA) for importing non-NIOSH approved N95 equivalent respirators from Australia, Brazil, Europe, Japan, Korea, and Mexico who have similar standards to NIOSH. On April 3, 2020, in response to continued respirator shortages, the FDA approved the EAU for Chinese KN95s. KN95s are almost identical in performance to N95 masks. The CDC lists KN95 masks as a suitable alternative when N95s are not available. The FDA says KN95 masks are eligible for authorization if they meet certain criteria, including documentation that they are authentic.

5. Are KN95 and other respirator masks reusable?

Although KN95 respirator masks are meant for single use, the CDC offers guidance on reuse and cleaning of FFPs here: Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare – cdc.gov

6. How do I know my mask is authentic & not counterfit?

Make sure to purchase any Personal Protective Equipment from a reliable supplier who has experience supplying certified and compliant parts.  A reliable supplier will be able to provide you with authentic CE & FDA certifications and should be able to show you how to check that the manufacturer is registered with the FDA. Upon request, a supplier should provide you with a certificate of conformance stating the product has been checked and conforms to the KN95 GB2626-206 standard.

7. What is the price range of the KN95 respirator mask?

KN95s have a wide price range based on quantity, availability and level of certification available. Today, demand far outweighs current supply of FFPs. Beyond the economics of supply & demand, the factors that go into the price of a KN95 include material costs, labor, transporation, duties & tariffs. China is the main manufacturer of Personal Protective Equipment, and since the Covid-19 outbreak, flights from China to the US are limited, inflating the freight costs. In addition, the special nonwoven filtering fabric used in KN95s has also become an in demand commodity. All these factors have led to increased costs. Over time, as supply meets demands, and flights fly more frequently, we expect prices to decrease.

Stay tuned for our next blog, where we discuss our expanded PPE offering, including gloves, hand sanitizer, 3 Ply masks and other PPE.

We Invite You To Request a Quote, Download a Guide or a Line Card Today!

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  2. Same day drop ship from factory for thousands of items.
  3. Functional Equivalents to expensive brand name fasteners save money and reduce long lead times.
  4. Creatively solve problems including hard to find parts and long lead times
  5. WBE/WOSB Woman Owned Certified Small Business.
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“Heli-coils” vs. “Keenserts”: 3 differences you must know-Part 1 of 2

Today we will compare 2 popular fastener products that are used to repair damaged threads or strengthen a weaker parent material like aluminum: Helical Wire Inserts and Key-locking Inserts.  Both are commonly used in precision manufacturing and aerospace applications.

What are the main uses of these threaded inserts?

Both “Heli-coil” or Helical wire inserts and “Keensert” or Key-locking inserts fall under the “Threaded Insert” category of fasteners. A threaded insert, also known as a threaded bushing, is a fastener element that is inserted into an object to add a threaded hole. 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. Although Helical Wire inserts and Key-locking externally threaded inserts are used in similar ways, there are 3 main distinctions that we detail below. But first, let’s take a closer look at each of these fasteners:

What is a Helical Insert Wire Insert? (aka Heli-coil)

Helical 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 Helical wire inserts are intended solely for thread repair, when, in fact, they have other significant uses.  Not to be confused with other types of threaded inserts or rivnuts, Helical wire inserts resemble springs and are sometimes referred to as “Screw Thread Inserts (STI)” ,“Helicals” or by the popular brand “Heli-Coil” which is a registered trademark of Emhart® Teknologies, Inc.

Three 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.

What is a Key-locking insert? (aka Keensert or Keysert)

The Key-locking threaded insert is a solid bushing style insert that is threaded on both the inside and the outside and has wedges or “keys” attached to the top of the insert. These externally threaded inserts are used to distribute loads and repair or strengthen threads against failures due to stripping, seizing or corrosion. Key-locking inserts are commonly used in high torque and high temperature situations, and in applications where fasteners may be repeatedly removed and reassembled. Key-locking inserts are often referred to as Keenserts® and Keyserts, which are registered trademarks for the most popular brand names for this part. (Keensert® is a registered trademark of Huck Patents, Inc. & Keysert® is a registered trademark of Alcoa Fastening Systems).

Typical applications are transmission housings, electronic equipment and suspension units. Key-locking inserts are commonly found in aerospace assemblies.

How do they work?

Helical wire inserts work because the diamond shaped helically formed wire coil screws into a threaded hole to form a mating internal thread for a screw or stud.  

Key-locking inserts are threaded into a pre-tapped hole, and then the keys are hammered into grooves through the threads, permanently locking the insert in place. Their “keys”, which are driven down into the tapped threads, provide a mechanical lock against rotation, especially when the mating stud or bolt will be removed frequently.

What materials, sizes and styles are available?


Key-locking inserts come in four main styles: Miniature, Thin Wall, Heavy Duty Wall (general purpose) and Extra Heavy Duty.

  • Miniature Key-locking inserts are used in electronic and aerospace applications where size and strength are critical. These inserts may be installed in sheet material as thin as 1/16″.
  • Thinwall inserts have smaller external threads than standard heavy-duty inserts and are ideal for tight spaces where less pull-out strength is acceptable.
  • Heavy Duty inserts have a thick, heavy-duty thread wall, suitable for most applications.
  • Extra-heavy duty inserts are used in oversized and overly worn holes.

Key-locking inserts can be internally self-locking or non-locking (the standard is non-locking and is sufficient for the most common applications).

Inserts with the internal self-locking feature are designed to securely lock a bolt when it is entered into the insert only a few turns. Even after repeated installations and removals of the bolt, the lock maintains sufficient locking torque to prevent the bolt from vibrating out.

Common Materials available include Carbon steel, Stainless Steel, Alloy 4140 and A286.

Internal Diameters available: American/Inch #2-56   to   1 ½-6 ” and Metric M2 to M24

Helical wire inserts

Helical wire inserts come in 2 main styles: tanged and tangless (currently, MF Supply spcializes 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 are might cause damage.

Helical 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.

Common Materials available include Stainless Steel, Phosphorous Bronze, Inconel X-750 and Nitronic 60 and 90.

Internal Diameters available: American/Inch #2-56   to   1 ½-6” and and Metric M2   to   M24.  Standard inserts lengths measure from 1x to 3x the diameter. Note: larger sizes may be available by special order.

Why use a Key-locking insert vs. a Helical wire insert?

There are three main differences between Key-locking inserts and Helical wire inserts:

1) Strength: Key-locking inserts are stronger than Helical wire inserts

2) Ease of installation: Key-locking inserts are easier to install than Helical wire inserts

3) Price: Key-locking inserts are more expensive than Helical wire inserts!

So here is some direction on how to select the correct threaded insert for your application:  In heavy wear, high vibration and high heat situations where saving space is not a concern and hole depth is limited, Key-locking inserts are the best bet.

When reducing costs and minimizing space are priorities, Helical wire inserts are the way to go. They are particularly useful for creating permanent strong threads in softer materials such as aluminum, titanium and magnesium alloys, and are best suited to lower heat and lower torque environments.

Stay tuned for our next blog, where we discuss, brands and mil-spec options, how to order and installation options.

We Invite You To Request a Quote, Download a Guide or a Line Card Today!

  1. Full ecommerce enabled website with technical manual available 24/7
  2. Same day drop ship from factory for thousands of items.
  3. Functional Equivalentsto expensive brand name fasteners save money and reduce long lead times.
  4. Creatively solve problems including hard to find parts and long lead times
  5. WBE/WOSB Woman Owned Certified Small Business.
Request A Quote

Please forward you comments to robin@mfsupply.com