What the heck is a Keensert® Key-locking insert?

 

 

What the heck is a Keensert® Key-locking insert?

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  Key-locking insert 

 

We close out the first quarter of 2013 by introducing you to the Keensert Key-locking insert. Like its relative, the Helical wire insert, (see January 2013), the Key-locking insert was originally designed to repair parts with damaged threads.

What is a Keensert Key-locking insert?

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. Keensert® is the registered trademark for one of the most popular brand names for this part and is used commonly to describe this insert.

Who uses Key-locking inserts?

Generally, Key-locking inserts are used to distribute loads and strengthen or repair 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.

Typical applications are transmission housings, electronic equipment and suspension units. Key-locking inserts are common in the aerospace industry.

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

There are three main differences between Key-locking inserts and Helical Wire Inserts: Key-locking inserts are stronger than helical wire inserts, they are easier to install than helicals, and they are more expensive!

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. 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.

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.

What styles are available?

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

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.

General-purpose 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.

Installation is 5 easy steps!

1) Drill with a standard tap drill and countersink with a standard 82° – 100° countersink (90° for Miniature Inserts). Note: Drill is oversize see charts for proper dimensions.

2) Tap new threads with a standard tap.

3) Screw in the insert until it is .010-.030 (.005-.015 for Miniature Inserts) below the surface. Keys locate the proper depth.

4) Drive keys down with several hammer taps on the proper installation tool.

5) You are done!  

 

Considerations for selecting and using Key-locking inserts.

  • Inserts often show up under their Mil-spec numbers, which can be crossed to commercial equivalents. Some common Mil-spec series for Key-locking inserts include: MS5180, MS51831, MS51832, NAS1394, NAS1395, NA0146, NA0147, NA0148, NA0149, NA150, NA0151.
  • As discussed, Key-locking inserts are often referred to by their brand names, which can often be substituted by generic equivalents. Popular brands include: Alcoa, Fairchild, Keensert and Tridair.
  • Materials available include Carbon steel, Stainless Steel, Alloy 4140 and A286.
  • Diameters available: American – #6   to   1 1/2 ” and Metric – M4   to   M24
Key-locking inserts at MF SupplyWe offer:  

  • The full range of commercial and mil-spec parts
  • Products kits including single and multiple sizes
  • We are authorized distributors for Chrislynn and E-Z Lok

For more detailed information on Key-locking insert, visit us at http://www.mfsupply.com/Keensert_Style_Inserts_s/1864.htm

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


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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