Keensert® Buyer’s Guide

Keensert® Buyer’s Guide

5 Things You Need to Know

If you are a precision manufacturer working in high-torque and high-temperature situations, you might already be familiar with Keensert® key-locking inserts.  Common uses include thread repair applications or to provide thread durability in situations such as aerospace assemblies, electronic equipment and suspension units.

But, what exactly are they and what should you know before buying them? We’d like to help you out with this quick buyer’s guide.

  1. What is a Keensert®?

A Keensert® is a solid bushing style insert that is threaded on both the inside and the outside, and has wedges or “keys” attached at the top. They are generically called key-locking inserts, and are used to distribute loads and repair or strengthen threads against failures due to stripping, seizing or corrosion.

Although the name Keensert® is often used generically (like Band-Aid® or Kleenex®), Keensert®  is the registered trademark of Huck Patents (its close cousin, the Keysert® is a registered trademark of Alcoa Fastening Systems.).

Before you shop, check to see if the bill of materials specifically calls out Huck or Alcoa brand as the Keensert®  manufacturer. If no specific manufacturer’s name is listed, then you can typically use an alternative like Rock Solid brand, a generic equivalent or cross to a MIL-SPEC part.  This becomes important due to price and availability of the brand name parts.

  1. What materials and sizes are available?

Keenserts are available off the shelf in 303 stainless steel or carbon steel. Standard diameters are: American #6-32 to 1 ½” and Metric  M4 to M24. Other diameters (starting at 2-56 and M2) and materials (including 316 stainless steel, and alloys 4140 and A286) are available for special order and usually involve a lead time.

  1. What information do I need for ordering?

To order, you’ll need the manufacturer’s part number or the internal and external thread and material. Alternatively, key-locking inserts often show up under their MIL-SPEC numbers, which can often be crossed to commercial equivalents. Common MIL-SPEC numbers include: MS51830, MS51831, MS51832, NAS1394, NAS1395, NA0146, NA0147, NA0148, NA0149, NA150, and NA0151.

  1. Do I need to buy special installation tools?

When purchasing key-locking inserts, check with your production department to make sure you have the tools you need to properly install inserts. You can buy kits that include a tap, drill, and installation tool.

  1. What level of certification is required?

Generally, a Certificate of Conformance or a COC is sufficient. Full certification with material certs and test reports are often available for a fee.

In summary, in order to have the most efficient Keensert shopping/buying experience, be prepared with the following information before you shop:  Do you need the Alcoa or Huck brand product or can you use a generic or MIL-SPEC alternative?  Make sure to have the manufacturer’s part number, MIL-SPEC part number or the internal/external thread and material.  Do you need an installation tool? Finally, check to see if you require a standard COC or full certs.

For more information about MF Supply contact:

Robin Lieberman, President