Buyer’s Guide to One and done Keensert® Ordering

keenserts installation

Your 5 point checklist to getting it right the first time

What is a Keensert®?

Keenserts® are solid bushing style inserts that are threaded on both the inside and the outside, and have 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. They are commonly used in precision manufacturing and aerospace applications.

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.).

How do I simplify my buying process to get what I need to complete the job on time and right?

We are all familiar with that classic adage “Measure twice, cut once”.  Nowhere is this more relevant than in the world of manufacturing.  If you are involved in procurement, you are challenged with making sure you have the right parts available at the best price  so your factory can deliver on time and on budget.   Missing tools, incorrect paperwork and long delivery times can cause major headaches and negatively impact service levels.

Our goal is to help you make the Keensert buying process easier, which in turn will eliminate stress, reduce multiple shipments and potentially increase your profits.  The result?  Happier customers (and finance departments too)!  So here it goes…..

  1. Make sure to order the correct part.

Due to the price, availability and high minimum order requirements of Huck or Alcoa branded Keensert® parts,  using functional equivalents including Mil-Spec parts has become a common practice.   Request that your supplier makes reference to the part number listed on your bill of materials on their sales order and packing slip. This will ensure you are getting the functional equivalent that you need.

If you are not ordering by part number, make sure to call out both the internal and external thread including the thread class (UNC, UNF, UNJ), the material and plating, and any special finish you need.

  1. Place blanket orders for your total project needs to get the best price and ensure availability of parts when you need them.

Most standard size non-locking miniature and thin wall / light weight Keenserts® are readily available off the shelf in 303 stainless steel or carbon steel.  However, some locking style, nonstandard diameters, 4140 alloy, A286, heavy duty, extra heavy duty, solid and floating style Keenserts® are available only by special order and usually involve a long lead time.  Make sure to get current price and delivery and order parts as early as possible.  Many suppliers allow you to order now and ship later, which can prevent delivery delays.

If you have an ongoing project, calculate your total needs and place your order with staggered delivery dates.  This will get you the best available pricing and ensure you have the parts when you need them.  Remember, price breaks can start at as few as 100 pieces.

  1. Order (the correct) installation tools with Keenserts® for maximum efficiency.

Whereas most common size and material installation tools are readily available off the shelf, less popular sizes and materials might involve a lead time.  Parent materials harder than RC30 or Anondized Aluminum may require that the tapped holes be broached for the keys, which requires the use of broach blades.


broaching tool

In addition, there are manual and power installation tools to choose from, so consult with your supplier on which tool is correct for your job.  Note:  manual tools work well for jobs up to 999 Keenserts®.  For installations of 1000 Keenserts® or more, a pneumatic tool is recommended.

  1. Order the Correct drills and taps for proper installation

Although Keenserts® are installed with standard drills and taps (plus the installation tool and a hammer) each part has a specific hole/tap dimensional recommendation. The drills used are often oversized for the external thread size.  When purchasing key-locking inserts, check with your production department to make sure you have everything you need for proper installation. Note: Drill is oversize see charts for proper dimensions.

Kits are handy to have in the shop and are available for most common sizes.  These kits include 2+ Keenserts®, the associated drill, tap and manual installation tool along with instructions for correct installation.

  1. Request COC, MTRs, DFAR and all required paperwork on your RFQ and PO.

Since using functional equivalents including Mil-Spec parts is a common practice, make sure you have dotted your i’s and crossed your t’s when it comes to paperwork.  Ask your supplier to reference the branded part number listed on your bill of materials on their COC and packing slip to make sure you are getting the functional equivalent that you need.  In most cases, a Certificate of Conformance or a COC referencing the part number you ordered is all the paperwork you need.  Certain aerospace customers need a complete Manufacturer’s Test Report (MTR) package including DFAR statement and passivation certs with full lot traceability.  This might involve a fee, so include it in your RFQ.  Whatever your requirement, include it on your Purchase Order to make sure you have what you need to satisfy your customer’s needs.

In summary, follow this handy 5 point guide when ordering Keenserts® and watch your costs decrease and your service levels soar!

For more information about MF Supply contact:

Robin Lieberman, President

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