“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?

Keenserts

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


Buyer’s Guide to Self-Clinching Fasteners 2019

SelfClinchNuts_Multiple

MF Supply continues to expand our offering of products available for purchase online. We are thrilled to offer Self-clinching fasteners available from stock that can be purchased on our website or by email, phone or fax. We are an authorized distributor for Captive Fasteners, a US based manufacturer since 1974, with a factory right here in our NJ backyard!

What are Self-clinching fasteners?

Self-clinching fasteners are generally classified as part of the electronic hardware or precision engineered fastener family and are not governed by IFI, ANSI or ASME standards. A self-clinching fastener, also known as press-fit or clinch style captive fastener, is a part that when pressed into a drilled, punched or machined hole, provides an economical method of joining sheet metal panel applications and is well-suited for use in printed circuit boards.

Self-clinching fasteners are used in many industries; both commercial and aerospace.

Self-clinching Fasteners available at MF Supply

MF Supply offers the full catalog of Captive branded fasteners & PEM® equivalents in inch & metric sizes. We have the following parts available for purchase online, in stock and ready to ship from our national distribution centers:

Additional Series available include, but are not limited to, floating, self-locking, blind-hole, flush, and broaching fasteners.

Steel_Standoff_Prod

How do they work? 

Self-clinching fasteners work by displacing the host material around the mounting hole, causing it to cold flow into a specially designed annular recess. Knurls, serrated rings or ribs on the fastener hold them firmly in place. Self-clinching fasteners become an integral permanent part of the panel or frame and eliminate problems associated with loose hardware. Installation requires access to both sides of the panel and self-clinching fasteners may be installed using any parallel acting squeezing force.

What are the advantages of Self-Clinching fasteners?

Self-clinching fasteners provide strong thread in very thin material & offer high push out and torque out resistance. They take less space and require fewer assembly operations than caged or anchor nuts. They can be installed during fabrication or during final assembly and work well in applications when loose hardware wouldn’t be accessible.

Some of the key advantages include:

  • No special hole preparation, such as chamfering and deburring is required.
  • Low installed costs, fewer parts to handle, fewer assembly steps and less assembly time.
  • No retapping necessary after application.

Reverse side of metal sheet remains flush – no swaged rim protrusion.

What are the differences between branded fasteners like PEM & Captive and generic Self-clinching fasteners?

SelfClinchStudSelf-clinching hardware is frequently referred to by the OEM brand name PEM®. Captive Fastener is a USA based manufacturer and offers functional equivalents to PEM® branded self-clinching fasteners.  In addition to PEM® & Captive, there are a variety of manufacturers of self-clinching fasteners available in the marketplace including the major national catalog brands. Functional alternatives will be equivalent in form fit and function and offer similar performance.

To see if using alternative brands or functional equivalents will work for your business, refer to our handy guide.

We have also included a cross reference lookup table for PEM® product types vs. Captive product series below.

What information for I need for ordering? 

The easiest way to order is by manufacturer part number. If you don’t have one, you’ll need to specify fastener type & style, thread diameter & pitch, fastener length, material and plating. For example: a 10-32 X 3/8 Flush Head Self-Clinching Stud Steel Zinc plated can also be ordered as a PEM® FH-032-6, (or a PEM® FH-032-6-ZI as sometimes PEM® calls out the plating) or a Captive CH1032-6.  This part is also offered by a national catalog brand under part number 93580A166.

Additional Series available include, but are not limited to, floating, self-locking, blind-hole, flush, and broaching fasteners.

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 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.

Knurled Thumb Screws Buyer’s Guide

6 Things to Know When Buying Knurled Thumb Screws

 

  1. What is a Knurled Thumb Screw? 

Knurled Thumb Screws are generally classified as part of the electronic hardware or precision fastener family and are not governed by IFI, ANSI or ASME standards. They are solid one piece screws with a cylindrically shaped oversized knurled head, a fully threaded shank construction and a blunt machine screw style end. They are used in applications where periodic manual adjustment is required and finger pressure can supply sufficient tightening torque.

Knurled Thumb Screw

Knurled Thumb Screw with Washer Face

  1. What materials and sizes are available?

Knurled Thumb Screws are readily available off the shelf in type 18-8/303 stainless steel and Aluminum. Some manufacturers stock knurled thumb screws in brass or other materials. Parts are typically supplied without any coating or finish.

Standard stock sizes for the thread diameter are Inch from 4-40 to 1/4-20 with standard lengths up 1” depending upon the manufacturer.

316 stainless steel, alloy and other exotic materials, and special diameters and lengths are available in certain sizes and/or for special order and usually involve a lead time.

  1. What information do I need for ordering?

The easiest way to order is by manufacturer part number. If you don’t have one, you’ll need to specify thread diameter, thread length, head style and material. For example: 6-32 x 3/8″ Knurled Thumb Screws with a Washer Face in Stainless Steel 18-8 is a popular Thumb screw.

Typical head styles are a modified fillister with a flat top where the head diameter is about twice the head height and does not need to be specified. Low head fillisters are available in certain sizes.

  1. What are some of the popular Fastener Brands with Functional Equivalents?

Popular OEM fastener brands include: Amatom, Cambion, Concord, Globe, HH Smith, Keystone, Lyn-tron, Misumi, Pic Design, RAF, and WM Berg. A comprehensive selection of Knurled Thumb Screws is also offered by McMaster-Carr, MSC Industrial and Grainger.

One surefire way to save money and shorten delivery time is to cross the OEM brand part on your bill of materials to a functional equivalent.

Let’s take the above example of a 6-32 x 3/8″ Knurled Thumb Screws with a Washer Face in Stainless Steel 18-8 is a popular Thumb screw.

This part is offered by the Five brands (yes Five!!) listed below under the following part numbers:

  • Grainger 2KB93
  • Lyn-tron SS7603
  • RAF 7103-SS-0
  • Mcmaster-Carr 99607A116
  • Unicorp THS1004-M07-F16

Each manufacturer has a different price point, but the general physical and chemical dimensions make them functional equivalents or Brand alternatives.

  1. Helpful Hints about Categories of Thumb Screws

There are 2 distinct Thumb Screws categories:

1) Knurled Thumb screws, which are covered here, are part of the precision screw family. They are made 2 ways: Washer face/flared collar or plain/shoulderless. They are typically stocked in aluminum and stainless steel. Other options such as narrow, high profile, slotted may also be available in certain sizes.

2) Type A and Type B Spade style thumb screws are part of the Industrial fastener family per ASME B18.6.8, along with Wing screws. Spade style thumb screws may be available in steel and in diameters up to 1/2”.

  1. What level of certification is required?

Generally, a Certificate of Conformance or a COC is sufficient for your customer. Full certification with material certs and test reports are often available for USA-made and Mil-Spec parts for a fee.

Knurled Thumb Screws at MF Supply

We offer:

  • The full range of commercial and Mil-Spec parts, including parts that are DFARS and RoHS compliant.
  • Brand names and generic equivalents.
  • Custom made parts per print in non-standard and exotic materials and finishes.
  • Inch and metric sizes.

For more detailed information about Knurled Thumb Screws, visit our website. And if you don’t see it listed, as always, ask us. “Finding the right screw for you” is our tag line after all!

For more than 40 years, MF Supply has helped American manufacturers streamline operations, saving them time and money with our sourcing expertise and unique supply chain strategies. We are a WBE/WOSB certified stocking distributor of fasteners and electronic components.

We work with the best established factories in the United States and DFARS-certified countries, and stock a huge inventory including all major brands and equivalents. MF Supply provides solutions including: same-day drop ship direct from the factory; custom sizes, materials and plating options; and DFARS parts with full paperwork and Certificates of Conformance.

We creatively solve common problems including hard-to-find parts and long lead times. Our sourcing and reworking expertise includes fast turnaround for modification of existing parts, hard to find standards and specials, special threads, non-standard diameters and lengths, exotic materials, special platings and short runs. We provide functional equivalents to expensive brand name fasteners and help our customers save money while reducing lead times.


Standoffs and Spacers Buyer’s Guide

standoffs and spacers mf supply

7 things you need to know

According to the dictionary, a standoff is defined as “a stalemate or a deadlock between two equally matched opponents and a spacer is a piece of material used to maintain space between 2 things.   In the world of precision manufacturing, standoffs and spacers are mechanical components that are used the create space or join parts together, typically in PC boards.  Below are 7 things to know to have the most efficient buying process.

  1. What are spacers and standoffs?

Often classified as Electronic or Panel Hardware, Standoffs and Spacers are commonly used to mechanically support and electrically connect and position components within assemblies, typically in PC boards and instrument panels.

  1. What’s the difference between a standoff and a spacer?

Both standoffs and spacers have a hex or round shaped body, and 2 openings.  The main difference is that spacers are unthreaded with an inside clearance hole, and standoffs are threaded on both ends.  Threads may be male (external) r female (internal).

  1. Who uses standoffs and spacers?

Look inside an assembled circuit board, and you will be greeted by a bevy of Standoffs and Spacers, because in the world of Electronic Hardware, they are the standard for connecting and mounting circuit boards, panels, doors, and gears. Both are commonly used to properly position parts within an assembly, to reduce component contact, to elevate stacked sections, to ensure enough room for heat to dissipate, and to separate or create space between two objects. These guys are workhorses!

  1. What materials and platings are available?

Common materials include aluminum, brass, plastic/nylon and stainless steel. Common platings include clear anodized, nickel, gold iridite and zinc plated. There are over 20 common platings available! Here is a guide to most common materials:

  • Aluminumis popular because of its ratio of weight to strength. It is light, non-magnetic, performs well in severe temperatures, and has insulating properties.
  • Brassis used in making high-quality standoffs. It is conductive, resists corrosion, and is non-magnetic. It is costlier and heavier than aluminum and is usually plated zinc or nickel.
  • 18-8 Stainless Steelis strong, conductive, nonmagnetic and offers excellent corrosion resistance.
  • Nylon 6/6is superlight, nonconductive, and resistant to chemicals and solvents.

316 stainless steel, alloy and other exotic materials, and special diameters and lengths are available in certain sizes and/or for special order and usually involve a lead time.

  1. What sizes are available off the shelf?

Standard stock sizes run from 3/16 – 1/2 body diameter, 1/4 to 2” long with threads starting at 2-56 running through 1/4-20 and clearance holes ranging from #2 though 1/4”. Metric stock sizes run from M3.5-M6 body diameter with M2.5, M3 and M4 threads.  Remember, the lengths and threads available depend upon the diameter of the body and not all size configurations will be available.

As always, special lengths and sizes are available – just ask!

  1. What information should I provide to get an accurate quote?

The easiest way to order is by manufacturer part number.  If you don’t have one, you’ll need to specify body diameter, body shape (hex or round), body length, thread size & gender (male or female), material and plating.  For example, a popular standoff size is a 1/4 hex x 1/2 Long x 10-32 male Standoff in Stainless Steel.

  1. Are there other factors to consider?

YES! One surefire way to save money and shorten delivery time is to cross the OEM brand part on your bill of materials to a functional equivalent.  Popular brands include: Amatom, Concord, Globe, H.H. Smith, Lyn-tron, Microplastics, Keystone, Pem, RAF, Unicorp.

Finally, standoffs and spacers sometimes show up under their Mil-spec numbers, which can be crossed to commercial equivalents. Some common Mil-spec series include NAS42, NAS43, NAS61, NAS1056, NAS1057, NAS1829, NAS1831. Where applicable, these Mil-spec parts will be DFAR compliant with full paperwork.

Contact me at robin@mfsupply.com with your questions, comments or helpful hints!


Buyer’s Guide for Using Functional Equivalents to OEM Brands

5 Things to Know when Comparing Fastener Brands to Generic Alternatives

This year, we’ve discussed how the trademarked brand Keensert® is often available as a Mil-Spec or generic branded key-locking insert. We also reviewed how national brands of precision shoulder screws, such as Amatom, Concord, RAF and others are also offered by McMaster-Carr (tight tolerance series), MSC, Grainger and generically.

But how exactly do you determine which categories of fasteners cross to generic alternatives? This guide offers creative solutions including when to cross, and how to save money and reduce long lead times by using brand alternatives.

1.  What is a functional equivalent when it comes to fasteners and precision components?  

You can find hundreds of registered trademark-branded fasteners and components in the industrial marketplace. Much like brand-name pharmaceuticals such as Tylenol and Advil are available generically (as acetaminophen and ibuprofen), some brand name fasteners are also available as “generics,” “crosses,” “alternatives” or “functional equivalents.”

In the world of fasteners, a functional equivalent fastener is a part that is the same as the brand-name product in form, fit and function, including material and plating specifications.

2.  How can I determine if I must use the brand name or if I can cross to a generic part?

Before you shop, check the bill of materials to see if it specifically calls out a particular brand name along with the part number. If no specific manufacturer’s name is listed, then you can typically use a functional equivalent.

Use this handy 4 point checklist as your guide:

  • Does your bill of materials specifically call for the OEM brand-name fastener or component?
  • Can you live with the lead time or will having parts sooner improve delivery of the final product?
  • Will your supplier provide a certificate of conformance?
  • Will saving money help you be more competitive?

3.  What categories of fasteners are available as generic or functional equivalents?

Popular categories include adhesives and sealants, anchors, bits and nutsetters, cage nuts, flex type lock nuts, handles, Keenserts, knurled thumb screws, nylon insert stop nuts,  precision shoulder screws, retaining rings, rivets & blind threaded inserts, self-clinching, fasteners, spacers and standoffs, speed clips, spring nuts, weld nuts, weld studs, and woodworking screws.

4.  What brands of fasteners should I consider crossing to their generic or functional equivalent?

A sample list of brands that have generic alternatives: 

3 STAR RIVETS USA, ABBATRON®, ALCOA, AMATOM®, APEX®, ARCONIC®, ATLAS®, AVDEL®, AVK®, B. F. GOODRICH, BOLLHOFF, BUCKEYE, CAPTIVE, CELUS®, CHERRY®, CONCORD, FASTENAL, GESIPA®, GRIPCO®, GLOBE ELECTRONICS, H. H. SMITH, HUCK, INDUX, INTERFAST, KEYSTONE, LOCTITE®, LYN-TRON, MACLEAN­ESNA®, MARSON®, MCMASTER-CARR, MISUMI, MSC INDUSTRIAL, PEM®, PIC DESIGN®, POP®, POWERS®, QUICKSCREWS, RAF, RED HEAD®, ROTOR CLIP®, SHEREX, SIMPSON, SOUTHCO®, SPS TECHNOLOGIES, TINNERMAN®, U. S. ANCHOR. VIP, W. M. BERG, W. W. GRAINGER, WALDES TRUARC®.

5.  What are the advantages of using functional equivalents?

Brand names are great, and when they are in stock, available and required by your customer, then you can buy them with confidence in their quality. However, one surefire way to save money and shorten delivery time is to cross the OEM brand part on your bill of materials to a functional equivalent.

Brands and Functional Equivalents at MF Supply

Supplying a full range of fastener products and services, MF Supply is an authorized distributor of Amatom/Carey, Captive (Pem equivalent), Chrislynn Inserts, Concord, EZ-Lok, Lok-mor, Lyn-tron, Microplastics, Shear-loc, S&M Retaining Rings, and Unicorp, as well as a distribution partner for many others. We have an expertise in dowel pins, inserts and Keenserts and domestic and Mil-Spec products.

We provide functional equivalents to expensive brand name fasteners and help our customers save money while reducing long lead times. Check out our recent case study where a functional equivalent was substituted for an OEM brand, reducing costs by 37% and shaving lead time. This time and money savings gave the manufacturer an advantage over their competition, which helped them win the job.

For more detailed information about brands we commonly cross, visit our website. And if you don’t see it listed, as always, ask us. “Finding the right screw for you” is our tag line after all!

MF Supply is a WBE/WOSB certified stocking distributor of precision fasteners and electronic components, specializing in precision hardware including precision shoulder screws. For more than 40 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.