Tag Archives: self drilling screws

Self-Drilling Screws – How They Work

Self-Drilling Screws eliminate the need for separate drilling and tapping operations, helping provide the user with a faster, more economical installation process. Self-Drilling Screws operate on the same basic principles as a drill bit or other cutting tool. Performance for these screws are determined by cutting speed, feed rate, depth of cut and the working material being drilled into.

Optimal Performance Conditions for Self-Drilling ScrewsOptimalCuttingConditionsScrewSize

Proper installation of self-drilling screws depend on a number of factors and can (mostly) be controlled by the user. The table to the right, can be used as a guide to help properly install different nominal screw sizes. *Suggested combined maximum values. Values may be increased or decreased, as long as associated variable are changed proportionally.

  • Screw Point Geometry – the shape of the self-drilling screw drill point, not directly adjustable by the user
  • RPM – the speed of the drill/driver motor while installing the screw. Can be adjusted using a variable speed drill/driver
  • Applied Force – a measurement of the force applied by the user as the screw is installed, more force is not necessarily better
  • Work Material Hardness – the material’s resistance to drilling or cutting, in most cases, the harder the material, the more difficult it is to drill/cutSelfDrillingScrewAnatomy

Important Features to Consider When Choosing a Self-Drilling Screw

When selecting the correct self-drilling screw for your application, there are a number of factors to take into consideration. This includes the types of materials being attached and the thickness of the materials. In addition to the working material, the following design features should be also be considered before selecting your screw.

  • Drill Flutes – allow the drilled material to exit the hole, once completely embedded, the flutes can no longer remove these chips. These chips contain approximately 80% of the heat created during the installation process. If these chips buildup, this could cause the point to over-heat and fail.
  • Point Length – determines the thickness of the material which the screw can dependably drill through. The pilot section of the drill point, unthreaded portion, must be able to completely drill through the working material before the threads engage. Fasteners can bind and break if the threads engage before drilling is complete.DrillPointWings
  • Point Wings – are not present on all self-drilling screws, they are used when you need to fasten thicker materials, such as wood to metal applications. When drilled, the wings will enlarge the hole in the fastened material, allowing the threads to pass through without engaging the threads. This added clearance prevents the separation of the materials being fastened together, known as jacking. The wings will then break away once the come in contact with the metal before the threads engage the metal.

Self-Drilling Screws Available at Tanner

At Tanner we offer one of the most complete lines of self-drilling screws available. Choose from: Standard Self-Drilling Screws, Bi-Metal Self-Drilling Screws, Self-Drilling Reamers, Structural Self-Drilling Screws, Tamper-Resistant Self-Drilling Screws & much more! If you have any trouble finding a particular size or style of screw online, please feel free to reach out to one of our knowledgeable product specials – Email: websales@tannerbolt.com | Phone: 800-456-2658

Don’t Forget About

  • Screw Drill Point Material – are usually plain carbon steel which is less stable at high temperatures. To help reduce the wear on the drill point, fasten using a motor drill rather than an impact driver or hammer drill.
  • High Temperature Failure – the heat generated when drilling in self-drilling screws affects how quickly the drill point fails. For additional information on this, please refer to the troubleshooting guide below.
  • Drilling Temperature – motor RPM, applied force and work material hardness, all contribute to the the drilling temperature. Increasing any of these values also increases the heat generated.
  • Reducing Applied Force – this can help increase durability, allowing the drill point to penetrate thicker materials.
  • Reducing Motor RPM – this can help improve the performance when drilling into harder materials. This will allow the user to push harder during the drilling process and extend the drill point life.

Drill Point Failure Examples

Elco’s Flex Technology Products are the Industry Leader in Critical Fastening

Elco’s Flex Technology Line of Products Far Surpasses Any Standard Fastening Format Available

Delayed embrittlement is a common, but potentially catastrophic downfall that standard case hardened fasteners are subject to. Delayed embrittlement is brought on by the presence of hydrogen, which is generated in dissimilar metal applications. To combat this problem, Elco Construction Products has developed a line of fastening products that utilize Flex Technology. These Flex Technology fasteners were developed for high performance and to be virtually immune to delayed embrittlement failures. These fasteners are manufactured with special alloy materials that have received proprietary heat treatments and tempering processes. Flex Technology fasteners enhance the performance of critical connections and all feature a multi-layered, durable Stalgard corrosion resistant coating. Read on to learn more about some of these great Flex Technology Fasteners that are available to you.

Dril-Flex® Structural Self-Drilling Fasteners

Virtually Immune to Hydrogen-Assisted Stress Corrosion Cracking for Maximum Performance

Dril-Flex® Structural Self-Drilling Fasteners are designed to help prevent hydrogen-induced brittle failures. These fasteners are tested in accordance to ASTM standards, Dril-Flex® fasteners have proven to provide the same resistance to hydrogen-assisted cracking (HAC) as a Grade 5 fastener. Dril-Flex® fasteners are developed with the unique Flex Technology dual-hardening process. These fasteners are then finished with a silver Stalgard coating to provide a superior corrosion resistance and enhanced galvanic compatibility. The combination of the dual-hardening process along with the Stalgard coating, result in making Dril-Flex® fasteners the ideal fastening solution for demanding construction applications.

Features & BenefitsDril-Flex® Structural Self-Drilling Fasteners

  • Self-drilling point to ensures consistent, reliable drilling and tapping
  • Eliminates separate drilling and tapping operations
  • Higher hardness point and lead threads (HRC 52 min.)
  • Lower hardness load bearing threads (HRC 28-34)
  • Silver Stalgard corrosion resistant coating – superior to zinc or cadmium-based finishes
  • Virtually immune to delayed HASCC brittle failures
  • Provides the same high resistance to hydrogen-assisted failure as a Grade 5 fastener
  • Provides enhanced galvanic compatibility in dissimilar metal applications
  • Approvals: ICC ES ER-4780 Legacy Report; COLA (City of Los Angeles) Research Report #25095

Bi-Flex™ Bi-Metal Fasteners

Corrosion Resistance of 300 Series Stainless Steel and the Efficiency of Drill Screws

Bi-Flex™ Bi-Metal Fasteners utilize bi-metal technology to create a single, unique fastening system that resists visible corrosion and is virtually immune to hydrogen-induced stress corrosion failures. Bi-Flex™ fasteners are made from 300 series (18-8) stainless steel alloy to provide corrosion resistance in even the toughest environments. They feature a fused and hardened steel drill point and lead threads. This allows the Bi-Flex™ fasteners to quickly drill and tap structural steel and aluminum up to 1/2″ thick. These fasteners also feature a silver Stalgard® GB coating, a galvanic barrier helps protect aluminum components from accelerated corrosion when in contact with 300 series stainless steel. The dependability and ease of installation make Elco’s Bi-Flex™ Bi-Metal Fasteners the best choice for your toughest construction applications.

Features & BenefitsBi-Flex™ Bi-Metal Fasteners

  • Bi-metal technology – 300 series (18-8) stainless steel head and shank
  • Fused and hardened steel drill point
  • Quickly drill and tap into steel or aluminum up to 1/2″ thick
  • Silver-colored Stalgard® GB coating
  • Greater galvanic compatibility in dissimilar metal applications involving aluminum
  • Wide variety of sizes and head styles
  • Outstanding corrosion resistance and long service life
  • High strength, ductility, and reliability
  • Virtually immune to delayed embrittlement failures
  • High in-place value over the life of structures, components, and systems
  • Approvals: City of Los Angeles (COLA) Research Report: RR25886 (CSI #05 05 23)

Elco’s Family of Fastening Products Available at Tanner

At Tanner we pride ourselves on supplying you with the full line of Elco’s Flex Technology Fasteners, as well as their Metal Fasteners and Concrete Anchors. Some of these top brands include Aggre-Gator® Bi-Metal Masonry FastenersAlumi-Flex™ 302 Stainless Steel Self Drilling ScrewsTap-Flex® Thread Forming Structural ScrewsUltraCon® Masonry Fasteners, and much more! Along with all these great Elco fasteners, Tanner also offers a wide variety of Standard Self Drilling Screws. In our Self Drilling Screws Department you will find 18-8 Stainless Steel, 410 Stainless Steel, and Carbon Steel options.




How do I Choose the Correct Self-Drilling and Self-Tapping Screws??

Self-Drilling Screws

Self-Drilling Screws operate on the same principles as drill bits and other cutting tools. This means that the way in which these screws are used affects their performance as much how they are designed.

Two important factors to consider when selecting a self-drilling screw are, material thickness and types of materials to be joined.

Screw Suitability
Optimal Cutting Parameters by Screw Size







Key Design Features to Consider when Selecting a Suitable Self-Drilling Fastener

  • Drill Flute

    • The length of the drill flute determines the metal thickness that can be drilled. Drill flutes allow the drilled material to exit the hole. If the drill flute becomes completely embedded in the material, the drill chips will clog the flute and cause the cutting action to cease. If this occurs, the heat from the drill chips could cause the drill point to become over-heated and fail.

  • Point Length

    • The drill point is the unthreaded section from the drill point to the first thread. This length must be long enough to completely drill through the material before the threads engage. If the threads engage too early, they can cause the fastener to bind and break.

  • Screw Wings

    • It is necessary to use fasteners with wings when fastening wood, over ½” thick, to metal. The wings will ream a clearance hole and keep the threads from engaging too early. If the threads engage too early, this could cause a separation of the fastened material from the base material (jacking). Once the wings hit the metal material, they will break off allowing the threads to engage.


Self-Tapping Screws

Self-tapping screws can tap its own hole as it is being driven into it. They can come with a sharp, piercing tip or a flat, blunt tip. Sharp tipped self-tapping screws are designed for drilling their own hole in soft materials. The flat tipped self-tapping screws will need a pilot hole drilled before being installed. Some self-tapping screws are also self-drilling screws. These screws have a drill-like flute tip that looks like the tip of a center drill, along with the tap-like flute in the leading threads. These screws are very efficient in hard substrate applications.

How the Self-Tapping Ability is Created

  • Hard Substrates – Metal or Hard Plastics

    • Often created by cutting a gap in the continuity of the thread on the screw, this generates a flute and cutting edge similar to those on a tap.

  • Soft Substrates – Wood or Soft Plastics

    • The self-tapping ability can come simply from a tip that tapers to a gimlet point (no flute is needed), the point forms the hole by displacement of the surrounding material rather than any chip forming drilling/cutting/evacuating action.

Know Your Torx® Tamper-Resistant Screws

Torx® Tamper-Resistant Screws

Torx® Tamper-Resistant Screws are characterized by their unique, six point, star shaped pattern. The star design provides various benefits, including preventing cam-out and increased ease in maintaining a consistent torque. Torx® Tamper-Resistant Screws contain a solid post formed in the middle of the recess during the heading process. The solid post blocks the insertion of an ordinary Torx screwdriver or any other driver. This added security feature makes it nearly impossible to remove without a unique tamper-resistant tool. Torx® Tamper-Resistant Screws that are available at Tanner are: masonry screws, self-drilling screws, sheet metal screws, and cap screws. Continue to read below for more information about each type of Torx® Tamper-Resistant Screws offer at Tanner.

Torx® Tamper-Resistant UltraCon® Masonry Screws

Torx® Tamper-Resistant UltraCon® Masonry Screws

Torx® Tamper-Resistant UltraCon® Masonry Screws are the perfect combination of the security of a Torx® tamper-resistant drive and the superior quality and easy installation of an UltraCon® masonry screw. These screws are the optimal fastening solution for use in concrete, brick, or hollow block. The special Hi-Lo threads on the Torx® Tamper-Resistant UltraCon® Masonry Screws lead to a greater resistance to pullout and also creates stronger fastening in masonry materials. These tamper-resistant masonry screws are coated with Stalgard® finish to provide superior corrosion resistance. The Stalgard® finish helps prevent red rust and other base material corrosion on significant surfaces, even after 800 hours of 5% neutral salt spray exposure (ASTM B117).

Torx® Tamper-Resistant Self-Drilling Screws

Torx® Tamper-Resistant Self-Drilling Screws

Torx® Tamper-Resistant Self-Drilling Screws eliminate the separate drilling and tapping operations for a faster, more economical installation process. This is possible because the Torx® Tamper-Resistant Self-Drilling Screws have a sharp, clean and consistent drill point, excellent thread engagement and holding power. What makes the Torx® Tamper-Resistant Drive System one of the most efficient fastening systems available is its ability to transfer greater torque, reduce end load, and virtually eliminate tool slippage. These fasteners are nearly impossible to remove without the special tamper-resistant Torx® Drive tool. Torx® Tamper-Resistant Self-Drilling Screws offered at Tanner are: pan head screws made from hardened 410 stainless steel, button head and flat/oval head screws, which are both made from zinc plated case hardened steel.

Torx® Tamper-Resistant Sheet Metal Screws

Torx® Tamper-Resistant Sheet Metal Screws

Torx® Tamper-Resistant Sheet Metal Screws are a high strength, one-piece, one-side installation fasteners, with the unique ability to “tap” their own mating internal thread when driven into preformed holes in metallic and nonmetallic materials. These screws have the ability to form or cut their own mating thread, creating an unusually good thread fit, which enhances resistance to loosening in service. They also have the ability to be disassembled and are generally reusable. Torx® Tamper-Resistant Sheet Metal Screws offer at Tanner are: button and flat head screws. Each head style is made in zinc plated case hardened steel and 18.8 stainless steel.

Torx® Tamper-Resistant Cap Screws

Torx® Tamper-Resistant Cap Screws

Torx® Tamper-Resistant Cap Screws have many of the same security features as the Torx® Tamper-Resistant Sheet Metal Screws. These screws are used in facilities where tamper-proofing is essential to reduce vandalism, tampering, and theft. Tanner offers three head style of Torx® Tamper-Resistant Cap Screws: button head, flat head, and flat head undercut. Each head style is made in zinc plated case hardened steel and 18.8 stainless steel.



Fastener Facts and FAQs

Keeping up with technology is a challenge. Each new gadget has a different feature than its predecessor, but who really knows the difference between the two? If you want to know the difference between the iPhone4 and the iPhone5, you ask someone who works for the company. If you want to know the pros and cons of HDTV versus 3D, you ask somebody in the television industry. If you want to know about construction fasteners, ask us. Below are some questions we are asked more often than others.

What type of screw gun should be used to install self drilling screws?

For optimal performance, the screw gun should meet the following characteristics:

  • 1800 to 2500 RPM variable speed
  • 6 to 8 amp motor
  • adjustable torque sensitive clutch mechanism
  • depth adjusting nosepiece

What is the difference between a self drilling screw and a self tapping screw?

Just because the names sound similar doesn’t mean they are one in the same. A self drilling screw is designed with a drill bit point. That special point helps to drill into metal without requiring holes to be pre-drilled. Primarily used for metal only, self drilling screws are also known as “tek” screws.

A self tapping screw, on the other hand, has a sharp point with threads and is usually designated as either type “A” or “AB”. (The difference between the two types is the thread size and pitch.) A self tapping screw carves its own thread as it’s being installed, similar to a tap. The difference lies in the fact that a self tapping screw, unlike a tap, requires a pre-drilled hole.

What is the difference between 304 and 316 Stainless Steel?

Not only does the shape of the screw, the style of the tip or the pitch of the threads matter, so does the material that makes up the screw. 304 Stainless Steel contains 18% chromium and 8% nickel. Molybdenum (“Moly”) is added in the 316 Stainless Steel so the percentages differ slightly, with 316 containing 16% chromium, 10% nickel and 2% molybdenum. The purpose of adding the moly is to help the fasteners last longer by resisting corrosion to chlorides like salt water or de-icing materials.

What is a flat undercut screw head?

There are circumstances in which you need more thread and less head in a small amount of space. Flat undercut screw heads are supplied to allow more room on the body of the screw for usable thread. The head height of undercut screws is approximately two-thirds the height of standard flat head screws. Drive depths are reduced proportionately.

Is there a security nut available that cannot be removed?

Security fasteners protect property from theft and misuse. Security screws are constructed with specialty heads that prevent any unauthorized person (anyone without the proper, hard-to-obtain tool) from removing them. And, yes, there are security nuts, too. After tightening to the proper torque, the hex section of a break-away nut shears off leaving a conical nut that cannot be removed.

Specialty Fasteners Save Time and Money

If you are a maintenance technician or installation contractor, you know the value of specialized security fasteners or self drilling screws.  Although these fasteners cost a bit more when you pick them up at the local supplier, specialized security fasteners speed up a job, saving the contractor and the project owner both time and money.

One of the recent applications of self drilling screws is in the area of steel stud construction. In the past, commercial buildings and homes were constructed entirely of wood studs and structural members. In the 1980’s and early 1990’s, because of the abundant supply of scrap and recycled metals, steel studs entered the market at competitive prices, and they feature a number of competitive advantages.

Steel studs are lighter than traditional wood framing materials. They don’t have to be drilled for access holes for electrical and plumbing, because the wide side of the stud is already designed with access holes. Installation contractors cut steel studs with a tin snip they carry in their tool belt rather than high power circular saws. Steel studs are fastened together with sell drilling screws, that are both lighter and less expensive than 3 ½ inch long spike nails.

Steel studs are only one application for self drilling screws. Any sheet metal fabrication project is faster and easier with using a self drilling screws, and self drilling screws are used extensively in manufacturing. The screw serves as its own drill bit. Thus the installation contractor can insert the screw in one step, instead of two.

Another important fastener for commercial and industrial contractors are tamper-proof screws and anchors. Often seen in public bathroom stalls or other building projects used by high numbers of the general public, the heads of a tamper proof screws are custom shaped so that both installation and removal requires specifically manufactured tools.

Tamper proof screws originally appeared in the marketplace as a modified slotted screw. The head of the screw was shaped so that it could be turned into place, but it could not be removed by a standard flat head screwdriver. These fasteners could only be used once, because removing them from the wall usually destroyed the fastener’s appearance.

Today, with the wide acceptance of Torx and square drive style fasteners, tamper proof fasteners have been redesigned. These fasteners are called pin-head security fasteners. In the center of the Torx, or Square slot is a small pin. Installation contractors must have a specialty designed tool to install, or remove this fastener.

So when you are looking for a supplier for industrial tools and fasteners, make sure you select a supplier that can ship the right part the first time, and on time. You will want to find a partner that can provide a wide selection of parts, grinding wheels, and the tools which go with them. Another advantage for the installer is finding a partner company that can provide all your specialty fasteners and tools from one location. Maintaining an efficient and profitable shop is much simpler when you can go to one supplier and order all your regular shop supplies. Picking a partner who will ship quickly, reliably can help your shop run smoothly, which creates satisfied customers, and a growing business.

The Right Type of Fastener Can Make the Difference Between Success and Failure

Please find the following informative article detailing the use of selectively-hardened fasteners Bi-Flex and Dril-Flex in the construction of the Adrienne Arsht Center for the Performing Arts in Miami, Florida.

Selectively hardened fasteners with corrosion-preventative coating protect the integrity of the structure and avoid the dangers of hydrogen assisted stress corrosion cracking (HASCC), also known as delayed hydrogen embrittlement. In exterior applications or aggressive interior environments, bi-metallic or superalloy fasteners are recommended.

Labor-reduction associated with the new super alloy fasteners is expected to result in even more significant overall savings, especially on high-rise structures.

Please read further in the following pdf article, Small Details, Big Consequences

Making the Right Connections: Avoiding Metal Fastener Failures

In life, success often depends on paying attention to details and making the right connections. When fastening metals together, it is no different. The wrong connection can cause significant failure. In common construction applications fasteners can spontaneously fail for no apparent reason. These failures may occur shortly after installation or even months or years later leaving the contractor, building owner and other responsible parties puzzled over the cause of failure and cost of remedy.

The following presentation by Gregg Melvin with Elco Construction Products identifies the risks and offers solutions so that the right fasteners are used on your  job.

Making the Right Connections: Avoiding Metal Fastener Failures (PDF)