– By Tom Hulsey, Sealtite –
Fasteners and fastening systems have evolved steadily over time. History has led us from the use of nails as the fastener of choice to today’s self-drilling screws as the most versatile means of securing one piece of material to another in the steel building and post framed building industry.
Nails, as a means of fastening wooden objects, date back to approximately 3400 BC in ancient Egypt. The term “penny” probably originated in medieval England to describe the price of 100 nails. The “d” that is used as abbreviation for penny is derived from Latin for the name of the Roman coin, Denarius.
Until the early 1800’s, nails were made by hand. Around 1800, cut nails (square nails) were made from wrought iron. Around 1860’s, wire nails were introduced and by early 1900’s, 90% of all nails were wire nails.
Screws, on the other hand, date back to 3rd Century BC in Greece. By the 1st Century BC, screws were commonly used throughout the Mediterranean area in screw presses in the processing of olive oil and grapes.
The spiral thread has proven over time to be an effective means to provide the force needed in order to perform specific tasks. Just as nails were originally made by hand, screws were likewise made by hand for use in the assembly of materials to form a secure attachment of one piece to another. Originally, there were no standards to guide the making of the screw. Consequently, there was no chance of having screws to be interchangeable from one application to another. The screw, therefore, was a custom fabrication for one specific application.
The development of screws and screw thread forms occurred around 1800 with the development of a modern screw cutting lathe. Screws could be made more precisely and therefore could be produced much faster than before. Consequently, the development and standardization of thread forms became important for reproducibility and interchangeability in use.
In the late 1860’s and early 1870’s, the US Standard Thread was created. Thread designs and thread forms continued to evolve. Sometime around 1916, the SAE Standard (Society of Automotive Engineers) was established in order to augment the US Standard. This standard defined thread forms and specifications for threaded fasteners for general use. These standards were later adopted by ANSI (American National Standards Institute). IFI (Industrial Fasteners Institute) is also a standards publisher that defines thread forms for fasteners.
My first involvement with threaded fastener standards was in the mid 1960’s. At that time, the most common fastener used in the metal building industry to attach roof and wall sheeting to the girts and purlins was a #1/4-14 Hex Head Type B self-tapping fastener. The roof sheeting side laps used a #14-10 Hex Head Type A fastener to secure the laps. Both fastener types required a pre-drilled hole in the assembly in order to be installed. Installation required two tools and often two workers to install the fasteners; one to drill the holes and a second worker to install the fastener.
By the late 1960’s, self-drilling fasteners were making their way into the metal building market. Self-drilling fasteners were new and were also relatively expensive as compared to the self-tapping Type A and Type B fasteners that were commonplace at the time. The first self-drilling fastener to be introduced was described as a “milled point” self-drill. That name described the operations required to create the drill point on the end or the screw. A typical metal building self-drilling fastener required a minimum of four cutting (milling) operations to produce the drill point geometry.
By the late 1960’s and early 1970’s, a new technology self-drilling point was introduced to the metal building industry. It was described as a “pinched point” (cold forged) self-drill. This new point required only one operation to form (pinch) the point on the end of the fastener. That process employed the use of a machine equipped with hardened dies that were configured to match the desired shape of the point. As the fastener passed into position, the dies were closed and the point was cold formed on the screw in one operation. This process was faster and more consistent in production of the self-drilling screw.
The obvious advantage of using the self-drilling fastener was the reduction in the overall time and cost of installing the fastener. The self-drilling fastener did not require a pre-drilled hole to be installed. It was still a hard sell in the early years because the self-drilling screws were considerably more expensive to purchase. Eventually, the economics of a one-man operation to install a fastener became evident. Today, the self-drilling fasteners are used almost exclusively for securing wall and roof sheeting to girts and purlins in the metal building industry.
Until the mid 1970”s, nails were the fasteners of choice for attaching metal sheeting to wood framed buildings. The early nails were equipped with malleable lead heads or a loose disc of rubber under the nail head to effect a seal at the nail penetration through the metal panel. The nails were generally placed at the high point of the corrugations to reduce the chance of leaks when the nails worked loose. One building owner once said, “Put the nails in the top where the water doesn’t run.” With the introduction of screw fastening and high performance EPDM sealing washers, fastening in the flat portion of the panel became the best location for both structural and weatherproofing integrity of the roof system.
Self-drilling fasteners continue to evolve in form and in function. Continually advancing technology in the design of heading, threading, and pointing equipment has produced cost effective solutions for virtually every fastening challenge. Specifically designed thread forms provide higher strength structural connections at the purlin/ girt /metal panel connection. New alloys are being developed in conjunction with innovative hardening processes to provide a new generation of self-drilling fasteners with exceptional performance capabilities. Improved finishing technology has provided exceptional corrosion protection and appearance of the installed fastener. Enhanced UV and Ozone resistant metal sheeting finishes and “Green” technology continue to improve the overall quality of the building structure. Proper installation tools for fastener installation are now on the forefront of the development challenge.
The past fifty years have provided a exciting ride along the evolution trail of the pre-engineered metal framed and wood framed building fastening industry. As the building technologies continues to grow, I would expect the next fifty years to be just as exciting. I can hardly wait!!!