Tag Archives: Screw Threads

New Flat Die Thread Rolling Technology

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Reprint from China Fastener World Magazine, Vol. 189

One of the delights of being an independent consultant is the wide assortment of people I meet and projects I get to review. Over the last ten years the two problems that I am most commonly approached about include skills development and thread rolling. In fact, I have written many articles in the last ten years and the one that I most frequently have inquiries about years later is related to problems in thread rolling. This is truly a step in the fastener manufacturing process that is ripe for innovation.

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Thread Rolling Machines

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Reprint from China Fastener World Magazine, Vol. 189

I started my career in the fastener industry between my third and fourth year of university. Although it’s been thirty- four years now, I can remember almost like yesterday the first time I got to walk around a fastener manufacturing plant. Of course we started in the heading department and seeing headers paying off wire and spitting out parts was very exciting, but it was the rolling operation that really left a lasting impression on me.

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Bi-Metallic Drill Screws

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Reprint from China Fastener World Magazine, Vol. 186

In construction applications where predrilled and tapped joint members are impractical, Drill Screws are an exceptionally versatile and helpful fastener product. Drill Screws can be easily assembled into and through a wide assortment of building materials without the need for any access to the back side of the joint. The application opportunities are abundant both for interior and exterior purposes. Drill screws are excellent resources on the interior, where they are commonly utilized to attach gypsum board, wood members, and other metal components to metal structural members and studs. Generally, the interior environment is controlled and these screws are not subject to challenging or abusive environmental conditions. Drill Screws are also highly favored by installers of metal roofs and cladding. Drill Screws provide an easy way to pierce the metal roof or cladding sheets and the underlying steel structural components without the need for any predrilling of pilot or clearance holes. Unlike interior environments, however, the exterior of the building will be subject to whatever variable environmental conditions the climate zone is known for.

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Screw Threads – Different Designs and Where They Are Utilized

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Reprint from Fastener World Magazine, Vol. 163

In recent years a new addition to public school curriculum has taken the US by storm. This addition is known as STEM, which is an acronym for “Science, Technology, Engineering, and Mathematics”. One of the foundational subjects of the STEM curriculum is education about the “Seven Simple Machines”. As a student of technology, each of these simple machines is an interesting subject, but perhaps none of the seven is more elegant than the screw thread.

Since its first inception and surely its first recorded uses, the screw thread has been faithfully serving mankind in many ways. One of the first recorded deployments of the screw thread was when Archimedes used it to move water from one level to another, and today it’s uses for holding things together are almost limitless and span from the very mundane to the very important and critical. In fact, today many in our society are thankful for screws that hold bones and other body parts together, enabling revolutionary remedies to common health and mobility problems.

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Strategies To Mitigate Fatigue Failure in Fasteners

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From Fasteners Technology International, August 2013

Although component failures have probably been around for as long as man has been putting things together, it wasn’t until the early to mid nineteenth century that engineers began studying the progressive failure mode that we know today as fatigue. Although highly undesirable, fatigue is a relatively common failure among fasteners and regretfully can lead to some dramatic and even life-threatening consequences. A great deal of progress in understanding fatigue has been made since the nineteenth century, and yet there is still much to be learned. Fortunately, enough is understood today that specific strategies and practices can be employed when a bolt or screw is designed in an application at risk of fatigue failure. This article will look at the basics of fatigue in fasteners and preventative measures that can be adopted to reduce the risk of failure and improve the durability or life of the fastener component.

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The Art of Thread Forming Fasteners, Part Two – Thread Forming Into Plastics, Light Metals, and Steels

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From Fastener Technology International, June 2013

In Part One of this two-part series, we looked at the general principles of thread forming that apply uniformly regardless of screw or material type. In an ideal world, “one size would fit all” and any screw could be universally used in any material. However, anyone that has ever tried to thread a standard sheet metal screw into polycarbonate or into a thick steel plate might attest to catastrophic results. Why? Quite simply, the fastener being used was never designed to perform in these materials.

Therefore, the first ground rule that any Fastener Engineer or Designer must employ is to choose a fastener that was designed to work in the material and the situation intended. There is some excellent fastener technology that works well in the applications it was designed for, but not so well with other materials. So it is incumbent on the Designer to know as much as possible about all aspects of the joint and not to simply assume that because the fastener works well in thread forming such-and-such a material, that it will work well in a different one.

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The Art of Thread Forming Fasteners, Part One – General Principles

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From Fastener Technology International, April 2013

One of the roles of every Fastener Engineer or Designer is to look critically at each new problem and develop an elegant solution that is as simple in form as it is effective in practice and efficient in cost. That often means using the minimal amount of resources to gain the maximum achievement. The “art” of thread forming fasteners provides a powerful tool in the industry arsenal to achieve such results for customers.

When it comes to fastened joints made up of a threaded fastener and some type of nut member, there are really only two varieties, those that start with a nut member thread already in-place and those that depend on the threaded fastener to create its own mating thread. A great deal of technical information can be found where both screw and nut member are threaded, but far less is available and understood on those where the nut member thread is formed by the screw itself.

This two-part article series will attempt to remove some of this mystery. Part One will explore the basic guiding principles of thread forming. These are principles and behaviors that are true regardless of the screw or nut member material. When I am done, it is my hope that the reader will have gained an appreciation for how thread forming works and the general areas of concern for the Fastener Engineer when he or she designs such a joint.

Part Two will explore the more specific and specialized cases of thread forming into thermoplastic, light metal and steel materials. Although not the only materials available for thread forming, these three categories represent the majority of areas where thread forming fasteners are utilized today.

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Are You Familiar With Common Failure Modes On Roll Threaded Products?

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From Fastener Technology International, December 2012

I can vividly remember the first time I walked onto the manufacturing floor of a fastener manufacturer. I was not a rookie to a manufacturing environment, having spent the previous two years in a large metal stamping facility, but the “rat-tat-tat” sound of multiple headers banging out hundreds of parts a minute was a big departure from the “ker-chunk” sound of a 2000 lb press forming a car’s hood or quarter panel that I had grown accustomed to. Although the headers were center stage and what I would subsequently naturally showcase during hundreds of plant tours in the years afterward, it was the humble thread roller that left an indelible memory during that first plant tour.

I suppose this impression was far less the result of any impressiveness of the machine itself and more on the ingenuity and complete unexpectedness of the rolling process. At that time, my paradigm was shaped from the only experience I had in threading a bolt, and that was using a tap and die set on my garage workbench. I guess I simply assumed that all threaded fasteners employed a tap or die in some fashion.

Therefore, I was fascinated to see parts being rolled between two flat plates at speeds so fast that they obscured the parts and transformed them into an unrecognizable blur. I walked away transfixed and appreciative of the creativity and ingenuity of some long past engineer. It would only be much later that I would fully appreciate the art of this process, but also the multitude of ways that it could produce defects and defective parts. This article is not intended to be an in-depth and detailed look at process, dies, set-up or any number of other factors that play a part in the conditions of the end product, but rather a brief introduction to the common failure modes that can result from thread rolling.

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