Tag Archives: Failures

A “Galling Development” – What Every Distributor Should Know about Thread Galling

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Reprint from LINK, Spring 2021

A number of year’s back I was engaged by a Midwestern distributor to review an application problem that had intermittently plagued one of their more important customers. Upon meeting with their customer, I learned the problem occurred during the assembly of a stainless steel Nylon insert lock nut to a like stainless steel screw. Although this was a sporadic problem, when it occurred the customer would experience assembly difficulties like nuts that were very hard to turn, nuts that reached installation torque levels before seating, and in the worst cases, nuts that became totally frozen (seized) in mid-run down position, often breaking the screw in torsion.

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The Basics of Fastener Sorting

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From Link Magazine, Summer 2014

Over twenty-five years ago when I first started working in the fastener industry PPAP, ISO9000, and zero defects were not yet commonplace ideas. In fact, when I first started, sorting was all manual and reserved pretty much only for salvaging parts that a customer returned with a major problem. Today, it is a very different story. A large percentage of fasteners made or sold in the U.S. are sorted, with some companies serving certain industries or customers adopting the philosophy of sorting 100% of their
parts.

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Galvanic Corrosion: Knowing How It Works and Steps to Protect It Are Important

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From Fasteners Technology International, April 2014

Anyone that has ever worked on rehabbing an older home has probably encountered a plumbing connection where an old galvanized steel pipe that has been connected with a newer copper fitting such as shown in Figure 1 is in bad shape. The discovery of this condition may be purely accidental, or more likely, if such a connection has been in-place for any length of time, the ticking time bomb represented by this condition has finally gone off and it is leaking or broken.

So what is this condition? It is a classic case of galvanic corrosion. Fastener engineers, designers and end users, especially in instances where metals are being clamped in wet environments, must be very wary of this possibility and make efforts to avoid future 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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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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