Varied in size, sometimes so small they escape notice, fastener products have become part of our daily lives and are indispensable for the development of modern industry and technology. Consider tables, chairs, cabinets, or the appliances we use every day, or even the assembly parts of a car or a missile launched into space for exploration.
The list could go on indefinitely because to truly understand what fasteners are, one must imagine a vast range of products applicable in various systems and sectors. The simplicity of these components hides meticulous design that has reached today's levels over a long time. In this article, we will tell the story of fasteners, get to know the inventors of screws and bolts, and trace the most important steps that have led to the fasteners as we know them today.
The History of Fasteners
When and where were screws invented? This is the first question to ask to trace the history of fasteners. The answer has distant roots in ancient Greece. According to some scholars in the field, the inventor of the screws was the Greek mathematician Archytas, who founded what we know today as engineering science during his lifetime, from 428 to 347 BC. Over the centuries, screws underwent a slow evolution until the Industrial Revolution, when production was standardized and optimized, also thanks to the invention of threading.
The Birth of Bolts
From the 1st century BC, history tells of the appearance and use of wooden screws to support structures such as presses used for olive and grape pressing. In the following years, such wooden elements were used for assembling war machines and for the construction of monumental architectures that have survived to the present day. The transition to metal screws occurred in Europe during the 15th century. From then on, the production of fasteners never stopped but evolved to reach exponential numbers, enormous variability of elements and sizes, adaptable to any application.
The Evolution of Bolts in the Renaissance
The 16th century saw the appearance of the first metal screws. They were unique and not interchangeable, so they could not be replaced with other products. As mentioned earlier, technologies changed very slowly, and it took over 200 years before a significant change in the production and application of fasteners was recorded.
It was in 1797 when, in England, engineer Harry Maudsley patented the first lathe capable of producing screws with repeatable and precise technology. This new tool was designed with an adjustable support that allowed for greater precision in machining, unlike the pedal-operated lathes used until then, which returned low-quality products. The invention of the British Maudsley allowed for the standardization of thread sizes, making nuts and bolts interchangeable. Until then, each bolt corresponded to a unique nut, but with the standardization of threads, any bolt could fit any nut, as long as they were the same size.
The Industrial Revolution and Fasteners
A particularly important historical moment for fasteners was the Industrial Revolution. The technological progress of this period allowed for the external powering of lathes, thus overcoming the traditional manual power. From that moment on, the production of screws and bolts soared, reaching mass production and commercialization levels.
Along with standardization, there was another problem to be solved for evolution to truly become exponential: finding a criterion that determined a unified type of threading to which all manufacturers could conform. In this regard, engineer Joseph Withworth marked the history of fasteners.
Withworth, a professional who had worked in many mechanical companies, including Maudsley's in London, opened his company near Manchester in 1833. From there, in 1841, he developed a range of screws that had a triangular thread with a 55-degree angle, with the pitch and size increasing according to the diameter of the screws. This invention, known as the Withworth system, became the first fastener unification system adopted by the British Standard. Initially spread based on agreements with other mechanical sector companies, this type of threading became widely used for two main reasons:
The Crimean War. In 1855, the United Kingdom had to quickly assemble a fleet of 120 gunboats equipped with steam engines. The need for rapid production prompted British authorities to involve many mechanical companies that needed unambiguous instructions. For this reason, the Admiralty prescribed the use of screws complying with the Withworth standard.
The British Railway Lines. It was the years of building railway lines in the United Kingdom, and the various companies each used their standard screws and fasteners. Again, the British authorities, who managed all the railway lines, gave instructions to use the Withworth system, encouraging its spread throughout the mechanical industry.
The BSW (British Standard Withworth) is still today the British standard for measuring screws used in engineering laboratories worldwide.
Screws: From Ancient to Modern
The historical milestones described so far are the most significant steps that have marked the evolution of screws and bolts. From the very first ones made of wood to those made of metal, screws represent fastening elements that have traversed time and are now produced in various types and materials.
Materials and Technologies
Characterized by a head, a shank, and a tip, screws have always been used to fasten objects or parts of them together. Although their function has remained unchanged over time, production technologies have evolved and improved. Today, the three main technological processes used to produce screws are:
Chip removal
Hot plastic deformation
Cold plastic deformation
For each production type, specific materials are recommended. For example, for chip removal (the oldest system), materials that are too hard or pasty should be avoided, while for hot deformation, more malleable materials such as steel, aluminum, copper, and brass are preferred.
Types of Screws and Their Uses
From the Withworth system to the present day, various types of screws have been studied and created, applicable to equally different sectors and purposes. Among the main ones, we remember:
The birth of nuts is concurrent with that of screws: these elements share the type of threading, and their use has always been closely associated. Indeed, even for these threaded hole fastening elements, the historical reference is the Withworth system, which spread the idea of no longer using unique pieces but standardizing the production of screws and nuts.
Different Types of Nuts
Used to hold materials on which they are applied together, nuts are produced in various shapes and sizes. Among the various types of existing nuts, we find:
The Importance of Nuts in Construction and Engineering
The variety of nuts available on the market today perfectly meets the different needs of customers and builders. Indeed, different nuts are applicable to sectors such as:
Curtain walls: this type of construction falls within the field of light carpentry and involves the use of steel, aluminum, and plastic materials;
Road construction: to make road constructions safe and robust, fasteners are essential. For these works, steel or hot-dip galvanized nuts are preferred;
Rock wall consolidation: for this type of work, metal meshes are used in combination with various fastening elements, including steel nuts.
Bolts: Pillars of Engineering
Evolution of Bolts
The bolt is a joining element that unites two mechanical parts and is formed by a screw and a nut. The assembly of these components follows certain classification schemes to align with national and international regulations. Therefore, markings indicating their characteristics are present on the bolts.
The historical evolution of the bolt is inevitably linked to that of the two elements composing it. Asking when the bolt was born means, in fact, wondering when the screw and the nut were born. Also in this case, the widespread diffusion occurred following the outbreak of the Industrial Revolution with a consequent mass production and standardization of processing procedures.
Its application has also developed over time in numerous sectors. Today, this threaded element is essential in many areas such as the metalworking, energy, petrochemical, renewable resources, transportation, structures, and large constructions.
Types and Features
As anticipated in the previous paragraph, to uniquely recognize a screw or a nut, it is necessary for these elements to have the so-called markings, incisions that the manufacturer must apply and describe the basic characteristics of each element. In general, the marking is made on the head of the product by engraving or relief.
For example, a class 8.8 indicates products made of medium carbon steel and is considered the most common form of high-strength material.
Bolts in the Modern World
The fields of application listed above for screws and nuts inevitably also apply to bolts. These joining elements find space in modern constructions and the industry as:
Even in a seemingly static sector like fasteners, innovation marries technologies and production methods. Today, even bolts become cutting-edge elements thanks to a sophisticated preload measuring transducer. This mechanism, developed in some modern manufacturing companies, involves installing an integrated laser system in the bolts that instantly identifies preload loss in joints and allows for immediate intervention. It is, therefore, a real-time system that makes bolts even safer and more reliable.
The Future of Bolts, Nuts, and Screws
If the first screw was made of wood, what will be the future of bolts, nuts, and screws? In this overview of the history of fasteners, the arrival point (at least for now) might be Artificial Intelligence applied to bolts. New fastening elements equipped with high-tech sensors have been designed, making them always connected. These components will not only fulfill their original mechanical functions but will also collect data never acquired before. Thus, bolts become intelligent and communicate, continuously improving the system they are applied to and its safety.
Case Study: Specific Uses of Fasteners
Fasteners in the Aerospace Sector
Thinking about the future of fasteners inevitably means thinking about their application in the aerospace field. Fastening elements for the aerospace sector are indeed components that must necessarily meet high standards and specific criteria to ensure ever-increasing safety.
These elements must resist high pressure, speed, wind, unstable temperatures, as well as oxidation and corrosion. For this reason, it is essential that they reflect precise design and production standards, in line with increasingly advanced technologies and materials.
To guarantee and maintain these criteria over time, aerospace fastening elements are usually made of:
Steel, endowed with high hardness and resistance;
Aluminum, an element that resists high temperatures and corrosion;
Titanium, durable and long-lasting.
The choice of which material to use is made based on the specific project or device to be created.
Use of Fasteners in the Aerospace Sector
The Role of Fasteners in the Railway Sector
One sector, perhaps more than any other, reflects the combination of ancient and modern just like fasteners. It is the railway sector, dating back to the early 1920s in Italy with the construction of the first tracks but today, increasingly modern and fast. Railway fasteners, even in this case, must meet specific criteria and standards because they are applied in two major areas:
Construction of the locomotion means
Construction of the infrastructure.
To comply with current regulations and thus guarantee increasingly high-performance and safe results, such fastening articles are subjected to specific treatments such as:
White zinc plating
Hot-dip galvanizing
Geomet treatment.
Many products are useful for railway application. Among all, we remember:
The variety of components available allows for the most suitable choice for the work, from the oldest railways to the latest generation high-speed trains, and thus guarantees high safety standards and cutting-edge systems.
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