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by Bernard Martin The history of screw threads highlights innovation, technology, and the pursuit of precision and standardization in engineering. We're going to take a tour of some history that begins with the ancient Greeks and Egyptians, moves through significant developments during the Renaissance, discusses modern standards and and culminates in a discussion of the potential directions of new applications and standards for screw threads. Grab a cup of coffee and read on. Ancient Beginnings Archimedes screw as a form of art by Tony Cragg at 's-Hertogenbosch in the Netherlands Greek and Egyptian InnovationsThe use of screw threads dates back to ancient civilizations, notably among the Greeks and Egyptians, who applied screw mechanisms in devices like the water screw for irrigation and olive oil presses. These early screws were primarily wooden and served as vital components in simplifying labor and enhancing the efficiency of agricultural and building projects. The genius of Archimedes, with the invention of the Archimedean screw, exemplifies early engineering innovation, showcasing the practical application of screw threads in lifting water. Greek Ingenuity: Archytas and Archimedes The tale begins in ancient Greece, a crucible of scientific thought and mechanical invention. It was here that Archytas of Tarentum, a philosopher, mathematician, and contemporary of Plato, is believed to have devised the first known screw mechanism between 428 BC-350 BC and used them in presses for olives and grapes. Although specific details of Archytas's contributions to screw technology are scarce, his work in understanding mechanics and motion undoubtedly paved the way for subsequent innovations. Archimedes, often celebrated for his mathematical genius and inventive prowess, is credited with the practical application of the screw principle in the form of the Archimedean screw. This ingenious device, consisting of a helical screw enclosed within a cylinder, was used to transfer water from low-lying bodies into irrigation ditches, proving invaluable for agriculture and the sustenance of civilizations. The Archimedean screw not only exemplifies the application of screw threads in ancient times but also highlights the Greeks' adeptness at leveraging simple mechanical principles for practical ends. Egyptian Mastery: Building a Civilization Parallel to Greek advancements, the ancient Egyptians demonstrated remarkable engineering capabilities, integrating screw mechanisms into their technology. Among their many innovations, the use of screw presses for extracting olive oil and wine stands out. These early applications of screw threads were pivotal in agricultural production and the economy, underlining the screw's role in enhancing efficiency and productivity in ancient societies. The construction of monumental structures like the pyramids further attests to the Egyptians' sophisticated use of technology. While direct evidence of screw threads in these constructions is speculative, the precision and ingenuity required suggest a deep understanding of mechanical principles akin to those employed in screw mechanisms. The Legacy of Ancient InnovationsThe contributions of ancient Greeks and Egyptians to the development of screw threads are more than historical footnotes; they represent the dawn of mechanical engineering and the human capacity for innovation. These early inventions laid the groundwork for countless technological advancements, illustrating the timeless value of observing, understanding, and applying natural principles. Renaissance RevivalPrecision and ApplicationThe Renaissance was a period of rediscovery and innovation, where the significance of precision in mechanical devices became increasingly recognized. This era saw the refinement of screw-cutting techniques and tools, marking a departure from the manual, less accurate methods of earlier times. The development of screw-cutting lathes during this period was instrumental in the manufacture of more precise and uniform screw threads, laying the groundwork for the advanced mechanical systems of the future.
Notable Contributors and Their Legacy The Age of Enlightenment and Beyond Antoine Thiout, a distinguished 18th-century French clockmaker, authored a seminal work in the field of horology that became a widely acclaimed reference throughout the late 1700s. His book, "Traité de l’horlogerie mechanique et Pratique," first published in 1741, offers a comprehensive overview of watch and clock components, the use of compasses, mechanics, pendulum construction, among other topics. What sets this treatise apart are the exceptional, fold-out illustrations it contains—detailed depictions of watch and clock parts along with guided instructions for crafting timepieces. These intricate plates not only embellish the work but also provide invaluable insight into the art and science of horology during that era. The Age of Enlightenment, a period distinguished by a fervent quest for knowledge and understanding, significantly impacted the development of mechanical engineering and manufacturing technologies. Two figures stand out for their contributions to the evolution of screw threads: Antoine Thiout and Ernst Lowenhertz. Their work not only represented breakthroughs in precision machining but also laid foundational principles for the standardization of mechanical components, which are still influential today. Antoine Thiout's Innovations with the Lead Screw Antoine Thiout, a French horologist and inventor, made a monumental advancement in the mid-18th century by introducing the lead screw into the lathe. This innovation was more than just a technical update; it was a paradigm shift in the manufacture of screw threads, enabling the creation of accurate and repeatable threads for the first time in history. The Mechanism and Impact The lead screw, essentially a long screw that controls the movement of the tool carriage in synchronization with the spindle, allowed for precise control over the cutting tool's movement along the axis of the workpiece. This meant that machinists could produce threads of consistent pitch and depth, a crucial requirement for the burgeoning fields of scientific instrumentation and mechanical engineering. Thiout's introduction of the lead screw enabled not just precision but also versatility in manufacturing, as it allowed for the production of a wide range of thread profiles and sizes. This capability was instrumental in the production of scientific instruments, where precision and reliability were paramount. The lead screw mechanism became a standard component of lathes, underpinning the development of modern machining and manufacturing processes. Ernst Lowenhertz and the Discovery of the Optimal Thread Angle Ernst Lowenhertz, working in Prussia in 1762, made a significant contribution to the standardization of Ernst Lowenhertz, in his groundbreaking work in Prussia in 1762, made a defining contribution to the field of mechanical engineering by identifying the optimal thread angle for screw threads to be 54° 45'. This discovery significantly advanced the standardization of screw threads, marrying strength with manufacturing efficiency in a manner previously unachieved. Lowenhertz's investigation into the optimal thread angle was not solely a matter of empirical experimentation; it was deeply rooted in theoretical analysis, notably leveraging an understanding of material stresses and Poisson's Ratio. Integrating Poisson's Ratio in Thread Angle Determination Poisson's Ratio, a fundamental principle that describes the ratio of transverse strain to axial strain in materials subjected to axial load, was critical to Lowenhertz's analysis. By applying this concept, Lowenhertz could more accurately predict how materials would behave under the stresses encountered by threaded joints. The selection of the 54° 45' thread angle was, therefore, not arbitrary but a calculated decision based on how materials deform under load. Understanding material deformation is crucial in designing threads, as it affects both the strength of the threaded connection and its reliability over time. Lowenhertz's application of Poisson's Ratio allowed him to determine that a 54° 45' angle offered an optimal balance: it maximized the contact area between the threads, thereby evenly distributing the forces and minimizing the stress concentrations that lead to material failure. This insight was instrumental in improving the longevity and durability of screw threads. The Rationale Behind the Angle The specific angle of 54° 45' facilitated not only an enhanced load-bearing capacity but also addressed manufacturing considerations. By understanding the material stresses and applying Poisson's Ratio, Lowenhertz ensured that the threads could be produced with the technology available at the time, without compromising on strength. This balance between theoretical ideals and practical feasibility was pivotal in the widespread adoption of his thread design. Moreover, the angle made the engagement and disengagement of threads smoother, an essential feature for the efficient operation of machinery. The Legacy of Lowenhertz's Work Lowenhertz's innovative use of theoretical principles like Poisson's Ratio in the practical problem of determining the optimal thread angle was a hallmark of the Age of Enlightenment's approach to scientific inquiry and mechanical design. His work laid the foundation for further standardization in screw thread design, emphasizing the critical role of material science and geometric considerations in engineering. The Legacy of Thiout and Lowenhertz The contributions of Ernst Lowenhertz, alongside those of contemporaries like Antoine Thiout, marked a significant leap forward in the precision and reliability of mechanical systems. Their work exemplifies the Enlightenment's spirit of exploration and rationality, showcasing how a deep understanding of fundamental scientific principles can drive technological progress and innovation. The principles established by Lowenhertz continue to influence modern manufacturing and engineering, underscoring the lasting impact of his contributions to the development of mechanical technology. Their contributions exemplify the Enlightenment's spirit of inquiry and improvement, demonstrating how thoughtful innovation can lead to advancements with lasting impact. The principles they established continue to underpin modern manufacturing and engineering, reflecting the enduring significance of their work in the development of mechanical technology. The Gribeauval System: Revolutionizing Military Engineering Gribeauval system field artillery gun barrels are shown. From left to right, they are 12-, 8-, and 4-pounders Jean-Baptiste Vaquette de Gribeauval, an esteemed French artillery officer and engineer, revolutionized artillery design and manufacturing in the late 18th century with his Gribeauval system. This innovative approach was born out of Gribeauval's experience in military engineering, including significant exposure to the advanced yet varied artillery practices of the Austrian army, juxtaposed with the inefficiencies he observed within the French military's artillery. Rethinking Artillery Production The crux of the Gribeauval system lay in its radical standardization of the manufacture and assembly of artillery equipment. Prior to this, French artillery components were produced in a bewildering array of sizes and designs, making maintenance and resupply overly complex and inefficient. Gribeauval's vision was to unify these disparate elements by standardizing the dimensions and designs of cannons, carriages, and ancillary components. This initiative aimed not only to enhance the mobility and efficiency of the French artillery but also to significantly ease maintenance efforts. A Pioneering Approach to Screw Threads A particularly transformative aspect of Gribeauval's system was its standardization of screw threads. Until then, the lack of uniformity in thread design across various components often led to compatibility issues, severely hampering the assembly and repair of artillery pieces. Gribeauval recognized that standardizing screw threads would facilitate the interchangeability of parts, a concept that was revolutionary at the time. By implementing a uniform thread system, Gribeauval ensured that all threaded components—ranging from the screws securing cannon barrels to the carriages, to the fastenings used in assembling the gun's aiming mechanisms—could be manufactured to a common standard. This not only streamlined the production process but also significantly reduced the logistical burden of maintaining and repairing artillery in the field. The ability to easily replace or interchange parts without the need for custom-fitting was a monumental step forward in military engineering. Legacy and Impact on Industrial Manufacturing The Gribeauval system's introduction of interchangeable parts, underpinned by the standardization of screw threads, had a profound impact beyond military applications. It demonstrated the practicality and efficiency of mass production techniques, paving the way for their adoption across various sectors of industry. The principles of standardization and interchangeability laid down by Gribeauval became cornerstones of the Industrial Revolution, fundamentally changing manufacturing processes around the world. The standardization of screw threads, in particular, emerged as a critical factor in the evolution of engineering and manufacturing, allowing for the widespread adoption of machinery and equipment with interchangeable components. This not only enhanced productivity and innovation within industries but also significantly reduced costs and improved the reliability of mechanical systems. In summary, Jean-Baptiste Vaquette de Gribeauval's system was a groundbreaking achievement that extended well beyond the realm of military engineering, influencing the development of manufacturing and industrial practices through its pioneering standardization of screw threads and the concept of interchangeable parts. This legacy of Gribeauval's innovation continues to underpin modern engineering and manufacturing to this day. Eli Whitney and Industrial Espionage First milling machine, Eli Whitney, about 1820 Eli Whitney, an American inventor best known for his invention of the cotton gin, is also a figure of intrigue in the history of industrial innovation, particularly for his alleged role in industrial espionage related to the development of screw threads. The Spy Story According to popular but not well-documented accounts, Whitney, in the late 18th century, undertook a secretive mission to England with the aim of learning British manufacturing secrets. Britain was the world leader in industrial processes at the time, and Whitney was keen to understand the advanced techniques employed in British factories. The story goes that Whitney managed to gain access to a British factory where he observed the use of taps and dies for threading, a technology that was then not widely used in the United States. Whitney is said to have either memorized or clandestinely obtained drawings and specifications for the tap and die set, and upon his return to the United States, he reproduced the tools. This act of espionage, whether entirely factual or embellished, highlights the lengths to which individuals and nations would go to secure technological advances during the industrial revolution. Impact on Whitney's Later Inventions The knowledge and tools Whitney acquired, according to the tale, played a crucial role in his future inventions, particularly in the development of the cotton gin and his contributions to the concept of interchangeable parts in manufacturing firearms. The precise threading tools enabled Whitney to produce components to exacting standards, facilitating the assembly and repair of machines with interchangeable parts. Whitney's actions, and the broader adoption of standardized screw threads and interchangeable parts, had a lasting impact on manufacturing. The ability to produce standardized, interchangeable components revolutionized production processes, making them more efficient and significantly lowering costs. Whitney's contributions to this field underscore the critical role of innovation—and sometimes, espionage—in driving technological progress. The Advent of Standards Whitworth thread form In the mid-19th century, Joseph Whitworth introduced a seminal development in the standardization of screw threads that would have a profound impact on manufacturing and engineering. Building on the work of predecessors like Ernst Lowenhertz, Whitworth made a critical adjustment to the thread angle, simplifying it from the precise 54° 45' determined by Lowenhertz to a more practical 55°. The Whitworth thread system was adopted by the British railways in 1841, and soon other industries followed suit. This adjustment, though seemingly minor, played a significant role in the advancement of thread standardization, leading to the establishment of the British Standard Whitworth (BSW) system, which became a cornerstone of industrial standards through the 20th and into the 21st century. Rationalization of the Thread Angle Whitworth's decision to adjust the thread angle to 55° was driven by considerations of manufacturing simplicity and efficiency. The slight increase in angle simplified the tooling required for thread cutting, making the production process more straightforward and less costly. This rationalization was crucial at a time when manufacturing industries were scaling up and seeking efficiencies in mass production. The 55° angle maintained the mechanical advantages of Lowenhertz's design, such as strength and ease of engagement, while streamlining manufacturing processes. Importance and Impact on Manufacturing Whitworth's simplification was important for several reasons. First, it demonstrated the value of standardization in engineering components, showing that a balance could be struck between optimal mechanical design and manufacturability. Second, by standardizing the thread angle, Whitworth facilitated the widespread adoption of interchangeable parts, a concept that was revolutionary for industrial manufacturing. This interchangeability was a key factor in the success of the industrial revolution, enabling the mass production of goods with consistent quality and compatibility. Foundation of the BSW Standards The adoption of Whitworth's 55° thread angle laid the groundwork for the British Standard Whitworth (BSW) system, one of the first standardized systems for screw threads. The BSW standards provided a uniform framework for the dimensions and thread angles of screws, bolts, and nuts, making it easier for industries across Britain and eventually the world to ensure compatibility and reliability of mechanical components. This standardization was instrumental in accelerating industrial development, facilitating the growth of engineering disciplines, and promoting international trade and cooperation. Legacy Through the 20th and 21st Century The legacy of Whitworth's standardization efforts, particularly the transition to a 55° thread angle, extends far beyond his time. The principles of the BSW system influenced subsequent standards, including the Unified Thread Standard (UTS) and the International Organization for Standardization (ISO) metric thread standards. These later standards have continued to evolve, but they all share a common lineage that traces back to Whitworth's pioneering work. His contributions have enabled industries to achieve higher levels of precision, efficiency, and quality in manufacturing, underpinning the development of modern technology and infrastructure. Whitworth's adjustment of the thread angle to 55° and the establishment of the BSW standards were pivotal in shaping the landscape of manufacturing and engineering. By prioritizing both practicality in production and the need for mechanical efficiency, Whitworth set a precedent for standardization that has supported technological advancement and global industrialization for over a century. Whitworth threads, which featured radiused roots, exhibit significantly enhanced fatigue strength and were less prone to cracking in the sharp corners at the roots of Vee Form threads. However, the complexity of manufacturing tools for cutting these rounded surfaces is greater compared to those used for creating the National Standard's flattened roots and crests which we will talk about next. Specialized Thread Standards World War I and the ABC StandardsWorld War I was a catalyst for significant advancements in industrial standardization, particularly in the domain of screw thread standards. The war's demands for rapid production and repair of military machinery and equipment underscored the critical need for uniformity in manufacturing processes among the Allies. This period saw the emergence of the American British Canadian (ABC) Council of Industry, which played a pivotal role in adopting a unified approach to screw thread standardization, notably the adoption of a 60-degree thread angle. The groundwork for screw thread norms in the United States was laid by William Sellers in 1864, who proposed a 60-degree thread angle among other specifications, later known as the Sellers thread. The Franklin Institute of Philadelphia backed this proposal, and by 1868, it was approved for use in the U.S. naval service.
Adoption of a 60° Thread Angle The decision to adopt a 60° thread angle over the previously common 55° angle which was the Whitworth standard, was driven by the need for a more simplified, versatile, and robust standard that could be easily adopted by manufacturers across different countries. The 60° angle was found to offer a good balance between strength and ease of manufacture, making it suitable for the diverse range of applications encountered in military hardware. This angle facilitated the creation of threads that were both strong and easy to engage and disengage, which was crucial for the maintenance and repair of equipment in the field. The ABC Simple Fit Guide and Standardized Pitches The ABC Council further introduced a simple fit guide and standardized pitches for each screw diameter. It used the the rounded root form of the Whitworth to improve fatigue performance and the 60° flank angle and flat crests from Sellers, therby streamlining the production and interchangeability of threaded components. This standardization was essential for accelerating production times, reducing waste, and ensuring that components from different suppliers could be used interchangeably without the need for custom fitting. The Unified National Thread Standard and Post-War Developments The basic profile of all UTS threads is the same as that of all ISO metric screw threads. Only the commonly used values for Dmaj and P differ between the two standards The establishment of the Unified National Thread Standard (UNTS) and the adoption of metric standards post-World War II represent pivotal moments in the quest for global uniformity in manufacturing. These developments, aimed at simplifying international trade and enhancing the dissemination of technology and goods, underscored the critical importance of standardized components in the industrial landscape. The journey towards this uniformity, characterized by significant milestones and strategic shifts, reflects the evolving needs of industrial efficiency and technological innovation. From World War I to the Unified National Thread Standard The seeds for the Unified National Thread Standard were sown during the exigencies of World War I, where the American British Canadian (ABC) Council's efforts to standardize screw threads highlighted the strategic advantages of interoperability and manufacturing efficiency. This period underscored the necessity for a unified approach to component manufacturing, setting the stage for the development of a comprehensive national standard in the subsequent decades. In the 1920s, under the auspices of the American Standards Association (ASA), the principles established by the ABC Council during the war years were refined and expanded, culminating in the creation of the Unified National Thread Standard. This initiative was driven by the burgeoning demand for industrial efficiency and the interoperability of components, especially within the rapidly growing automotive and manufacturing sectors in the United States. The Formation of ANSI and the Introduction of UNC and UNF The geopolitical and technological landscape of the late 1950s, particularly marked by the Soviet Union's launch of Sputnik, prompted a reassessment of the United States' technological and industrial strategies. This event, known as the Sputnik crisis, catalyzed a renewed focus on technological and industrial competitiveness. In response, the American Standards Association was reorganized into the American National Standards Institute (ANSI) in 1958, a move that underscored the burgeoning importance of standardization in bolstering national security and fostering technological advancement. Amidst this backdrop of strategic realignment, the thread standards underwent further refinement, leading to the differentiation into Unified National Coarse (UNC) and Unified National Fine (UNF) thread forms. This bifurcation was a strategic decision aimed at addressing the nuanced requirements of various industrial applications. The coarser UNC threads were designed for general applications, prioritizing ease of use and manufacturing. Conversely, the finer UNF threads were tailored for applications demanding higher tensile strength and precision, showcasing an ongoing evolution and specialization in screw thread technology to meet specific engineering needs. The Rationale for UNC and UNF Threads Replica of Sputnik 1 in the Museum of Space and Missile Technology (Saint Petersburg) The Formation of ANSI and the Introduction of UNC and UNF The launch of Sputnik by the Soviet Union in 1957 triggered the Sputnik crisis, leading to a renewed emphasis on technological and industrial competitiveness in the United States. In response, the American Standards Association was reorganized into the American National Standards Institute (ANSI) in 1958, reinforcing the importance of standards in national security and technological advancement. This period also saw the rationalization of thread standards into two primary forms: the Unified National Coarse (UNC) and Unified National Fine (UNF) thread forms. The rationale behind creating these two standards was to cater to the diverse needs of various applications. UNC threads, being coarser, were ideal for general applications where ease of use and manufacturing were prioritized. Coarse-threaded bolts, cut deeper into materials, have a smaller root diameter, making them less strong but suitable for gripping soft materials like cast iron and aluminum in rougher applications. In contrast, In contrast, UNF fine-threaded fasteners boast superior strength and vibration resistance, fitting for harder materials. Automotive and aircraft studs exemplify this duality, with coarse threads at one end for better grip in softer engine metals and fine threads at the other for stronger hold in steel nuts. ChatGPT Coarse-threaded bolts, cut deeper into materials, have a smaller root diameter, making them less strong but suitable for gripping soft materials like cast iron and aluminum in rougher applications. In contrast, fine-threaded fasteners boast superior strength and vibration resistance, fitting for harder materials. Automotive and aircraft studs exemplify this duality, with coarse threads at one end for better grip in softer engine metals and fine threads at the other for stronger hold in steel nuts. The creation of UNC and UNF standards was a strategic response to the varied demands of different applications, with UNC threads catering to ease of use in general applications, and UNF threads providing the required strength and precision for more demanding tasks. The Future Standards of Screw Threads image source via Volume Graphics. Developers of leading software for the analysis and visualization of industrial 3D computed tomography data. Click on the image to link to their website The landscape of screw thread technology is poised for transformative advancements, significantly influenced by progress in materials science, manufacturing techniques, digital technologies, and the specific needs of niche applications. These developments promise to redefine the capabilities and applications of screw threads across various industries.
Here are some areas where we can expect to see significant progress:
These anticipated advancements in screw thread technology are driven by the imperative for higher performance, greater efficiency, and more sustainable manufacturing practices. As industries evolve, the requirements for threaded fasteners will also advance, spurring ongoing innovation in this fundamental aspect of mechanical design. The detailed history of screw threads from ancient innovations to contemporary standards reveals a continuous thread of ingenuity and the pursuit of precision and efficiency. Each period brought forth advancements that built upon previous knowledge, reflecting humanity's relentless drive to improve and standardize the fundamental components that underpin mechanical and engineering achievements.
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written, compiled and edited by Bernard Martin  The basic profile of all UTS threads is the same as that of all ISO metric screw threads. Only the commonly used values for Dmaj and P differ between the two standards. Class of fit for a cutting tap refers to the specific tolerance or fit that is desired between the threads of the tap and the threads of the hole it is being used to create. In other words, it defines how tightly or loosely the threads should mesh together. The class of fit is typically expressed using a combination of letters and numbers. The most commonly used standards for class of fit are the Unified Thread Standard (UTS) and the ISO metric thread standard. In the UTS, the class of fit is denoted by a combination of a letter and a number, such as 2B, 3A, etc. In the ISO metric thread standard, it is represented by a combination of a letter and a number, such as 6g, 4h, etc. For cutting taps, the class of fit is usually specified based on the intended application and the level of precision required. The class of fit can affect factors like the ease of assembly, the strength of the threaded connection, and the ability to engage the threads smoothly during tapping. A classification system exists for ease of manufacture and interchangeability of fabricated threaded items. Most, but certainly not all, threaded items are made to a UTS classification standard. This system is analogous to the fits used with assembled parts.
The letter suffix "A" or "B" denotes whether the threads are external or internal, respectively. Classes 1A, 2A, 3A apply to external threads; Classes 1B, 2B, 3B apply to internal threads Here are some common classes of fit for cutting taps:
The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch. For diameters smaller than 1⁄4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.
This number pair is optionally followed by the letters UNC, UNF or UNEF (Unified) if the diameter-pitch combination is from the coarse, fine, or extra fineseries, and may also be followed by a tolerance class. Example: #6-32 UNC 2B (major diameter: 0.1380 inch, pitch: 32 tpi) Browne & Co has been appointed as Regaional Managers for Regal Cutting Tools. They will be responsibilve for distributor and technical support for the Kentucky, Ohio, and Western Pennsylvania market areas.  Regal Cutting Tools has been manufacturing world-class cutting tools since 1955 Regal offers a high performance SuperTuf series of taps for the demanding difficult to machine materials. Regal also manufactures special taps from blanks with as little as 24 hour notice.
According to Dave Browne, President of Browne & Co, "Regal Cutting Tools. is a well established and trusted brand within the metalcutting industry. Their full line of taps as well as their tap specials capabilities really compliment our product mix and fills an area we have pretty deep experience in but didn't have a product to recommend. We're really looking forward to working with our customers and running these tools!" This is Part 2 of our series on Carbide taps. Be sure to check out Part 1 if you missed it: Carbide Taps: A Practical User’s Guide to When, What, How and Why Carbide taps have a lot of advantages, especially when you’re cutting very abrasive materials. The absolute best choice for tapping glass-filled polycarbonates, space age alloys, nonferrous materials, cast iron, and a range of other exotic materials, their anti-friction qualities lead to a longer tool life.
Standard Screw Thread Insert Taps S.T.I. (Screw Thread Insert) Taps are special taps for helical coil wire screw thread inserts, which provide positive means for protecting and strengthening tapped threads in any material. Typically used on softer abrasive materials, these taps create more accurate thread forms than other standard taps. When you need to be precise, these carbide taps are the best choice. STI taps are correctly sized to produce an internal thread that accommodates a helical coil wire screw thread insert. The insert, in turn, will accept a screw thread of the nominal size and pitch at final assembly. Screw thread inserts provide stronger tapped threads (stronger assemblies) due to a more balanced distribution of loads throughout the length of thread engagement. Thread Forming Tap  Roll Taps (aka, Thread forming taps, Form taps0 offer improved thread quality and strength due to the fluteless design, and therefore allows for greater fastener strength in the threaded product. This tap does not cut, so it is “chipless,” and therefore will not cause a chip problem. This is why thread forming, over thread cutting, eliminates costly and time-consuming chip clean-up and disposal. Thread forming taps are fluteless and include lubrication grooves. Not intended for general applications, they work by displacing the metal without removing it. Because of this, they are ideal for chip removal in blind holes. Roll Thread Forming Taps Features
Carbide Insert Taps A cost-efficient solution, only the cutting portion of insert taps is made from carbide. Their HSS body is able to absorb vibration and account for their lack of rigidity. If you’re considering testing the waters with carbide taps, insert taps are a great option. It's a very economical way to utilize the benefits of carbide with solid carbide cutting face inserts meticulously brazed to a H.S.S. tap body. Carbide Insert Tap Features
Highly abrasive materials like cast iron, polymers, glass filled polycarbonates, and some cast aluminum are called “hard” materials for a reason. They’re hard to machine, hard on tool life and hard on production cycle times. How do you overcome the difficulties of making parts out of challenging raw stock? By using a tool that’s even tougher. Consider a change from steel taps to carbide taps. When to Use Carbide Taps
We offer carbide taps in UN and Metric sizes as well as straight and NPT/F Pipe and STI Standards. A wide range of styles and features are available, including straight flute, spiral flute, spiral point, and forming taps. For increased performance and life, we can customize tools with a full line of surface coatings such as TiN, TiCN, and TiALN. How to Use Carbide TapsMachining with carbide does come with some “do’s and don’t”. Hand tapping is generally not recommended. Rigid tapping and spot-on alignment are critical to avoid breakage. Not to worry, however. Modern CNC equipment is ideally suited for carbide applications. Here’s some additional tips. Coolant holes through the taps are an option for flushing chips out of the holes on the most difficult materials like some of the tougher stainless steels and space-age alloys. Carbide STI (Screw Thread Insert) tapping of these materials has become commonplace in the aeronautical and aerospace industries. The Why of Carbide Taps CARB-I-SERT® CARBIDE INSERT TAPS Although initially more expensive than HSS taps, significant savings can be realized, especially in long-run jobs. Higher cutting speeds, greater tool life, and reduced downtime from fewer tooling changes translate into reduced machining costs.
An alternative to costly larger sizes is our line of CarbISert® Taps. Solid carbide cutting surfaces are bonded onto a high-speed steel body to provide the best of both worlds; durability of carbide with the “forgiveness” of a steel body and shank. So, don’t let difficult materials give you a “hard” time. Contact us anytime and put our carbide taps to work for you. Watch for Part 2 of this series on carbide taps! Coming in August 2021: The Different Types of Carbide Taps and When to Use Them  Almost a year ago, Allen Benjamin, which has been a part of North American Tool, was purchased by GWS Tool Group. GWS Tool Group is a US-based, vertically integrated manufacturer of highly engineered custom, standard, and modified standard cutting tools, primarily servicing the aerospace and defense, power generation, automotive and medical sectors. GWS Tool Group has acquired multiple businesses in the course of its growth which now serves as the respective manufacturing divisions for the Company. Just because there is a new owner, doesn't mean that the quality of an Allen Benjamin Tap has changed! If you’re in the market for high tensile strength carbide taps and metric taps, we can assure you that you’re in the right place. Not only is Allen Benjamin a leading supplier of the industry’s most durable, longest lasting carbide taps, we offer our customers the convenience of ordering online. In this day and age, we believe that quick access and top-notch customer services are critical. In today’s post, we’re going to look at why it is beneficial to order your carbide taps from Allen Benjamin. Quality Allen Benjamin carbide taps are highly efficient when tapping abrasive metals such as aluminum, non-ferrous metals, and exotic materials. With a much higher tensile strength than standard taps, their high-quality carbide taps can withstand the rigorous demands of your application. Selection Allen Benjamin offers a staggering range of carbide taps, metric taps, HSSE taps, tapping fluid, extensions, and more. If it’s taps that you are looking for, you can be confident that they’ve got them and have them ready for delivery. Service Allen Benjamin guarantees that all of their products will be the absolute best quality, within standard tolerances and dimensions, and consistent with application specifications. If their goods don’t meet your needs, you can contact us for a return authorization. At Allen Benjamin, they take pride in offering the industry’s best taps. But, more importantly, they aim to provide our customers with access to a simpler, faster way to order their operation’s critical parts, supplies, and components. If you’ve been searching for a supplier that will meet your needs and rise to meet your challenges contact us today!   How can you optimize a tap's chamfer based on your application? Although North American Tool/ GWS stocks many common special taps with standard chamfer lengths, they can design and manufacture a special tap for your application. Optimizing the chamfer results in, longer tap life, reduced tapping torque, better finish, and make the difference between success and failure. As most of you know, the chamfer is the tapered section on the front of the tap. It includes the length, angle, radial relief, and point diameter. As the tap rotates and advances forward, each succeeding chamfered tooth enters the drilled hole and takes deeper and deeper cuts until the first full thread on the tap completes producing a full thread in the part. The balance of the tap’s threads within the length beyond the chamfer, do not do any cutting and just goes for the ride.
Increasing the total number of chamfered teeth cutting, can increase tap life exponentially. The example above shows that a standard plug chamfer (3 to 5 threads) length, so on a 4 fluted tap, it will range between 12 to 20 cutting teeth. Because North American Tool/ GWS understands more is better, they make it a point to manufacture our taps with a chamfer length closer to maximum length, in this case, 5 threads. This is also true for the other standard chamfer lengths Bottom, Semi Bottom, and Taper. Although more is better, you may be limited to the length of chamfer due to the job requirements. We should also note that the incomplete threads created and left in the part by the chamfer are not too full thread height and will cause assembly interference, therefore they are not considered part of the required thread length. As for manufactured specials, knowing your application requirements is necessary for us to design a tap that optimizes performance. For chamfer design, North American Tool/ GWS would need to know, tap drill size, tap drill depth, and full thread length requirement. Knowing the tap drill size allows us to grind a chamfer with a point diameter that permits the tap to start cutting within the first half thread of entry. Because there are many factors that go into determining a tap drill size, there can be a relatively wide range of diameters. If the chamfer point diameter is smaller than the tap drill diameter, then the tap may not start cutting until the second chamfer tooth or beyond. Using the same 4 flute, plug tap from the example above, in an application with a tap drill size larger than the chamfer point diameter, such that the tap does not start cutting till the 2nd chamfer tooth, will have a reduction in cutting teeth by 6 (1.5 threads X 4 flutes), or 30%. If the application is such that only a bottom chamfer (1 to 2 threads) can be used, and it is ground to the maximum length of 2 threads it will result in a reduction of cutting teeth from 8 (2 threads X 4 flutes) to 6 (1.5 threads X 4 flutes) or 75%. Knowing the tap drill depth and full thread length requirement also allows us to design the maximum length chamfer for your application. This may take into consideration the overspin of the machine spindle, or room at the bottom of a blind hole so the tap does not run into any chips that may have made their way to the bottom.  Although the information presented may be confusing, hopefully we have explained the importance of the chamfer, and the many considerations that go into its proper design.
So, if you are ready to increase tap life, reduced tapping torque, improve the finish, and make the difference between success and failure, give us a call with your application requirements.  If you’re cutting extremely abrasive material, we’re confident that you’ve already investigated the benefits of carbide taps. Whether you’re tapping cast aluminum, nonferrous materials, polymers, cast iron, or any number of other materials, carbide taps offer better edge wear resistance and, more importantly, help to reduce downtime and increase profitability. As an ISO 9001:2008 registered manufacturer, Allen Benjamin is absolutely committed to offering the best taps on the market. In today’s post, we’re going to look at a few of the benefits of using our carbide and high-performance taps. Stronger Ideal for very abrasive metals, carbide taps have a much higher tensile strength than standard taps. Because of this, they offer a longer tool life and work to reduce production costs. Better performance Due to their ability to increase tool life, carbide taps have a positive effect on your operation’s performance. Helping you to reduce maintenance and – by extension – downtime, they allow your staff to focus on more productive, more profitable tasks. Cost-effective While the initial cost may be higher than standard taps, carbide taps are far more cost-efficient in the long run. Their extended tool life results in fewer replacements which, of course, leads to less reorders and money saved over time. At Allen Benjamin, we are steadfastly dedicated to our customers’ productivity. Always aiming to offer products that are capable of reducing maintenance, increasing uptime, and improving profitability, we strive to act as a convenient, responsive supplier of high-quality carbide taps. Whether you’re a small, local manufacturer in need of a handful of taps or a large, multi-national operation looking to place a large order, you can be confident that we can help. If you have any questions about our products, we encourage you to reach out to us today to discuss your needs! Carbide Taps From Allen BenjaminAllen Benjamin’s carbide taps provide a substantial increase in performance and tool life over HSS – or high speed steel – taps. As a result, our customers experience longer tool life and, due to this, reduced production costs that help to contribute to higher profits and a more efficient line.
Choose from six rings to maximize tool life and improve thread quality. Here’s the key to selection:  These tools are stocked standards. Fractional sizes are available from #0-80 up though 1”-8 and Metric sizes from M2.5 x 0.45 through M20 x 2.5. To compete for the gold with your customers, choose High Performance with Allen Benjamin Color-Ring Taps. edited by Bernard Martin Getting a good understanding of the definitions of the parts of a tap will help you to better understand the functions of tap designs. Special thanks to North American Tool for letting us share their short and simple explanations!  ALLOWANCE Minimum clearance between two mating parts; the prescribed variations from the basic size. ANGLE OF THREAD The angle included between the sides of the thread measured in an axial plane. AXIS The imaginary straight line that forms the longitudinal centerline of the tool or threaded part. BACK TAPER A gradual decrease in the diameter of the thread form on a tap from the chamfered end of the land towards the back which creates a slight radial relief in the threads. BASE OF THREAD The bottom section of the thread; the greatest section between the two adjacent roots. BASIC SIZE The theoretical or nominal standard size from which all variations are derived by application of allowances and tolerances. CHAMFER The tapering of the threads at the front end of each land of a tap by cutting away and relieving the crest of the first few teeth to distribute the cutting action over several teeth; Taper taps are chamfered 7-10 threads; plug tapsare chamfered 3-5 threads; semi-bottoming (or modified bottoming) taps are chamfered 2-2.5 threads; bottom-ing taps are chamfered 1-2 threads; taper pipe taps are chamfered 2-3.5 threads.  CHAMFER RELIEF The gradual decrease in land height from cutting edge to heel on the chamfered portion, to provide clearance for the cutting action as the tap advances. CREST The top surface joining the two sides or flanks of the thread; the crest of an external thread is at its major diameter, while the crest of an internal thread is at its minor diameter. CUTTING FACE The leading side of the land in the direction of cutting rotation on which the chip forms. FLUTE The longitudinal channels formed in a tap to create cutting edges on the thread profile, and to provide chip spaces and cutting fluid passages. HEEL The edge of the land opposite the cutting edge. HEIGHT OF THREAD The distance, measured radially, between the crest and the base of a thread. HELIX ANGLE The angle made by the advance of the thread as it wraps around an imaginary cylinder. HOOK The undercut on the face of the teeth.  HOOK ANGLE The inclination of a concave cutting face, usually specified either as Chordal Hook or Tangential Hook.
INTERRUPTED THREAD TAP A tap having an odd number of lands with alternate teeth along the thread helix removed. In some cases alternate teeth are removed only for a portion of the thread length. LAND The part of the tap body which remains after the flutes are cut, and on which the threads are finally ground. The threaded section between the flutes of a tap. LEAD The axial distance a tap will advance along its axis in one revolution. On a single start, the lead and the pitch are identical; on a double start, the lead is twice the pitch. MAJOR DIAMETER Commonly known as the “outside diameter.” It is the largest diameter of the thread. MINOR DIAMETER Commonly known as the “root diameter.” It is the small-est diameter of the thread. PERCENT OF THREAD One-half the difference between the basic major diameter and the actual minor diameter of an internal thread, divided by the basic thread height, expressed as a percentage.  PITCH The distance from any point on a screw thread to a cor-responding point on the next thread, measured parallel to the axis and on the same side of the axis. The pitch equals one divided by the number of threads per inch. PITCH DIAMETER On a straight thread, the pitch diameter is the diameter of the imaginary co-axial cylinder...the surface of which would pass through the thread profiles at such points as to make the width of the groove equal to one-half of the basic pitch. On a perfect thread this occurs at the point where the widths of the thread and groove are equal. On a taper thread, the pitch diameter at a given position on the thread axis is the diameter of the pitch cone at that position.  RAKE
The angular relationship of the straight cutting face of a tooth with respect to a radial line through the crest of the tooth at the cutting edge.
RELIEF (or Thread Relief) The removal of metal from behind the cutting edge to provide clearance and reduce friction between the part being threaded and the threaded land. ROOT The bottom surface joining the sides of two adjacent threads, and is identical with or immediately adjacent to the cylinder or cone from which the thread projects. SPIRAL FLUTE A flute with uniform axial lead in a spiral path around the axis of a tap. SPIRAL POINT The angular fluting in the cutting face of the land at the chamfered end; formed at an angle with respect to the tap axis of opposite hand to that of rotation. Its length is usually greater than the chamfer length and its angle with respect to the tap axis is usually made great enough to direct the chips ahead of the taps cutting action. STRAIGHT FLUTE A flute that forms a cutting edge lying in an axial plane. TOLERANCE In producing a tap to given specifications, tolerance is: (a.) the total permissible variation of a size; (b.) the difference between the limits of size. |
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