One of the primary challenges faced by the sheet metal working industry is minimizing downtime between completing one batch of parts and starting the next. VICLA has addressed this issue by developing an innovative tool storage solution tailored to press brake tooling: ATC Automatic Tool Changer. VICLA ATC Tool Changer: Efficient Tool Storage, Loading, and Unloading Designed to streamline the interface between the press brakes and the storage system, the VICLA Automatic Tool Changer ensures quick, effortless, and safe storage, loading, and unloading of all sizes of punches and dies. Key Features of the Automatic Tool Changer Modular Design: Easily customizable to fit any press brake configuration and usage requirements. Scalability: Expand storage capacity by adding additional modules as needed. Versatile Options: Available in double input models and XXL sizes for large and heavy-duty press brakes. Comprehensive Tool Management: Efficiently store and manage not only punches and dies but also special tools like hemming tables. Key aspects of automatic load and unload of punches and dies This system is customisable and designed to measure according to client requirements; it reduces setup by 4 or 5 times compared to the ordinary manual operation and it automatically performs even the most complex equipment, managing tool sets up to 1-3/4” V opening and rod holding tools. The upper tools can also be rotated 180 degrees. It also allows the use of Promecam or WILA clamping systems. Automation covers everything, including upstream operations. One of the more interesting aspects is programming by the technical office: the CAD/CAM system processes the three-dimensional file, creates the best bending cycle and sends the program to the machine that is automatically equipped, recalling the bending sequence directly on the numerical control. All tooling and machining data are automatically saved at the end of the work and exported to management for a 4.0 key data analysis. Advantages: Reduction of set-up times Increase of productivity Customizable configuration Versatile and automated programming Simple and intuitive use Handling of complex setting Setup two press brakes at the same time VICLA ATC system - Single or Twin – is designed to automate and speed-up the setups for efficiently producing small batch sizes. The system combines one or two hybrid press brakes with an automatic tool changer, allowing for multiple tooling setups, reducing setup times by 4 or 5 times compared to the ordinary manual operation. The main element of the system is a compact shuttle that serves as robotic tool changer that places the tool sets, up to 1-3/4” V opening, in the clamping systems of the upper and lower beams. This shuttle retrieves and replaces tools in the tool magazine, which can store up to 197 ft. of dies and punches. The tooling can be used in manual or robotic setups. The upper tools can also be rotated 180 degrees. Offline programming One of the many advantages of the VICLA automatic tool changer is the offline programming capability. The CAD / CAM system processes the three-dimensional file, creates the best bending sequence and sends the program to the machine, which is automatically equipped, and calls-up the bending sequence directly on the numerical control screen. All tooling and processing data are automatically saved at the end of the job and exported to the management system for data analysis. Need More Information? Whether you're seeking to optimize your press brake tool management or have specific questions, don't hesitate to contact us. Download our brochure or submit an online request for a quotation.
Springback is a frequent challenge encountered in sheet metal bending: it occurs when a bent piece of metal partially returns to its original shape after the bending force is released. This phenomenon is a result of the material's inherent elasticity. Why Does Springback Happen? Internal Stress: When a material is bent, its internal structure is stressed. Some parts of the material are compressed, while others are stretched. Elastic Recovery: When the bending force is removed, the compressed and stretched areas try to return to their original state, causing the material to partially straighten What's happening inside a bend When you bend a piece of metal, the outer part stretches (tensile stress), while the inner part compresses. There's a neutral layer where there's neither tension nor compression. The fibers in the outer stretched layers tend to pull the bend back towards its original shape, causing springback. Tensile Test To understand this better, scientists do a tensile test. They pull a piece of material until it breaks. This test shows how the material stretches and at what point it breaks. The tensile test, although simple, provides fundamental data for understanding the mechanical characteristics offered by a given material. To perform the test, a special hydraulic machine is used that has housings or clamps in which the ends of the specimen are inserted, which can have different shapes and sections but are standardized. This kind of reverse press has the characteristic of exerting a tensile stress, rather than a compressive one, and causes a tension in the specimen until the material yields and subsequently breaks. The entire test cycle is not random, but is carried out slowly and gradually, recording two fundamental quantities: the amount of pressure exerted; the percentage elongation of the specimen. These two measurements are translated into a graph that traces the progress of the deformation and rupture of the specimen in real time. What the stress-strain curve tells us: Elastic region (A-B): the material can return to its original shape if the load is removed. Yield point (B): the material starts to deform permanently. Plastic region (B-D): the material is permanently deformed. Fracture point (D): the material breaks What does it have to do with springback in metal bending? Returning to bending, we can understand that the zone around the neutral plane is the one that has undergone the least stress and has therefore remained in the elastic condition of the material: it is exactly where the fibers directly responsible for elastic recovery reside. The peripheral zones, on the other hand, are irreparably yielded and contribute to the stability of the deformation. We will see later the strong connection that exists between the neutral plane and the issue of sheet metal developments. Calculating Springback Accurately calculating springback requires understanding several factors: Modulus of Elasticity (MOE): Also known as Young's modulus, it measures a material's stiffness and resistance to deformation. Yield Strength: The point at which a material begins to deform plastically. K-factor: A multiplier that determines the neutral axis location within a bend. Read our full guide and use our online calculator for k-factor Inside Bend Radius: The radius of the inner curve of the bend. Material Thickness: The thickness of the sheet metal. Bend Angle: The desired angle of the bend. Luckly, modern press brakes, such as VICLA bending brakes, uses NC to predict and compensate for springback. Some advanced machines produced by VICLA provide devices that compensate for springback in real time. Factors Affecting Springback in metal bending: Yield Strength: Stronger materials exhibit more springback. Bend Radius: Sharper radii generally lead to less springback. Die Opening: Wider die openings in air forming can increase springback. Material Thickness: The relationship between bend radius and thickness impacts springback. Overcome Springback Springback depends on many variables related to the sheet metal, and each material reacts differently. In some high-strength steels, the springback is so pronounced that special equipment is required. So how do you compensate for springback? While coining was once a common method to address springback, it's generally not considered the most effective or efficient option today due to potential drawbacks. Bottom bending offers greater control over the bend angle compared to other methods, but it can be challenging due to the high tonnage requirements. Air forming, especially when paired with a modern CNC press brake, is a relatively stable process. However, variations within the same batch of sheet metal can still impact springback. Factors like thickness, grain direction, and tensile strength play a significant role. Achieving Perfect Bends For precise bending in applications where springback is critical, angle compensation feedback mechanisms can be employed. These systems utilize sensors, cameras, or lasers to monitor springback during the bending process and make real-time adjustments to ensure accurate results. Angle Control for Managing Springback Angle control systems are essential for effectively managing springback in sheet metal bending. These advanced technologies accurately measure and correct deviations in bend angles, ensuring precise and consistent results. By continuously monitoring the bending process, angle control systems can detect and compensate for springback in real-time. This eliminates the need for manual adjustments and reduces the risk of errors. Additionally, these systems can store historical data on springback behavior, allowing for optimized process settings and improved part quality. VICLA's angle control system is a state-of-the-art technology designed to deliver exceptional precision and performance in sheet metal bending. With its advanced capabilities, VICLA's system ensures consistent bend angles and minimizes the effects of springback. One of the key advantages of VICLA's angle control is its ability to learn and adapt. The system stores historical data on springback behavior, allowing it to continually refine its adjustments and optimize the bending process for specific materials and applications. Conclusion By understanding and addressing the factors that contribute to springback, you can significantly improve the accuracy and efficiency of your sheet metal bending processes. Implementing strategies like overbending, angle compensation, and proper tooling selection will help you achieve consistent results and minimize waste.
Hydraulic press brakes, known for their precision and power, utilize oil cylinders to control the bending process. While offering superior performance, they can be complex to maintain and may have higher operating costs. CNC hydraulic press brakes automate many functions, improving efficiency and accuracy. Synchronized hydraulic press brakes, a more advanced version such as VICLA .Smart model, use two independent cylinders for precise control and greater versatility. Components of an hydraulic press brake Hydraulic cylinders: these are the muscles of the machine. They generate the necessary force to push the bending ram down onto the metal sheet, creating the desired shape. Operator controls: think of these as the machine's steering wheel. They allow the operator to fine-tune the bending process by adjusting settings like the angle and pressure. Hydraulic fluid: this fluid acts as the machine's lifeblood, transmitting pressure from the cylinders to the bending ram. Die set: the die and punch are the tools that shape the metal. They're like cookie cutters, determining the final form of the bent piece. How Hydraulic Press Brakes Work The hydraulic press brake operates by harnessing the force of hydraulic fluid, which is controlled by modern computer technology. When the operator initiates the bending process, hydraulic pumps generate pressure. This pressure is transmitted through the hydraulic system, causing the ram to move vertically. The ram then applies force to the metal sheet, pressing it against the die to create the desired bend. The operator controls the ram's speed, position, and force using CNC machines or computer controls. This allows for precise adjustments and ensures high-quality bends. How to operate hydraulic press brake When an operator activates the foot pedal to make a bend, the ram descends to a predetermined point. In reality, the bending cycle consists of several distinct phases, each with its specific function and name. Operator Input The operator sets the desired bending parameters, such as the angle, depth, and material type. Ram Descent The machine's ram moves downward towards the sheet metal. Bending As the ram descends, it presses the metal against the die, forming the desired shape. Dwell Time The ram remains in position for a brief period to ensure the bend is complete. Ram Ascent The ram moves back up to its starting position. Are hydraulic press brakes accurate? Hydraulic centering, also known as automatic crowning, is a system used to maintain consistent bend angles across the entire length of a workpiece. It compensates for the natural deflection of the press brake bed, ensuring precise and uniform bends. How does hydraulic crowning system work? Hydraulic centering is a system that uses high-pressure cylinders strategically placed within the press brake bed. These cylinders counteract the bed's natural deflection during bending, ensuring a consistent and parallel alignment between the punch and die. This, in turn, results in a workpiece with a uniform bend from center to side. The numerical control system can accurately predict the necessary force to apply to the hydraulic cylinders based on factors like the workpiece's dimensions, material, and the press brake's structure. This ensures optimal performance and precise bending results. Evolution of cnc hydraulic press brake Hybrid press brakes represent the pinnacle of press brake technology, offering significant advancements over traditional synchronized hydraulic press brakes. This innovative approach combines the best aspects of different systems, delivering exceptional results in terms of precision, repeatability, energy efficiency, and cost-effectiveness. Key benefits of hybrid press brakes include: Microscopic precision: ensures consistent and accurate bends. Energy efficiency: up to 78% energy savings compared to traditional hydraulic press brakes. Versatility: handles a wider range of applications than electric press brakes. Hybrid press brakes demonstrate the evolution of press brake technology, offering superior performance and efficiency while maintaining the versatility of traditional hydraulic press brakes. What can you create with an hydraulic press brake? Hydraulic press brakes are versatile tools used across numerous industries to transform sheet metal into various forms. Their precision, efficiency, and power make them indispensable in shaping components for everything from automobiles to buildings. The Automotive Industry Body panels: hydraulic press brakes form the intricate curves of car and truck bodies. Chassis components: frames, brackets, and other structural elements are shaped using these machines. Internal structures: dashboards, consoles, and other interior components are also formed with hydraulic press brakes. The Aerospace Industry Aircraft parts: wings, fuselages, and landing gear are shaped with precision using hydraulic press brakes. Structural components: internal frames and supports are fabricated to exacting standards. The Construction Industry Structural elements: beams, columns, and other components for buildings and bridges are formed using hydraulic press brakes. Metal roofing and wall panels: these machines create the intricate shapes needed for modern construction. HVAC components: ducts, vents, and other parts are fabricated using hydraulic press brakes. The Shipbuilding Industry Hull formation: large sheets of metal are bent and shaped to create the hull of ships. Internal structures: hydraulic press brakes form various internal components for ships. Tips for Choosing the Right Hydraulic Press Brake A common mistake when purchasing a hydraulic press brake is to focus solely on the brand name before considering your specific needs. While well-known brands often have a good reputation, it's crucial to prioritize your production requirements. Here are some key factors to consider. If you are interested in this topic, don't miss to read our utlimate guide on choosing the right press brake Workpiece Dimensions Length and Thickness Determine the maximum length and thickness of the material you'll be bending. For instance, if you're primarily working with 3mm thick carbon steel sheets up to 2500mm long, an 80-ton press brake is sufficient. Material Type Consider the different types of metals you'll be working with. Stainless steel, for example, requires significantly more bending force compared to carbon steel. Production Needs Batch Size If you have large production runs, a more powerful press brake might be necessary. For smaller batches, a smaller, more compact machine could be more suitable. Complexity of Bends The complexity of the bends you need to produce will also influence your choice. Features and Options Automation Consider the level of automation you require. Some press brakes offer features like automatic tool changing, which can increase productivity. VICLA's ATC Automatic Tool Changer reduces setup times compared to manual labor. It can manages multiple stations, different tools and can automatically setup up to two press brakes at the same time. Control System The control system should be user-friendly and offer the necessary programming capabilities for your specific applications. Read our guide which explains the different type of cnc press brakes and how they work. Hydraulic Press Break Cost and Budget The cost of a press brake is a significant factor to consider. However, it's essential to evaluate the machine's capabilities and features in relation to its price. A higher investment may be justified if it leads to increased productivity, improved accuracy, or reduced operating costs over time. Ask yourself: does the machine's cost align with its features and capabilities? Will the machine provide a positive return on investment through increased efficiency or cost savings? Hydraulic press brake vs electric press brake: differences and advantages Hydraulic and electric press brakes are two common methods for bending sheet metal, each with its own set of advantages and disadvantages. Hydraulic press brakes rely on hydraulic fluid to power the ram, generating substantial force for bending operations. While known for their smooth and powerful action, hydraulic systems can be less energy-efficient and exhibit slower response times compared to their electric counterparts. Electric press brakes, conversely, utilize electric motors to drive the ram, resulting in faster response times, greater precision, and lower energy consumption. Furthermore, the absence of hydraulic fluid in electric press brakes makes them generally quieter and more environmentally friendly. Who are the top press brake manufacturers? The top press brake manufacturers include AMADA, Trumpf, Bystronic, LVD, Cincinnati and VICLA. These companies are known for innovation, quality, and customer service in sheet metal processing. Each offers sheet metal working machinery with features enhancing precision, efficiency, and productivity. While many brands focuses on a wide range of sheet metal machineries, VICLA, an Italian manufaturer of press brakes, have decided to focus only on cnc press brakes, offering tailored-made solutions for sheet metal bending. Products include hydraulic press brakes, hybrid press brakes and the soon-to-launch electric press brake. VICLA has its own vendor in USA, with two offices located on the West and East coast, providing commercial and technical services. Vendor Support and Warranty Consider the vendor's after-sales support and warranty. A reputable vendor offers installation, training, and maintenance. A solid warranty provides peace of mind. VICLA is an Italian leading hydraulic press brake manufacturer known for quality and innovation. Our customizable CNC hydraulic press brakes offer a wide range of sizes and configurations. Contact us!
Sheet metal bending, a pivotal process in metal forming that dates back to ancient times, involves manipulating sheet metal into desired shapes through the application of force. This technique has evolved significantly with technological advancements, encompassing a range of methods like air bending, V bending, and U bending, each suited to specific applications. Metal bending is a complex process that requires careful consideration of various factors, including material properties, press brakes, tooling, and process parameters. The ability to consistently achieve accurate and high-quality bends is crucial in many industries. Today, commonly used machines for sheet metal bending include press brakes, rotary bending tools, and roll bending equipment, showcasing the versatility and adaptability of this process. These machines have evolved to offer greater precision, efficiency, and automation, allowing for the production of complex components in large volumes. Table of Contents History of Sheet Metal Bending Types of Sheet Metal Bending Importance of Sheet Metal Bending in Manufacturing Sheet Metal Bending Process, Design and Planning Common Materials Used in Sheet Metal Bending Sheet Metal Bending Machines Understanding Sheet Metal Bend Allowance and K-Factor Challenges and Solutions in Sheet Metal Bending Evolution of sheet metal forming Today's modern press brakes are equipped with sophisticated CNC systems, offering enhanced precision and efficiency. While the basic mechanical concept remains the same – bringing a punch to a matrix – the internal mechanisms and electronics have undergone substantial advancements. This evolution has transformed press brakes into high-tech machines capable of producing complex bends with greater accuracy and repeatability. Why Is Sheet Metal Bending Essential in Manufacturing? Sheet metal bending is a cornerstone of manufacturing, transforming flat metal sheets into essential components across various industries. From automotive and aerospace to consumer electronics and construction, its versatility and importance are undeniable. Material selection is crucial in sheet metal fabrication, as it directly impacts the strength, durability, workability, and appearance of the final product. Understanding the composition, characteristics, and interactions of various materials with the press brake is essential for accurate project calculations. Beyond Steel: Exploring Diverse Sheet Metal Options Here's a list of common materials used in sheet metal bending: Steel: The most widely used material due to its strength, durability, and versatility. Aluminum: Lightweight, corrosion-resistant, and easy to work with. Stainless steel: Offers excellent corrosion resistance and formability. Copper: Known for its electrical and thermal conductivity, often used in decorative applications. Brass: A copper-zinc alloy with a golden appearance and good workability. Titanium: Highly durable and lightweight, often used in aerospace and medical applications. Cor-Ten steel: A weathering steel with self-protecting properties. The choice of material depends on factors such as the required mechanical properties, corrosion resistance, cost, and the specific application. Material Composition Key Characteristics Common Applications Steel Iron and carbon alloys High strength, durability, versatility, cost-effective Automotive, construction, appliances Unalloyed Steels Iron and carbon Varying levels of hardness based on carbon content General-purpose applications Alloyed Steels Iron, carbon, and other elements Enhanced properties like corrosion resistance, heat resistance, and specific mechanical characteristics Stainless steel, Cor-Ten steel Stainless Steel Chromium, nickel, and often molybdenum Excellent corrosion resistance, formability, durability Food processing, marine, medical, architectural 300 Series Stainless Steel 304 (18/10), 316 High corrosion resistance, formability Commercial kitchens, appliances, food processing 400 Series Stainless Steel 430, 410 Good corrosion resistance, mechanical properties Appliance panels, cutting tools, industrial equipment Cor-Ten Steel Weathering steel Self-protecting from corrosion, high tensile strength Outdoor structures, architectural elements Aluminum Lightweight, corrosion-resistant, easily processed Aerospace, automotive, consumer electronics Copper High electrical and thermal conductivity, corrosion resistance Electrical wiring, heat exchangers, decorative elements Brass Copper and zinc Malleable, corrosion-resistant, attractive appearance Decorative components, musical instruments, plumbing fixtures Titanium Lightweight, highly durable, corrosion-resistant Aerospace, medical, military Want to learn more about sheet metal materials and their applications? Read our comprehensive guide on how to choose the right material for the bending process Principle of Sheet metal Bending Process Sheet metal bending involves a series of steps, beginning with design and planning. Factors such as material type, thickness, and desired bend angles are considered to select the appropriate sheet metal and bending method. The process then involves material preparation, alignment, and the actual bending operation. Finally, the finished product is inspected and verified to ensure it meets the design specifications. Types of sheet metal bending methods A deformation process is a technological process that involves modifying the dimensions of a material through the application of controlled external stresses. In the case of sheet metal, deformation processes can be divided into five main groups. Air bending It is the typical deformation of press brakes. It represents the most versatile processing and involves the use of a die with a V-shaped groove and a punch. The points of contact with the sheet metal are three: 1) vertex of the punch; 2) left vertex of the die; 3) right vertex of the die. The versatility of three-point bending lies in the possibility of working on small and discontinuous batches together with large productions with a practically infinite range of thicknesses; in fact, conceptually, there is no actual limit to the thickness in bending. In fact, assuming that it is possible to have a machine with adequate performance and by widening the size of the die, it is possible to bend any thickness of sheet metal. Sheet metal bending is carried out by vertically approaching the tools up to the desired height and identified by the numerical control of the machine. Behind this simple concept, many technological and design solutions have been developed by manufacturers over time. Some of these are now completely outdated in favor of others that guarantee greater precision, speed, safety and lower environmental impact. Pros Versatility: Suitable for various metal types and thicknesses. Reduced tool wear: Less contact with the die reduces wear and extends tool life. Flexibility: Allows for a wide range of bend angles with a single set of tools Cons Less precision: The bend angle can be influenced by the material’s springback. Dependence on material properties: Variations in metal thickness or strength can affect bend consistency. Forming or coining Through a wide range of possibilities (such as deep drawing, hydroforming, etc.), this type of processing involves the use of dies that give a specific shape to the sheet metal and are designed exclusively for this purpose. It is a process that is not particularly versatile but that guarantees great repeatability. Forming is in fact the most adopted solution by companies that need to produce large volumes. Pros: High Precision: Yields exact bend angles with minimal springback. Consistent Results: Ideal for repetitive, high-volume production with uniform quality. Clean Edges: Produces sharp, well-defined bends. Cons: Tool Stress: Exerts significant pressure on tools, leading to potential wear. Material Limitation: Less effective for very thick or hard materials. Higher Cost: Often more expensive due to increased tooling demands. Folding It involves the deformation of long strips of sheet metal through their forced passage through a long series of rollers that gradually modify their shape. Folding requires a dedicated system, such as folding machines, often of large dimensions, but allows obtaining complex profiles thanks to the possibility of adding further processing during the process, such as cutting, punching, welding, threading and much more. Panel bending It is carried out by applying a lateral force through a moving blade, which deforms the panel until the desired shape is reached. Its use is dedicated to thin thicknesses, typically up to a maximum of 3 mm. Panel benders are very complex machines and relatively recent, having been born around the 1970s; they guarantee high productivity and versatility in the face of a high initial investment. What is the desired outcome of this bending operation? When we ask, 'What am I trying to achieve with this bend?', we're diving into the heart of sheet metal forming: managing variables. Several factors influence a metal’s ability to bend without breaking or losing its structural integrity Every bend has specific requirements, including desired angle, radius, and surface finish. These requirements, combined with the properties of the sheet metal itself, the tooling used, and the machine settings, all contribute to the final outcome. Understanding these variables is essential for producing consistent, high-quality bends. Here a list of the 5 most important factors that determine the bendability of metal. For the full list, please refer to this table. Material Composition and Finishings Any type of surface treatment or pattern on the sheet metal can make bending more challenging. Perforations or raised patterns on the sheet metal can make bending even more difficult. The uneven distribution of material along the bend line (i.e., the area that will be deformed) creates asymmetrical stresses that cause the part to slip during the bending process, making it particularly difficult to achieve a correct flange length. The same inconsistency is also reflected in the bend angles, which vary continuously, making it difficult to standardize the process. This means that when the material has an uneven surface (like perforations or textures), it causes uneven forces during bending. This can make the part slip, leading to inaccurate bend angles and inconsistent flange lengths. How to solve it One possible way to counteract this problem to a significant extent is to install a wider die. Bending with wider dies means that the deformation occurs over a larger area and is therefore gentler. However, such a measure is not always sufficient and is completely useless in ensuring consistent flange lengths. Using a wider die can help distribute the forces more evenly, but it won't solve the problem completely, especially when there are significant differences in the material thickness on either side of the bend line. Unfortunately, in the presence of holes, raised patterns, or other functional features, there are asymmetries between one side and the other side of the bend line that make the use of a wider die useless. Features like holes or raised patterns create uneven stresses that can overcome the holding force of the die, causing the part to slip. These asymmetries during deformation create asymmetrical stresses, often greater than the clamping force. This causes the sheets to slide in search of an equilibrium, and the most evident consequence of this variability factor is inconsistent and varying flange lengths. The uneven stresses caused by the features on the material can lead to the sheet metal sliding during bending, resulting in inconsistent flange lengths. Thickness Variation Thickness variation is generally the most common variable in bending operations and is also quite common in plain, unfinished sheet metal. Why? Simply put, the processes used to produce sheet metal, especially for thicker gauges, cannot guarantee absolute precision. In fact, each sheet exhibits dimensional deviations, which, although within the expected tolerances at the time of purchase, impact the consistency of angles during bending. The thicker the material, the more noticeable the problem becomes. A decrease in the actual thickness of the workpiece leads to an increase in the angle α. The reason for this annoying issue is purely geometric and, unlike other variable factors, it doesn't affect the earlier stages of the production process. The maximum downward travel of the upper beam coincides with the lowest point reached by the punch inside the die and is called the 'Lower Dead Point' (LDP). The CNC controls identify the LDP using an internal algorithm that calculates it based on the following data: sheet thickness, material, tool height, and desired angle (angle α). The CNC machine converts the desired bend angle into a specific movement of the punch. The accuracy of this conversion depends on how advanced the machine's software is and the overall quality of the machine. Even a small difference in thickness can cause a significant change in the bend angle, especially for angles close to 90 degrees. These variations might seem insignificant in earlier stages like cutting or nesting, but can have a big impact on the final bend angle. Grain Direction The orientation of the metal’s grain can significantly impact its bendability. This variable is also known as anisotropy, and it is a physical property that affects how sheet metal behaves when bent in the longitudinal or transverse direction. This characteristic is imparted to the raw material during the rolling process, particularly in cold rolling. The rolling process causes three dimensional changes in the starting semi-finished product according to the following proportions: Along the length, very significantly; Along the width, to a medium-low extent; Along the thickness, very slightly and gradually. This means that the internal fibers of the material are forced to follow the direction of the most modified dimension and, therefore, are arranged perpendicular to the rolling mill rollers. This causes the sheet metal to respond differently to bending when done transversely or parallel to the rolling direction. An anisotropic material, in fact, has different mechanical strengths depending on the orientation. For example, alloys like AISI 430 stainless steel and aluminum exhibit significant anisotropy. This variable affects the consistency of bend angles and, in some cases, even the developments. The bend radius, in fact, is the element that most affects standardization: the stronger a material is, the larger the naturally occurring inner radius will be. The more yielding a material is, that is, the less resistant, the smaller the bend radius will be. For this reason, the same sheet, which guarantees its maximum mechanical performance when bent transversely to the rolling direction, generates two different radii. Temperature The sole environmental variable that significantly influences the sheet metal bending process is temperature. While temperature fluctuations are often overlooked in controlled environments, they can have a noticeable impact on both the bending machine and the sheet metal itself. For example, extreme temperature changes, such as those experienced on very hot or cold days, can affect the machine's hydraulic system and the material's properties. Similarly, when working with freshly cut metal that is still at a different temperature than the ambient environment, temperature variations can introduce inconsistencies in the bending process. Even in highly automated production lines, temperature remains a critical factor to consider. In bending machines, temperature fluctuations can affect the machine's performance from the moment it is turned on to after numerous bending cycles. What are Critical Design Considerations for Sheet Metal Bending? Effective sheet metal bending requires careful design considerations. To achieve the desired outcome without compromising the material's integrity, it's essential to focus on the following key aspects: Material Selection: choose a material that suits the project's functional and aesthetic requirements, considering its bendability. Bend Radius: ensure the bend radius is appropriate for the material thickness to prevent cracking or deformation. Grain Direction: align the bend line with the metal grain to reduce the risk of cracking. Bend Angle Accuracy: consider the material's springback characteristics to achieve the desired bend angle. Hole Placement: avoid placing holes near the bend line to prevent distortion or weakening. Edge Condition: ensure smooth edges on the sheet metal to avoid irregularities in the bend. Calculating Bend Allowance and K-factor The K factor is a crucial parameter in sheet metal bending, but it can be tricky to determine, as it depends on factors like material, thickness, inner radius, and bend angle. The k-factor is fundamental to designing precise sheet metal products. It allows you to anticipate the bend deduction for a large variety of angles without having to rely on a chart. There are numerous ways to explain it, but let's just say the k-factor is the percentage that reflects how the neutral axis move toward the inside surface during the bending process. In other words, the k-factor is nothing more than a multiplier that can give you an accurate value for the relocated neutral axis. And if you know the bend allowance, you can extract the k-factor from it. Once you know the k-factor, you can use it to predict the bend allowance for various angles. Read our guide to understand more about k-factor. What is sheet metal bend allowance? Bend allowance is a critical value in sheet metal fabrication. It refers to the additional length of material required to account for the stretching that occurs when a sheet metal part is bent. Essentially, it's the extra length you need to add to a flat sheet to achieve the desired bend angle. The neutral fiber is an imaginary line within the material that experiences neither tension nor compression during bending. It's along this line that the material neither stretches nor compresses. Bend allowance is the extra length you need to account for when bending a piece of metal, to ensure that the final part is the correct size. Why is bend allowance important? Accurate dimensions: without the correct bend allowance, your finished part will be too short. Consistent results: a well-calculated bend allowance ensures that all parts are identical. Reduced waste: by accurately calculating the bend allowance, you can minimize material waste. Using Software for Calculations of Bend Allowance and K-Factor You can use our online calculator to accurately calculating k factor and sheet metal bend allowance. Troubleshooting Common Sheet Metal Bending Issues Understanding and addressing common sheet metal bending problems can significantly improve the quality and efficiency of the fabrication process. Here are some frequent issues and potential solutions: Springback: to prevent the material from returning to its original shape after bending, slightly overbend or use a material with a lower yield strength. Cracking: avoid bending the metal beyond its elastic limit. Using a proper bend radius and annealing the material can help prevent cracking. Warping: to avoid uneven stresses and prevent warping, ensure uniform thickness and use symmetric bending techniques. This can include punctures and vent curls. If you eager to learn how to avoid them, read our dedicated guide on how to deal with puntures and vent curls in sheet metal bending. Scratches or Surface Marks: protect the material with films and maintain clean tooling to prevent surface damage. Inaccurate Bend Angles: regular maintenance and calibration of the bending machine are crucial to ensure accurate angles.
The choice of the right material is fundamental for any sheet metal fabrication project. Understanding the composition and characteristics of these materials, how they interact with the press brake, and the variables of the sheet metal itself, is essential for accurate development calculations. Different materials offer unique characteristics that can significantly influence the strength, durability, workability, and aesthetic appearance of the final product. Steel Throughout history, steel has always been employed in a highly versatile manner. This material has been indispensable for technological innovation worldwide. In fact, without its availability and low cost, the Industrial Revolution would not have been possible. Over time, steel production techniques have been perfected. When discussing steel, it's useful to distinguish between two main families: Unalloyed steels: Composed of iron and carbon alloys. Alloyed steels: Alloys containing elements in addition to iron and carbon. Beyond the presence of elements, there are different types of steel based on the percentage of carbon present. In general, the higher the carbon content, the greater the hardness. When referring to mild or hard steels, we're talking about the carbon concentration. Generally, steel can be classified into these categories: Extra mild: 0.5-0.25% carbon Mild: 0.15 – 0.25% carbon Semi-mild: 0.25 – 0.40% carbon Semi-hard: 0.40 – 0.60% carbon Hard: 0.60% - 0.70% carbon Very hard: 0.70% - 0.80% carbon Extra hard: 0.80 – 0.85% carbon Alloyed Steels We've mentioned that alloyed steels are metals that mix other elements besides iron and carbon. One of the most famous is undoubtedly stainless steel. Stainless Steel Stainless steel is composed of a high percentage of chromium, which makes the material highly resistant to corrosion and temperature; chromium also provides great malleability, making stainless steel a material used in countless applications. In press braking, various types of stainless steel are used, each with specific characteristics that make them suitable for particular applications. The most commonly used types of stainless steel are: 300 Series Stainless Steel Stainless Steel 304: This is the most common and versatile type of stainless steel and is also known as 18/10 stainless steel due to the percentages of chromium and nickel present in the alloy. It's known for its excellent corrosion resistance and formability. This material is often used in applications requiring high corrosion resistance, such as commercial kitchens, appliances, and food processing equipment. Stainless Steel 316: In addition to nickel and chromium, it also contains molybdenum, which further improves corrosion resistance, particularly against saline and chemical environments. It's widely used in marine, chemical, pharmaceutical, and medical applications where the environment is particularly aggressive. 400 Series Stainless Steel Stainless Steel 430: This is a type of ferritic steel with good corrosion resistance and good mechanical properties. It's often used for internal applications such as appliance panels and architectural cladding. However, compared to the 300 series, it has lower corrosion resistance and lower malleability. Stainless Steel 410: It offers a good balance between corrosion resistance and hardness. It's used for applications requiring high wear resistance and moderate corrosion resistance, such as cutting tools, blades, and industrial equipment. Cor-Ten Steel Cor-Ten steel, also known as weathering steel, is a special alloy with a brownish-red color. The name COR-TEN comes from the combination of corrosion resistance and tensile strength, highlighting its main characteristics of corrosion resistance and tensile strength. The primary property of Cor-Ten steel is its rare and unique ability to self-protect naturally from corrosion, an oxidative reaction that responds to environmental stresses and leads to the development of a surface oxide patina that, if scratched or removed, constantly regenerates over time. Aluminum Aluminum is another highly popular material in sheet metal fabrication due to its lightweight nature, corrosion resistance, and ease of processing. It finds applications across a broad spectrum, from aerospace to automotive and even household appliances. Aluminum can be anodized to further enhance its corrosion resistance and aesthetic appeal. Copper Copper is renowned for its exceptional electrical and thermal conductivity, making it perfect for electrical and heating applications. It also exhibits good corrosion resistance and can develop a protective patina, lending it a unique and appealing appearance. However, copper is relatively expensive and often used in specialized applications. Brass Brass, an alloy of copper and zinc, is valued for its ease of processing, corrosion resistance, and golden appearance. It's widely used in decorative components, musical instruments, and plumbing fixtures. Its malleability allows for the creation of intricate and precise details, making it ideal for precision work. Titanium Titanium is a highly durable and lightweight material known for its exceptional corrosion resistance and ability to maintain its structural integrity even at high temperatures. It's employed in industries demanding superior performance, such as aerospace, medical, and military. The downside is that titanium is expensive and requires specialized processing techniques. The choice of material for sheet metal fabrication depends on a variety of factors, including the desired mechanical properties, corrosion resistance, cost, and the specific application. Each material offers unique advantages and can significantly influence the production process and the performance of the final product. Understanding the characteristics and interactions of these materials is essential for successful sheet metal fabrication projects.
Stainless steel's unique properties, such as its corrosion resistance, which we explain in detail in this guide to materials in sheet metal working, make it a popular choice. Stainless steel is used in industries ranging from food processing to construction and medical equipment. However, working with stainless steel in the sheet metal bending process presents a number of unique challenges. To understand these challenges and how companies are overcoming them, we interviewed two specialists in stainless steel fabrication. The Challenges of Bending Stainless Steel Stainless steel parts are prized for their high resistance to corrosion, hygiene, and visually appealing finishes. However, these same qualities can create problems during processing, particularly bending. Stainless steel sheets aren't your typical flat sheet, says Davide Chinellato, Production Manager at Inox Piave di San Fior. They often undergo various processes that can lead to deformation and thickness variations. The key is achieving consistent, uniform bends along the entire length of the piece. Beyond bend quality, processing speed is crucial. Today's press brakes need to be extremely fast while maintaining safety compliance, Chinellato adds. This was a challenge in the past, as safety features often slowed production. VICLA machines, however, deliver complete safety without sacrificing performance. Stainless steel's properties necessitate meticulous handling to avoid visible defects in the finished product. Marco Nervi, owner of C.L.A. LAVORAZIONE INOX, a company specializing in raw stainless steel machining, emphasizes this point: For instance, bending requires a perfectly straight and continuous bend throughout the entire piece. If the bending machine's force isn't consistent, you might end up with a slightly open or closed bend. Choosing the Right Bending Machine Selecting the right press brake is critical for achieving flawless parts on the first try. Companies managing numerous orders with departments working in sync require machinery that guarantees precision, repeatability, and reliability. Inox Piave, for example, opted for a unique press brake configuration to handle their one-of-a-kind parts. The machine, developed over a year, features a special backguage explains Chinellato. Essentially, it has a single crossbeam for general movement of the stops, plus four independent stops for customized adjustments. The Advantages of Hybrid Bending Machines Both companies chose a hybrid press brake due to its numerous benefits. Firstly, it offers consistent repeatability thanks to a compact system with reduced piping and a direct drive connection between the pump and motor. Secondly, there's speed. Hybrid press brakes leverage cutting-edge technology to deliver high thrust. The system combines an electric axis with a hydraulic clutch and a brushless electric motor, providing both high force and fast travel speeds. Finally, hybrid machines offer greater versatility compared to all-electric models. As Chinellato explains, For the bending we do, an all-electric option wouldn't deliver the necessary performance. That's another reason we chose VICLA's hybrid technology. Selecting the Right Tools Cost is another crucial factor when working with stainless steel, as Nervi explains: Material costs have risen in recent years, especially in the first half of 2022 when finding materials was difficult. This, combined with the material's delicate nature, makes waste reduction essential. Even minor marks can render a stainless steel component unusable, particularly in applications like furniture where aesthetics are paramount. Materials like AISI 304 stainless steel, iron, galvanized steel, copper, brass, aluminum (including diamond plate and painted varieties) all require meticulous handling to avoid visible defects. Choosing the right bending machine is crucial, but so is using tools that won't damage the material, such as protective films placed between the sheet metal and the die. We have written a guide that illustrates the main types of dies and punches most used in bending. The K-Factor in Sheet Metal Bending The K-factor is a critical aspect in sheet metal processing, including stainless steel. It's essential for achieving accurate bends. The K-factor represents the ratio of the material thickness to the neutral radius, directly impacting the final bend result. For a deeper dive into the K-factor and its influence on stainless steel processing, please refer to our article on the sheet metal K-factor.
When we talk about tandem press brakes, we refer to a particular configuration that involves the connection of two machines into one, but there are also solutions that combine three bending machines (tridem) or 4 bending machines (quadrem). In this type of configuration, the machines can have the same length and the same nominal bending power or different lengths and nominal bending powers can be provided. What are the characteristics to consider when choosing a tandem configuration? Let's find out together in this complete guide. What are tandem press brakes? When two press brakes are used in tandem, a single CNC controls both machines. However, each machine can also be used independently for added flexibility. What are tandem bending machines used for? To bend long profiles, it is not necessary to have a large bending machine. Sometimes it is enough - and much more beneficial - to choose a tandem configuration, because it allows for greater versatility and productivity. Specifically, tandem bending machines can be used in synchronised or single mode. In the first case, both machines can be programmed by the numerical control of the master machine, which sends the signals to the secondary machine, allowing synchronized management with a single CNC. It is crucial that both machines are perfectly calibrated, as any problem on one machine will affect the operation of both. In any case, machine builders already prepare the optimal configuration of the machines during assembly, so if the operator follows all the instructions given during installation, it is very difficult for problems to arise in the future. In the case of separate use of the machines, each machine is independent, equipped with its own photocells and a safety guard. With this solution it is possible to carry out different processes in each machine, with the advantage of optimizing production in the best possible way. In fact, many metalwork fabrication, in addition to the bending of heavy and long profiles, supports the bending of shorter pieces. Moving a huge machine to bend smaller profiles would be costly in terms of time, energy and productivity. With a tandem setup, however, you can easily switch to single mode and operate each machine completely autonomously. So that's one of the great advantages of the tandem setup! We'll talk about the other benefits - and limitations - in a moment, but first we'll focus on some equally important aspects. What processes can be done? Most of the bending that requires a tandem configuration concerns long sheets that require high powers. The processed products belong to the most varied sectors, including: industrial bodywork, trailers, agricultural equipment, aircraft parts, modular spaces and storage solutions. Most tandem bending machines have deeper recess dimensions (e.g. around 1000 mm) in order to allow more agile bending of wide profiles. To enable this, machine tool manufacturers such as VICLA design a larger, thicker and more solid structure that can compensate for the increased stresses that result from having a larger groove. Another interesting aspect is that, compared to a large bending machine, tandem bending machines generally do not need a pit for the lower bench housing What are the characteristics to consider when choosing a tandem? When choosing a tandem configuration, it is important to consider the bending force: it is widely believed that using two bending machines in combination allows you to double the bending force at every point of the machine, but this is a mistake. The total force, given by the combination of the force of each machine, applies only in the case of bending along the entire length. Let's take a concrete example. Let's take two bending machines of 4 meters and 250 tons each. In a tandem configuration, the total force is equal to 500 tons, but only if you are working on a profile that requires the entire length. On the other hand, in the case of a shorter profile, for example less than 4 meters, the total power will be 250 tons! Another aspect to evaluate is the configuration: tandem bending machines allow you to have almost the same customizations as a single bending machine, with one caveat: while, for example, it is possible to have a different number of axes for each machine, the configuration of the stomp and the bench, for obvious reasons, will necessarily have to be identical in both machines. Here is a list of the customizations you can do: Oversized recess Increased stroke Larger opening Intermediate heights Clamps for all types of tools Sheet metal escorts Motorized front supports What are the advantages of tandem compared to using a single machine with the same length and power? When choosing whether to have a tandem, it is important to consider the following advantages: Flexibility: we have repeatedly specified the great versatility of a tandem, but it is worth repeating it once again. Such a configuration allows two machines to be used together or separately, with the great advantage that a workshop does not need to equip itself with additional machines. It also allows you to adapt to business changes effectively, always ensuring future business options. Last, but not least, is the speed of execution: thanks to the reduced size, the bending machines configured in tandem are more streamlined in movements than a larger bending machine and this allows to obtain a fast work cycle. Lower risks: buying a tandem allows you to halve the risks compared to buying a large bending machine, which will be more exposed to the risk of production stoppages. In a tandem, on the other hand, it will still be possible to produce parts on the working machine. Lower ancillary costs: Before purchasing, it is always important to evaluate all the costs related to the new project. How do transportation costs differ for one large machine compared to two smaller machines? Will special permits be required? Will additional foundation preparation work be required for one type of configuration over another? Understanding all the associated costs is the only way to accurately calculate your return on investment. What are the limitations of a tandem? We often talk about the benefits, but little about the limitations. Let's look at some factors that can influence the decision to buy a tandem: We have already said that the versatility of tandems consists in being able to bend long pieces without having to equip themselves with imposing machines that require more space and additional bending at the foundations. However, it's worth noting that a tandem setup still has limitations. One of them is related to the recess: although it is possible to increase the depth, it could still interfere with the bending of certain parts. Another consideration is the cost of the machine. Depending on the case, buying a large car can prove to be more expensive than choosing a tandem, however, the opposite is also true. In fact, a tandem consists of two machines and therefore each component is doubled (two CNCs, 4 cylinders, etc.). This does not mean that a tandem is less convenient than a single car, but it is certainly one of the many aspects to consider when buying. Now let's see what the other criteria are to consider before buying a machine. What criteria should be adopted when purchasing a new machine? Before proceeding with the purchase of a tandem or a large bending machine, it is essential to consider all the variables at play, first and foremost your production needs. What are the processes you need to do? How much do they cost you? What is the level of sustainability in continuing to process the parts through the current production process? These are fundamental questions to pay close attention to. How to achieve higher productivity and save costs? What are the markets that offer the latest products? What are the changes in the production field in recent years? Buying tandems seems like a serious financial solution. Start with a clear estimate of the status of your work and get the answers to questions about how to increase the productivity of your operations and get the most profit possible. Our consultants at your disposal Would you like personalized advice to find the right machine for you? Contact us now.
The ever-increasing demand for skilled pressbrake operators, who possess both practical know-how and a deep understanding of the theoretical aspects of bending, has solidified our commitment to providing comprehensive training opportunities. In collaboration with an Italian school, we are proud to offer a unique theoretical/practical BENDING CLASS. The program attracted a diverse group of participants, including experienced, as well as young PB operators eager to learn, and drawing department personnel seeking to enhance their knowledge. The enthusiasm for learning and the need for technical expertise were palpable throughout the course. Many companies have recognized the importance of investing in training to unlock the full potential of their workforce and technology. By empowering their employees with the necessary skills and knowledge, they can achieve a significant competitive advantage. The ongoing industrial change requires making the production cycle increasingly efficient, keeping production costs low without compromising quality and safety. Factors such as the growing demand for product customization, on one hand, and the difficulty of finding qualified labor, on the other, are pushing companies to reorganize their production departments to remain competitive. One of the fundamental elements on which companies are trying to act to contrast the shortage of labor is to enhance internal resources by training, stimulating, and retaining them. Training plays a key role because it allows us to acquire an awareness of the difficulties and the most practical aspects of bending thanks to which it is possible to make the process more streamlined and solve many problems upstream of production. A highly skilled press brake operator or fabricator who possesses a deep understanding of both the practical and theoretical aspects of sheet metal working is an invaluable asset to any company. In fact, a qualified and adequately trained operator will play a key role in making the production cycle increasingly efficient, contributing to increasing the quality level in the repetitiveness of the processing processes. A second interesting aspect related to personnel training is its flexibility. Companies are increasingly aware that to improve the efficiency of the production chain, synergy is needed between the technical office and the production department. In fact, the technical office must have precise information on the characteristics and limits of press brakes in order to design and draw efficiently, avoiding errors and waste. It happens too often, in fact, that the technical office develops developments with tolerances that are too hard, if not impossible to achieve considering the equipment (press brake and tools) in the bending department. Knowing the theoretical bases behind the sheet metal forming process can help designers and draftsmen to have a complete overview of all the necessary elements in the design and drawing of parts. It is precisely to encourage the sharing of knowledge that at VICLA we have chosen to move in two directions: on the one hand, by organizing training days, full of detailed diagrams and valuable insights that stimulate lively debates; on the other hand, by creating a bending manual – as for now, available only in Italian - which summarizes the theoretical and operational bases of sheet metal working. The manual contains numerous tips and practical advice to take press bending to its maximum possible performance, as well as an in-depth overview of the evolution of press brakes and new technological solutions to improve the quality of finished products. For 10 years now, the machine tool industry has been witnessing an incredible revolution, says Marcello Ballacchino, owner of VICLA together with his partner Corrado Nucci. I am referring to the automation of processes, the advent of robotics and the development of machines with a high energy coefficient. And then we must not forget the great theme of the Digital Factory. This new way of conceiving production is projecting the entire sector into the future. Hence, VICLA's mission to continue to look ahead, to anticipate requests and meet the needs of customers. The Bending Day was a valuable opportunity to share our passion for sheet metal working and to forge stronger relationships with our customers We can't wait to replicate this experience!
Sheet metal bending often represents the bottleneck of the entire production process, because sheet metal, which is a living material, can take on infinite shapes and sizes and this, sometimes, is the cause of little-known and complex problems to solve. It must be said that, sometimes, problems do not arise in front of the machine, but very often are caused by an upstream error in the technical office. It is for this reason that you should learn to identify sources of error early on and correct them upstream, when it is still possible to intervene in the entire bending process. What are the most common problems when bending sheet metal? Simplifying, we can distinguish between two categories: punctures and vent curls. For each, there are different approaches you can take to eliminate or limit the problem. Here's a summary of what we'll be talking about: Punctures near the bend line Partial punctures Pre-drilling with smaller diameter Vent Cuts Reducing the width of the matrix Changing the Folding Mode Using tangential bend dies Vent Curls Vent Cuts Bending Mode Changes Tangential bend dies A book would not be enough to describe in detail every single point and the possibilities of solution. Today we will limit ourselves to talking about sheet metal drilling and what are the first two solutions you can adopt. We'll be delving into the rest of the game in the coming weeks. Drilling near the bend line Punctures in the vicinity of the bend line are an extremely common problem. The presence of holes near the bend axis can create a deformation that changes the shape and position of the hole. The best solution would certainly be to avoid designing bent sheet metal elements with holes too close to the bend lines. However, if you do not have this possibility, there are several strategies that can be adopted both by the technical department of the company that physically makes the piece, and by the operators. Partial drilling Mainly used in heavy metalwork fabrication, partial drilling involves not completing the entire shape of the hole. This makes it possible to preserve a surface useful to be supported by the matrix during deformation with the consequent stability of the perforated shape. The hole will be completed by further processing, such as with a hand plasma. As you can imagine, this technique is best used in the presence of high thicknesses and small quantities of pieces. Pre-drilling with smaller diameter All in all, similar to partial drilling, pre-drilling with a smaller diameter involves a non-complete drilling of the template to be removed during cutting. In this case, a small hole is drilled and sufficient to avoid any deformation during bending. Unlike the partial drilling technique, pre-drilling with a smaller diameter is faster and suitable for even medium-thin thicknesses and medium-large batches. In the next article, we'll continue to dive deeper into the approaches you can use to handle holes near bend lines. If you haven't already done so, we recommend subscribing to the VICLA newsletter!
Two weeks ago we discussed how important it is to know the recurring problems of sheet metal bending and we saw what the first two cases are, i.e. partial drilling and pre-drilling with a smaller diameter. Today we are going to delve a little deeper into the theme of drilling, introducing vent cuts and we will end by talking about the use of tangential bend dies. Are you ready? Tagli di sfogo It consists of providing a cut at the bend line that allows the flap to be bent up to the apex of the notch. The cut can then be restored by welding or left open depending on the end use of the piece. This method, where permitted, also guarantees absolutely outstanding results. It consists of making cut strokes or real windows that interrupt the bend line at the holes. In the presence of a high thickness, simple cuts cause tears on the ends of the bend line break. This phenomenon may not be a problem, even more so if the external radius is restored through welding and grinding. However, in the presence of elements subject to fatigue and high loads, it is advisable to operate in a different way, for example as in this image, where, thanks to an H-shaped cut, tears and potential crack triggers are completely avoided. Die width reduction The reduction of the width of the matrix is a technique that finds its best application when it is already provided for in the technical office. At the drawing or planning stage, if there is the appropriate knowledge, it is already possible to understand whether the deformation of the holes can be avoided with this system and whether the workshop has the right tooling for the purpose. If so, the technical department will necessarily have to generate a development suitable for the new condition. This also means that it is a good rule of thumb to state on the drawing which is the die to be used in production to obtain the correct part. Reducing the width of a die, as already described, causes a smaller bending radius in the sheet metal with the consequence of obtaining a part with a smaller finished size than desired. Changing the bending mode As already discussed in this volume, there are three folding methods, each with its own peculiarities: air folding, matrix bottom and coining. Depending on which mode it is adopted, there is a different constancy in the shape of the holes during bending. Working in air, in fact, the sheet metal is totally free and suspended on the die and this approach is the least favorable condition to preserve the holes from deformation. For this reason, it is more suitable to use an 88° homologated matrix for hollow bottom mode. In this case, the internal faces of the die, coming into contact with the sheet metal, reaffirm the deformations bringing the holes back to their initial shape. If high precision is required, it is advisable to consider the use of this technique already when determining the development of a part. Using tangential bend dies For several years now, special dies have been offered on the market equipped with milled semi-rollers and housed on special seats. The position of these rollers is maintained by springs that allow them to move and return to their initial horizontal position. Tangential or oscillating bend dies have many advantages in the face of a rather high purchase cost and a wider width than traditional dies that makes it more complex to make closely spaced Z folds. In the next article we will complete the topic of the most common problems by talking about venting curls. If you haven't already done so, we recommend subscribing to the VICLA newsletter! Is this your first time reading this blog? Download our press bending manual and subscribe to the newsletter!