EN
Press brake tonnage refers to the maximum bending force or bending capacity required to bend sheet metal using a press brake machine. Simply put, it represents the upper limit of force that a press brake machine can exert on a sheet of metal, and this value determines the size and difficulty of the sheet of metal that the press brake machine can handle.
Press brake tonnage plays a crucial role in the bending process. It directly determines the maximum force that the bending machine can exert on the sheet metal, and only enough force can make the sheet metal bend precisely at a predetermined angle. For example, in the manufacture of high-precision aerospace components, the bending angle of the high precision requirements, the appropriate tonnage is to ensure that the components to meet the design requirements of the key factors.
Special attention should be paid to the fact that the actual working tonnage should never exceed the working capacity of the press brake and the maximum load capacity of the tooling. Once this limit is exceeded, it will not only lead to a serious decline in bending accuracy, but also may cause a series of serious problems, such as mold damage, machine failure, and even pose a threat to the safety of the operator.
The positive effect of the correct tonnage on press brake bending
The use of the right tonnage can ensure that the press brake bending angle is accurate, so as to produce consistent size and high precision parts. Taking automobile manufacturing as an example, in the production of door panels, the precise bending angle can ensure that the door fits perfectly with the body, improving the sealing and appearance quality of the whole vehicle. Accurate tonnage control makes each door panel bending angle error is very small, greatly improving product consistency and quality stability.
Consequences of wrong tonnage
Incorrect press brake tonnage can lead to serious deviations in bending, over-bending or under-bending. In the furniture manufacturing industry, if the wrong tonnage is used in bending the metal table legs, it may lead to the bending angle of the table legs does not meet the design requirements, so that the table can not be placed smoothly, which seriously affects the quality of the product, increases the cost of reworking, and may even lead to product scrap.
Improve efficiency with proper tonnage
Optimizing press brake tonnage can significantly increase production speed and give full play to the capacity of the bending machine. In large-scale metalworking plants, the right tonnage setting can reduce unnecessary repetitive bending operations and adjustment time. For example, each press bender bending can achieve the desired result in one go, without the need for repeated reworking, which greatly reduces the processing time of each work piece, increases the output per unit of time, and improves the overall production efficiency.
The wrong tonnage leads to low efficiency
If the wrong tonnage is used, there will be frequent cases of unqualified bending, requiring constant adjustment and re-bending. This not only wastes a lot of time, but also leads to an increase in equipment downtime, reducing the utilization rate of the equipment, which in turn affects the smooth flow of the entire production process, reducing production efficiency.
Appropriate sheet metal bender tonnage to extend the life of the mold
The use of appropriate sheet metal bender tonnage can effectively reduce the pressure and wear on die components (such as punches and dies). In a metal stamping plant, the proper tonnage makes the force on the die uniform during the working process, reducing the wear and deformation caused by excessive force. In this way, the service life of the die can be extended, reducing the frequency of die replacement and lowering production costs.
Too large sheet metal bender tonnage leads to premature damage to the mold
Excessive tonnage will bring great pressure to the mold, resulting in premature wear and even damage to the mold. For example, when the tonnage exceeds the tolerance limit of the die, the punch may break and the die may deform or crack. This not only requires immediate replacement of the mold, which increases production costs, but also leads to production interruptions that affect the production schedule.
Proper sheet metal bender tonnage selection of tonnage ensures safety
Choosing the right sheet metal bending machine tonnage is critical to operator safety. In a production plant, the right tonnage enables the bending process to proceed smoothly, reducing the risk of accidents caused by improper operation or equipment failure. For example, to avoid the sudden ejection of sheet metal due to excessive force injuries, or due to equipment overload caused by mechanical failure on the operator, creating a safe working environment for the operator.
Excessive tonnage will bring many safety risks. Excessive force may lead to sudden breakage or ejection of sheet metal in the bending process, causing serious injury to the operator. At the same time, overloading the equipment may also trigger machine failures, such as leakage of the hydraulic system and damage to mechanical parts, all of which may pose a threat to the life and safety of the operator.
Thickness: There is a direct correlation between material thickness and required tonnage. In general, the thicker the material, the more force is required to bend it. For example, the tonnage required to bend a 1 mm thick aluminum plate to a specific shape is much lower than the tonnage required to bend a 5 mm thick plate to the same shape. This is because the thicker material is more resistant to deformation and requires more force to bend it.
Type: Different types of materials have different tensile and yield strengths, which also directly affects the press brake tonnage required for bending. To common materials, for example, stainless steel due to its high tensile strength, compared to mild steel in the bending of the need for greater press brake tonnage. The tensile strength of aluminum alloy is relatively low, so the CNC press brake tonnage required in bending is also smaller. In actual production, the tonnage required must be accurately calculated according to the type of material to ensure smooth bending.
Texture direction: The grain direction of the material has a significant impact on the sheet metal machine tonnage required for bending and the risk of cracking. When bending a material in the direction of the grain, the sheet metal mahcine tonnage required is usually smaller, but in materials with high tensile strength (such as stainless steel), this type of bending may increase the risk of cracking. Conversely, when bending a material perpendicular to the grain direction, the tonnage required increases due to the material’s increased ability to resist deformation, but can reduce the likelihood of cracking at the bend. For example, when machining mild steel, bending perpendicular to the grain direction results in better structural integrity, although more force is required.
Length：Metal sheet bending length has a significant impact on the tonnage requirements of a press brake machine. A longer sheet metal bend distributes the required force over a larger area, thus increasing the total tonnage requirement. For example, the tonnage required to bend a 1 meter long mild steel bar is much less than the tonnage required to bend a 3 meter long mild steel bar of the same specification. In addition, table length and die opening width also have an impact on bending. A longer table can accommodate larger sizes of material, but if the tonnage limit is exceeded, the table may be distorted. The V-opening of the mold must match the length of the bend to ensure even pressure distribution. If the die opening width is too narrow for the material thickness, the required tonnage will increase, which may cause damage to the machine and the die.
Angle: The brake bender bending angle is another key factor in determining the tonnage required. The sharper the press brake bending angle, the more the material needs to be deformed and therefore the more force is required. For example, the tonnage required to bend mild steel to a 90-degree angle is much greater than the press brake tonnage required to bend it to a 45-degree angle.
In addition, the method of bending affects this relationship. Air bending usually requires less tonnage than bottom bending or impression bending because in air bending, the material is not fully pressed into the die. However, in air bending, sharp angles may result in greater rebound, which requires tonnage to be adjusted for material properties such as tensile and yield strength.
Die Width: The width of the die opening has a significant effect on the press brake tonnage required to bend a particular material and angle. A wider die opening spreads the force over a larger surface, thus reducing the tonnage required, while a narrower die opening concentrates the force and increases the tonnage required. For example, the tonnage required to bend a 4 mm thick mild steel plate using a die with a 12 mm wide opening is less than using a die with a 6 mm wide opening. The correct match between material thickness and die opening is critical to maintaining accuracy and preventing damage to the bending machine or die.
The recommended die opening sizes for material thickness are as follows: 1 mm thick material corresponds to a 6 mm die opening width; 2 mm thick material corresponds to 12 mm; 4 mm thick material corresponds to 24 mm; 6 mm thick material corresponds to 36 mm; and 8 mm thick material corresponds to 48 mm. Using the correct mold width will ensure consistent results and extend the life of the mold. When making press brake tonnage calculations, always take into account the V-shaped opening of the die to avoid exceeding the capacity of the machine or the tonnage limitations of the bending machine.
Punch Radius: Punch radius is another key factor in press brake tonnage. A smaller punch radius concentrates the bending force in a smaller area, thus increasing the tonnage required. A larger punch radius, on the other hand, will distribute the force more evenly and reduce the pressure, but may affect the bending radius and angle. The die should be selected to match the type and thickness of the material. For example, punches for stainless steel must be able to withstand higher tensile strengths than mild steel.
Incorrect brake bender die selection may result in material distortion, uneven bending, or premature die wear. The formula for estimating the load limit of a punch is: load limit = tensile strength × material thickness × bending length ÷ safety factor. For example, when bending stainless steel with a thickness of 4 mm and a length of 1 meter (tensile strength of 84,000 PSI), it is important to make sure that the punch and die can withstand the calculated loads without exceeding their design specifications.
Upper Die Width: The width of the upper die is a key factor in calculating the tonnage of a press brake. A narrower upper die will concentrate the force in a smaller area, increasing the tonnage required. A wider upper die will distribute the force more evenly, reducing the overall load, but may affect the accuracy of bending at smaller angles or radii. The different types of upper dies and their applications are listed below:
Air Bending: Air bending is a widely used bending method with a tonnage factor of 1.0+. During air bending, the material does not come into full contact with the die, but rather the punch presses the metal partially into the V-opening of the die, with the remainder of the bending being done by the rebound of the material to create the final bending angle.
This type of bending has a number of advantages. First, it requires minimal tonnage loading, which greatly reduces wear and tear on the bending machine; second, it is suitable for a wide range of materials, such as mild steel, aluminum, and stainless steel; in addition, the bending angle can be adjusted by varying the depth of the punch, which provides a high degree of flexibility.
Bottom Bending: The press brake tonnage factor for bottom bending is 5.0+. In this type of bending, the material is pressed into the mold until it comes into full contact with the walls of the mold opening. Bottom bending produces a more consistent bending angle than air bending and is effective in minimizing material springback. Therefore, it is widely used in the production of high precision requirements, to meet the needs of some of the extremely stringent requirements for dimensional accuracy of parts manufacturing.
Embossing Bending: The tonnage factor of imprint bending is 10.0+. This type of bending achieves the most accurate bending by pressing the punch completely into the mold, causing permanent deformation of the material. Imprint bending completely eliminates springback and produces highly accurate bends. It is ideally suited for applications that demand the highest level of precision and durability, as well as for the manufacture of parts that require smaller bending radii or complex shapes.
Over-tonnage operation is absolutely to be avoided in the use of press brake machines. Once the maximum tonnage of the press brake machine is exceeded, it will bring extremely serious consequences. Critical parts of the machine, such as slider and table, may undergo serious deformation, which is often irreversible, resulting in the machine can not be repaired and scrapped. At the same time, over-tonnage can also put tremendous pressure on the molds, causing them to break or be damaged. More seriously, this will pose a great threat to the operator’s life and safety, which may lead to such dangerous situations as metal splash, machine parts falling off. Therefore, before operating the bending machine, you must fully understand the tonnage limits of the machine and mold, and prohibit over-tonnage operation.
Regular inspection and maintenance of the press brake bending machine and tonnage-related components is an important measure to ensure the normal operation of the equipment. The pressure system of the press brake needs to be checked regularly to ensure accurate pressure indication and stable pressure output. At the same time, the mold should be checked to see if there is wear, deformation or cracks. Timely replacement of molds with severe wear and tear to avoid inaccurate tonnage control caused by mold problems.
In addition, the mechanical transmission parts of the machine and the electrical control system should be comprehensively inspected and maintained to ensure that the overall performance of the equipment is good. Regular maintenance not only ensures the normal operation of the bending machine, extends the service life of the equipment, but also ensures the accurate control of the tonnage in the operation process, improves production efficiency and product quality.
In summary, the tonnage in the press brake bending process plays a pivotal role. It is directly related to the bending accuracy, operational efficiency, mold life and workplace safety. The right choice of tonnage can ensure the production of high-quality products, improve production efficiency, reduce production costs, while protecting the safety of operators. On the contrary, wrong tonnage selection may lead to a series of serious problems and bring great losses to the enterprise.
As technology continues to progress, press brake tonnage-related technology is also evolving. In the future, we are expected to see a more intelligent tonnage control system, which, through sensors and automation technology, is able to adjust the tonnage in real time according to the characteristics of the material, bending requirements, etc., to achieve more accurate and efficient bending operations.
At the same time, the development and application of new materials may also change the tonnage requirements of the bending machine and bending process. For example, high-strength, lightweight materials may require different bending force and process parameters. Therefore, companies and operators need to pay close attention to the development of the industry, and constantly learn and master new technologies and knowledge to adapt to the future development and changes in bending machine technology.
