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Introduction

A press brake is a machine tool for metal forming, which can bend and shape metal sheets.

press brakes are commonly used in sheet metal processing and manufacturing industries, such as construction, automobile, aerospace, and other industries.

Generally speaking, the workpieces manufactured by the press brake have different shapes, which can be simple or complex parts.

The press brake is equipped with different pressure systems, including mechanical, hydraulic, electric, and pneumatic pressure systems.

The power device applies pressure to the ram, drives the upper die to move downward, and presses the metal plate into the lower die.

In this way, a bending is completed. After repeated and accurate bending, the required workpiece is finally finished.

The die of the press brake is divided into the upper die(punch) and the lower die.

The upper die and lower die of different shapes act on the plate together to form workpieces of different shapes.

Overview of Press Brake Tools and Accessories

Different Types of Press Brake Tools and Their Functions

The tools of the press brake include conventional die assembly, upper die (punch), and V-shaped die.

It is necessary to select different press brake dies according to different metal sheets.

For example, for metal plates with high tensile strength, the hardness of the die should also match the plate.

Otherwise, it will cause damage to the die or inaccurate bending of the workpiece.

The conventional tooling group includes an upper die and a lower die, and the two matching dies to bend the metal sheet together.

The punch is generally made of materials with high hardness, which can effectively extrude or cut the plates.

The lower die also needs the same hard material, as the punch will press the plate into the lower die.

The upper die (punch) of the press brake has some special shapes.

These punches with special shapes and angles can process workpieces with specific shapes.

These punches include standard punch, gooseneck punch, sash punch, arrow punch, acute punch,etc.

The materials used for press brake dies are generally hardened steel, such as chromium-molybdenum steel.

The use of materials with higher hardness can prevent punch cracking caused by excessive pressure and plate hardness.

The lower die of the press brake can also be divided into the V-shape die, U-shape die, single die, and double die.

The material of V-shape and U-shape dies is the same as that of the punch, and they are durable materials with high hardness.

The opening size of the V-shape die will affect the selection of the bending radius of the workpiece and the selection of the bending method.

The groove of the lower die is matched with the upper die so that the sheet can be fixed and form the final shape of the workpiece.

These punches and dies are the main tools for the press brake.

The press brake also has some other very important auxiliary tools, including the back gauge, clamping tool, support rack, etc.

The other parts of the press brake are combined to ensure the accuracy of the bending position, angle and speed.

In this way, the accuracy and quality of the workpiece can be improved.

Using High-Quality Press Brakes Tools and Accessories

The importance of using high-quality press brake punches and dies and accessories is self-evident.

Precise press brake dies and other accessories can improve the accuracy of parts.

The material of the punch and die should be hard enough to prevent it from being worn and broken.

High-quality tooling materials can also extend the service life of the tooling and keep the mold from deformation.

Good tooling quality can ensure the quality of the workpiece bending, thereby reducing the error of the parts.

It can improve the production efficiency of the press brake and reduce production costs.

The dies with high matching degrees and quality are very efficient in sheet bending.

Advanced and high-quality accessories can improve the bending speed, accuracy, and final product quality.

For example, the accurate positioning of the backgauge and each axis can improve the accuracy of the flange length and size of the workpiece.

High-quality hydraulic devices can provide stable stroke and avoid bending angles caused by inconsistent speed.

High-quality toolings and accessories can ensure the bending quality of the press brake and prolong the service life of the machine.

Thus, the product quality is guaranteed, the production efficiency is improved, and the production cost is reduced.

Common Press Brake Tools and Accessories

Press Brake Dies and Punches

The die of the press brake is divided into the upper die and lower die, which jointly bend the sheet.

The upper die can be divided into right angle, acute angle, obtuse angle, gooseneck die, standard die, etc.

The lower die includes the V-shaped die, U-shaped die, single groove and double groove die.

The upper die, driven by the ram, presses the metal sheet into the lower die and bends it into a certain shape.

The material of the die is usually steel with high hardness, so as to prevent the die from breaking.

Angle Gauges and Protractors for Measuring Bend Angles

When bending, the tools used to measure the bending angle of the metal plate are called angle gauge and protractor.

Press brake punches and dies bend metal sheets into different shapes and angles.

In order to ensure the accuracy of bending angle, angle gauge and protractor can be used.

Use the angle gauge and protractor to correct the bending angle and ensure that the bending angle and size are correct.

There are many types of angle gauges and protractors, which are generally supported by steel materials.

Press Brake Tools Lubrication

The use of lubricants can prevent wear caused by long-term use of the press brake die and parts.

Lubricants for the press brake include cutting oil, grease and wax.

The use of lubricants can improve the bending efficiency and service life of the press brake.

Safety Protection Dvices

The press brake needs to be equipped with safety and protective devices to protect the operator from injury during bending.

Safety protection devices include protective fences, gloves and other personal protective equipment.

There are also some special protective devices installed on the operating parts of the press brake.

The brake caliper of the press brake will be equipped with a guard plate, which is a thermal braking part, and the operator will be injured if contacted.

Conclusion

This blog introduces the common press brake tools and the importance of using high-quality tools.

Tools of the press brake include press brake punches and dies, backgauge, protractor, hydraulic device, protective device, etc.

High quality press brake tools are the indispensable part of a high quality press brake.

In the long run, the production cost can be effectively reduced by choosing the press brake with high quality and moderate price.

The press brake produced by ADH has the characteristics of high quality, high performance and high cost performance.

If you need to know more about ADH press brake, you can contact our product experts.

FAQs

How Do You Set up A Press Brake Tool?

Before installing the press brake toolings, it is necessary to carefully review the drawings.

Understand the characteristics and thickness of bending materials, flange size, tolerance, bending angle, radius and other parameters.

Next, determine the bending method, air bending, bottom bending or coining.

Then calculate the tonnage required for bending. Different bending methods require different bending forces.

Determine the number of punches and dies to be installed, and then install and align the upper and lower dies.

Slide the punch into the fixture and hold it in place.

Then install the bottom die, do not install it too tightly, and keep it loose.

Lower the punch, slide the punch into the bottom die, and ensure that the upper and lower dies are aligned and close.

Finally, tighten the fastening screws and clamps of the upper and lower dies.

Overview of Shearing Machine

A sheet metal shearing machine is a machine specially used for shearing metal plates in the sheet metal industry.

It is usually composed of blades, pulleys, baffles, electric control systems and other components, which can cut metal sheets into various shapes and sizes.

The die of the plate shearer has many shapes, including the straight blade, the round blade, etc.

Plate shearing machines are usually used to manufacture automobiles, aerospace, machinery manufacturing, household appliances, and other products, as well as in the construction industry.

The performance of the plate shearing machine depends on the shearing capacity, accuracy, speed, reliability, etc.

What Are the Types of Shearing Machines?

Depending on the drive mode, common types of shearing machines mainly include manual sheet metal shearing machines, mechanical shearing machines, hydraulic shearing machines, and pneumatic shearing machines.

Manual plate shears refer to the equipment that can realize the up and down movement of the blade through manual operation to complete the cutting of plates.

The manual plate shears are easy to operate and suitable for cutting small plates, but their cutting accuracy is low and can not meet the needs of large plates.

The mechanical shearing machine is driven by a power device composed of a motor, a flywheel, a worm shaft, and a clutch.

Mechanical shearing machine has fast cutting speeds and more strokes per minute than the hydraulic shearing machine.

The flywheel of the mechanical shearing machine can store energy, so a motor with less horsepower can be used.

According to the operation mode, the mechanical shearing machine can be divided into the up-moving type and the down-moving type.

The power source of the hydraulic shearing machine is the hydraulic cylinder and motor.

The motor drives the hydraulic cylinder to send hydraulic oil pressure to the piston. The piston movement provides power to the piston of the upper blade.

The hydraulic shearing machine has a longer stroke and different load capacities. The materials cut with a hydraulic shearing machine are smooth with few traces.

Hydraulic shearing machines are characterized by large shearing force, stable action, and good controllability.

The hydraulic shearing machine can be divided into the swing beam shearing machine and the guillotine shearing machine.

The swing beam shearing machine realizes shearing movement by swinging the tool rest, which has the advantages of high speed, high shearing accuracy, and high efficiency.

The guillotine shearing machine can be either hydraulically driven or mechanically driven.

Its main components include a working table, upper and lower blades, the hydraulic piston, the clamping tool, and the blank holder.

The guillotine shearing machine can cut plates of different thicknesses and lengths.

The movable blade of the guillotine shearing machine can be straight or inclined to reduce the force required for cutting.

The guillotine shearing machine has fast cutting speed, large cutting thickness, and length, and is suitable for mass production.

However, the cut edges are rough and not very beautiful.

The pneumatic shearing machine refers to the equipment that can realize the up and down movement of the blade through the pneumatic system to complete the cutting of plates.

The pneumatic plate shearing machine can adjust the movement of the blade through air pressure and has high shearing speed and accuracy.

The pneumatic shearing machine is usually used for cutting special plates, such as plates with high hardness and strength.

As the pneumatic shearing machine has high cutting speed and accuracy, they are suitable for high-speed and high-precision cutting.

The shearing machine has different ways of shearing plates, which can be divided into the linear shearing machine and the circular shearing machine.

The linear shearing machine is driven by hydraulic devices and can cut metal plates that are thicker.

The circular plate shearing machine is driven by a motor and is able to cut round metal plates.

Each type of shearing machine has its own advantages and is suitable for different cutting.

Users can select the type of shearing machine suitable for themselves according to their needs and the characteristics of the materials.

For example, if users need to cut small plates, the manual shearing machine may be a good choice.

If the user needs to cut large plates, the guillotine shearing machine or pneumatic shearing machine may be a better choice.

What Are the Main Components of the Shearing Machine?

The main components of the shearing machine include the working table, upper and lower shearing blades, clamping tools, baffles, and electric elements.

The blade is the main working part of the shearing machine, usually made of high-strength steel, with good hardness and wear resistance.

The blade can be moved up and down to cut the sheet. The clamp is used to fix the metal sheet to be cut, so as to cut more accurately.

The baffle is a safety protection part of the plate shearing machine.

It is usually made of high-strength metal materials, which can prevent the plate from being impacted by external forces.

The baffle is usually installed near the blade edge of the shearing machine, which can effectively protect the safety of workers.

The electric elements are the control part of the shearing machine, which is usually composed of a circuit board, a motor, and a controller.

The electric elements can monitor and control the running state of the shear to ensure the safe operation of the shearing machine.

What Is the Working Principle of the Shearing Machine?

The working principle of the shearing machine is to cut the sheet metal into the required size and shape by moving the blade up and down.

First, it is necessary to place the plate on the blade of the shearing machine to make the plate contact with the blade.

Through the control of the electric elements, start the motor of the shearing machine to make the blade move up and down.

The blade shears the sheet through the driving system.

During the whole working process, the protection device will play the role of safety protection to prevent the plate from being impacted by external forces.

The shearing machine will also adjust the speed of the blade according to the type and size of the materials to achieve accurate shearing of the plate.

Features of the Shearing Machine

The shearing machine shears the metal plates to the required size through the moving blade up and down, with very high accuracy.

The shearing machine can control the movement speed of the blade through the electric elements to achieve accurate shearing.

The shearing machine can cut a wide range of materials, including stainless steel plates, aluminum plates, copper plates, and other different types of plates.

The shearing machine is easy to operate and safe. Now the operation of CNC shearing machine only needs to master the basic operation methods.

The safety protection parts of the shearing machine can effectively prevent the plates from being impacted by external forces and protect the safety of workers.

What Is the Shearing Machine Mainly Used for?

The shearing machine can achieve high-precision and high-speed cutting of plates, providing effective support for industrial production.

Shearing machines are widely used in machinery manufacturing, aerospace, automobile manufacturing and other industries.

In the aerospace industry, the shearing machine can be used to cut high-strength steel plates to make aircraft parts.

The shearing machine can be used to cut steel plates and aluminum plates to manufacture parts such as automobile bodies and doors.

The shearing machine can also be used in household appliances, electronic products, building decoration, and other fields.

For example, in the household appliance industry, the shearing machine can be used to cut stainless steel plates to make products such as refrigerators and airconditioners.

In the electronics industry, the shearing machine can be used to cut aluminum plates to make products such as computer shells and mobile phone shells.

What Are the Blade Materials of Shearing Machine?

The blade of the shearing machine is mainly made of high-speed steel, carbon steel and other materials.

High-speed steel is a kind of commonly used blade material with high wear resistance and rigidity.

High-speed steel has high stiffness, which can effectively improve the cutting efficiency of the shearing machine.

High-speed steel blades can effectively improve the shearing accuracy of the shearing machine after fine processing.

Carbon steel is a common blade material with low cost and high toughness.

The carbon steel blade has high toughness, which can effectively resist the vibration and deformation of the blade during shearing.

After fine heat treatment, the carbon steel blade can effectively improve the shearing accuracy of the shearing machine.

In general, the blade materials of the shearing machine include high-speed steel, hard alloy, and carbon steel and so on.

The selection of blade materials depends on the working conditions and budget of the shearing machine.

Future Development Trends of the Shearing Machine

The future development trend of the shearing machine may be affected by many factors, including economic development, market demand, technological progress.

The shearing machine may become more advanced and have more intelligent functions with the development of intelligent technology.

Such as automatic adjustment of blade position, automatic identification of plate type and thickness, etc.

The shearing machine may become more efficient, and more efficient production management and quality control can be achieved through digital technology.

The shearing machine may become more integrated to achieve seamless connection with other equipment and improve production efficiency and quality.

The shearing machine will decrease the impact on the environment by reducing energy consumption and emissions of pollutants.

Conclusion

This article introduces the main types, main components, working principles, characteristics, applications, blade materials, etc. of shearing machines.

Plate shearing machines are widely used in the manufacturing industry and are very edible machinery and equipment.

To purchase a suitable shearing machine, you need to know the function, price, warranty, etc. of the shearing machine in detail.

ADH is a sheet metal processing machine manufacturer with 20 years of experience.

The quality and performance of the press brake, plate shearing machine, laser cutting machine, and other machines are guaranteed.

FAQs

What Are the Famous Manufacturers of the Shearing Machine?

Plate shearing machine is an important manufacturing equipment, which is produced and sold by many manufacturers.

There are many famous shearing machine manufacturers, such as Adira, Amada, JMT USA, Cincinnati, Baykal, LVD, Safan Darley, and ADH.

These manufacturers have produced high-quality and high-performance shearing machines, which are widely welcomed by customers.

Price of the Shearing Machine

The price of the shearing machine is affected by many factors, including manufacturer,quality, function, and performance.

In addition, market demand and share will also affect the price of the shearing machine.

In order to obtain more detailed information, it is recommended that you contact the manufacturer for consultation.

What Are CNC Press Brake and NC Press Brake?

NC press brake or CNC press brake is a kind of press brake that uses a CNC system to control the bending operation process.

With the CNC system, the operator can program various bending parameters of the workpiece through the controller.

Repeated bending can be performed after the controller sets all parameters.

This undifferentiated repeated bending process can ensure the bending speed and accuracy.

The most apparent difference between the CNC press brake and the NC press brake is that the controller is more advanced.

The controller of the CNC press brake can carry out complex programming, which makes the operation more accurate and the degree of automation higher.

The CNC press brake is more suitable for complex workpieces and mass production.

Advantages and Disadvantages of NC press brake

The NC press brake controls the up-and-down movement of the punch through the NC system to bend the metal sheet.

NC press brake has many advantages over manual press brake.

For example, the consistency of bending speed and accuracy is improved, and the dependence on skilled operators is reduced.

Compared with the manual press brake, NC press brake greatly improves the speed and accuracy of bending.

NC press brake adopts the NC system to control the bending process, including stroke speed, bending times, etc.

In this way, repeated bending can be carried out while ensuring the consistency of speed and various parameters.

NC press brake can improve the efficiency of parts production and ensure the quality of finished products.

In addition, compared with the manual press brake, NC press brake reduces the skill requirements for operators.

The use of the manual press brake requires the operator to manually set the machine and adjust the die.

With NC press brake, most bending programs can be completed by programming the controller or setting parameters.

The operator may only need to load and unload the sheet metal.

As long as the NC system is programmed, the NC press brake can also perform automatic bending.

The machine will bend the workpiece according to the procedures and steps, which can improve production efficiency.

Compared with the manual press brake, the NC press brake has higher costs for machine purchase and personnel training.

In addition, although the NC press brake can be operated automatically, it is not as efficient as a skilled operator when dealing with emergencies or complex bending.

Advantages and Disadvantages of CNC Press Brake

CNC press brake is the full name of the computer numerical control press brake. Like the NC press brake, it is used for bending metal sheets.

However, the CNC system of CNC press brake is more intelligent than that of the NC press brake.

Compared with the NC press brake, the CNC press brake has higher bending speed, precision, and automation.

Because the controller of the CNC press brake is more advanced, it can perform more accurate bending.

After programming, accurate bending speed, angle, and the final accurate workpiece can be obtained.

The accuracy and quality of the workpiece have been greatly improved, reducing the production cost.

CNC press brakes can also produce workpieces with more complex shapes.

Because the CNC controller is more advanced, it can be programmed through complex algorithms.

In this way, the bending accuracy of the die can be controlled, which is helpful for processing workpieces with complex shapes and angles.

The degree of automation of CNC press brake is also higher than that of NC press brake.

Through programming, the CNC press brake can bend complex workpieces according to the program.

A more advanced CNC press brake is a bending center with a robotic arm.

CNC press brake is suitable for complex bending, which can improve the output and bending efficiency.

The disadvantage of CNC press brake is its high cost. Compared with NC press brakes, the purchase and training costs of CNC press brakes are high.

Because the operation of a CNC press brake is more complex, the requirements for operators are higher than that of an NC press brake.

CNC press brake is very suitable for complex workpiece bending or factories that have requirements for mass production.

Because of its high accuracy, the processed workpiece hardly needs to be reworked.

Comparison of NC Press Brake and CNC Press Brake

One of the differences between the CNC press brake and the NC press brake is the function and accuracy of the control system.

NC press brake mainly controls the bending process through the NC system.

The controller of the CNC press brake is controlled by the computer control system.

The computer control system can program complex algorithms and accurately control the dies, back gauge, and other parts.

Another difference between the CNC press brake and the NC press brake is the degree of automatic operation.

The CNC press brake has a higher level of automation. For example, the bending center is equipped with a robotic arm, so the operator only needs to feed and unload the material.

NC press brake is more popular because of its low cost and is suitable for most metal sheet bending.

Although CNC press brake is more expensive, it has a high level of automation and bending accuracy and can process large quantities of complex workpieces.

Conclusion

This blog introduces the advantages, disadvantages, and differences between CNC press brakes and NC press brake

In general, the CNC press brake is more advanced than the NC press brake, which can provide more accurate bending and higher quality products.

The NC press brake has a high cost-performance ratio and is cheaper than the CNC press brake, but it has complete functions and high bending accuracy.

If you need to purchase a CNC press brake or NC press brake, you can contact the product expert.

ADH is a professional manufacturer of sheet metal processing machines, which can provide you with cost-effective products and high-quality services.

FAQs

What Are the World's Famous Press Brake Manufacturers?

The global market demand for sheet metal processing is still growing, so the press brake market is also growing.

There are many press brake manufacturers, how to choose the right press brake brand?

At present, the world-famous press brake manufacturers include Amada, Trumpf, Accurpress, Bystronic, Durma, Salvagnini, LVD, Prima, etc.

Famous brands have brand guarantee, so the quality and after-sales service are guaranteed.

But the price is relatively expensive. You can choose a relatively unknown but cost-effective press brake brand according to your own needs.

What Is A Hydraulic Press Brake?

Hydraulic press brake is a kind of press brake, which uses hydraulic device as power device.

The main components of hydraulic press brake include hydraulic device, ram, punch and die, controller, etc.

The hydraulic press brake has two hydraulic cylinders, which are driven by the motor to generate driving force.

Hydraulic press brake has the advantages of high speed, small resistance, high bearing capacity and large pressure.

Hydraulic press brake has different types of motors and tonnage, and can handle materials with different characteristics.

In the 3D design of parts, the design dimension of parts needs a total amount and range that can be changed.

The designers of parts need to consider the range of product dimension changes when designing.

If the dimension variation range of the part is not appropriate, such as if the sheet metal tolerance is too small.

Then, a more precise parts manufacturing process will be required to ensure the precision of the workpiece.

Only a few manufacturers have such technology, and the production cost will greatly increase.

If the tolerance range is too large, the quality of parts cannot be guaranteed.

Therefore, a reasonable tolerance is to calculate the appropriate variation range of the part size.

What Is Sheet Metal Tolerance?

Sheet metal tolerance is a range that allows the design dimensions of parts to change.

The tolerance range is the upper and lower limit of the variable workpiece design size.

The tolerance zone of sheet metal tolerance refers to an area limited by upper and lower deviations.

Loose tolerances have a wider tolerance zone, while strict tolerances have upper and lower limits of a smaller range.

A strict tolerance range also means that the dimensions of the workpiece are more precise.

Why Do We Need Sheet Metal Tolerance?

During workpiece processing, slight differences in metal plates will lead to differences in final products.

The thickness, purity, texture, age, and processing method of materials will affect the quality of sheet metal processing.

Allowing a certain tolerance range can make the workpiece fit better.

It can also reduce the production cost, provided that it is controlled within a reasonable range.

Because too precise size requires more professional technology and equipment, it usually takes longer to complete.

Therefore, in part design, the use of reasonable tolerances has an important impact on the size of parts.

Relative Definitions of Tolerances

There are many forms of tolerance in sheet metal processing. Tolerance can be used for the length, width, and thickness of parts.

Tolerances can be set for wall thickness, bends, curls, countersinks, hems, holes, slots, notches, tabs, etc.

The parts not only have dimensional tolerance but also have differences between the actual form or mutual position of the points, lines, and surfaces constituting the parts and the form and mutual position of the ideal geometry.

This difference in form is called form tolerance, and the difference in mutual position is called position tolerance, which is collectively called tolerance of form and position.

Dimension tolerance: referred to as tolerance for short, it refers to the absolute value of the difference between the maximum limit dimension and the minimum limit dimension.

Or the difference between the upper deviation and the lower deviation. It is the allowable variation of size.

Position tolerance: refers to the total variation allowed by the position of the associated actual feature to the datum.

The positional tolerance is an error that limits the geometric relationship between the measured feature and the datum feature.

According to their different geometric relations, position tolerance can be divided into orientation tolerance, positioning tolerance and runout tolerance.

Tolerance grades: refers to the grades that determine the accuracy of dimensions.

The international standard is divided into 18 grades.

The larger the allowable variation range (tolerance value) of size, the smaller the processing difficulty.

IT01 to IT4 - for the production of gauges, plug gauges and measuring instruments.

IT5 to IT7 - for fits in precision engineering applications, IT8 to IT11 - for general machining.

IT12 to IT14 – for sheet metal processing or stamping, IT15 to IT16 – for casting, general cutting, etc.

IT17 to IT18 – for tolerance of plastic molding dimension, general outline dimension of surgical instruments, cold working, and welding dimension.

Tolerance symbol: the dimension tolerance is an absolute value without a sign.

Limit deviation=limit dimension - basic dimension, upper deviation=maximum limit dimension - basic dimension, lower deviation=minimum limit dimension - basic dimension.

When the basic dimensions are the same, the smaller the dimensional tolerance, the higher the dimensional accuracy.

The dimension tolerance is equal to the difference between the maximum limit dimension and the minimum limit dimension or equal to the difference between the upper deviation and the lower deviation.

How to Determine Sheet Metal Tolerances?

Part tolerance refers to the dimensions without tolerance indications in the design and manufacture of parts.

It also refers to those dimensions that are not included in the dimension chain and have no direct impact on the fit properties.

From the definition of tolerance, part tolerance has an important influence on the dimensional fit of parts in mechanical design.

If the part tolerance cannot be selected properly, the part design dimension chain will be incomplete.

In the process of tolerance marking, some parts with lower accuracy requirements can use general tolerances.

If the requirements for precision are high, the tolerance shall be specified in detail in the mechanical design.

Ensure that the part tolerance can meet the actual needs.

The function of a part determines the size, shape, location, and other requirements of its corresponding elements.

The selection of tolerance grade should ensure the design and quality requirements of parts.

The processing cost, product performance, function, service life, and fuel consumption should also be considered.

Forming or bending+/- 0.508 mm (0.020")
Bend to hole or feature+/-0.254 mm (0.010")
Diameters with inserts+/-0.0762 mm (0.003")
Angularity+/- 1°
Holes+/-0.127 mm (0.005")
Edge to edge±0.127 mm (0.005")
Edge to hole±0.127 mm (0.005")
Hole to hole±0.127 mm (0.005")
Hole to hardware±0.254 mm (0.010")
Edge to hardware±0.254 mm (0.010")
Hardware to hardware±0.381 mm (0.015")
Bend to hole±0.381 mm (0.015")
Bend to hardware±0.381 mm (0.015")
Bend to edge±0.254 mm (0.010")
Bend to bend±0.381 mm (0.015")
TOLERANCE GUIDELINES

How to Do Tolerance Analysis?

The methods of tolerance analysis are mainly one-dimensional and three-dimensional.

The one-dimensional method does not need to buy software, so the cost is low, while the three-dimensional method costs more.

There are also two different methods for one-dimensional tolerance analysis, one is the worst case and the other is the root mean square method (RSS).

The second method belongs to the category of statistical methods, while the limit method is relatively simple.

Upper dimension limit USL: 10.2+10.2+10.2+10.2+10.2=51

Lower dimension limit: 9.8+9.8+9.8+9.8+9.8=49, so the fluctuation range of dimension D is 49~51

The limit method is the direct accumulation of each size boundary, while the statistical method is to consider the probability of each size to calculate the probability of each size after accumulation.

If we want to use the probability method to analyze, we need to know the respective probability of each dimension.

The following is the distribution probability of dimension A. If it is a stable process, then it should be a normal distribution.

Then we need to know the overall distribution, and we need to know the two parameters of the normal distribution, the mean and the standard deviation.

The standard deviation describes the discrete state of a distribution. It is a measure of the average dispersion of a group of data.

The standard deviation is large, indicating that there is a large difference between most values and the average value.

The small standard deviation indicates that the difference between most values and the average is small.

After knowing the mean value and standard deviation, we can see the distribution of this dimension.

As shown in the figure above, the mean value is 10 and the standard deviation is 0.067.

If two dimensions are accumulated, the mean value is the same, and the standard deviation is different, then the cumulative distribution is completely different.

The results will be different if the distribution state of dimension fluctuation is different.

The original definition of tolerance is the way of limit definition, which can not describe a distribution well.

Two parameters are required to describe a distribution, mean value and standard deviation.

In order to associate with the original interval tolerance, another parameter - CPK needs to be introduced.

To simplify the description, we assume that the center does not shift, CP=CPK.

As shown in the figure below, with a tolerance range and CP, you can know the standard deviation. Add the mean value and the normal distribution can be determined.

The following table shows the sigma level corresponding to CP (CPK). CP (CPK) 2 means 6 sigmas, and CP (CPK) 1.67 means 5 sigmas.

When we know CP (CPK), we can get the sigma level, and we know the normal distribution.

Therefore, the mean value, tolerance range, and CP (CPK) should be known during tolerance analysis.

If we know the distribution of all dimensions in the dimension chain, we need to calculate the distribution of the total variation.

We need the calculation formula of RSS(Root Sum Square), that is, the square of the standard deviation of the normal distribution of the overall standard deviation is equal to the square sum of the standard deviation of each sub-distribution.

Therefore, the standard deviation of each dimension=the sigma level corresponding to the tolerance/CP, as shown in the figure below σ expresses the standard deviation.

σ²= (tolerance/process sigma) ²

Stacking different σ² is the total distribution of the overall standard deviation σ²

Finally, an excel template can be used to implement the analysis process.

Fill the relevant parameters of each dimension into the table in the template to get the stacking results of the overall standard deviation.

Conclusion

This blog introduces the basic knowledge of sheet metal tolerance and how to conduct tolerance analysis.

The design of parts is becoming more and more complex, and correspondingly, the tolerance is becoming more and more strict.

In order to achieve sheet metal tolerance in part design, manufacturers need to use precise machines for production.

ADH has 20 years of experience in sheet metal processing machine manufacturing.

Our products include press brakes, shearing machines, fiber laser cutting machines, etc.

If you need to buy a sheet metal processing machine, you can contact our product experts to get detailed information.

FAQs

What Is Sheet Metal Flatness Tolerance?

Flatness is a concept of form tolerance. The symbol of flatness is a circle (○), which is an index limiting the variation of the actual circle to the ideal circle.

It is a requirement for a circular contour of parts with cylindrical surfaces (including conical surfaces and spherical surfaces) within a normal section (a plane perpendicular to the axis).

What Is Sheet Metal Standard Tolerance?

A standard tolerance is any tolerance listed in an international standard to determine the size of the tolerance zone.

The standard tolerance is divided into tolerance grades, tolerance units and basic dimensions.

Generally speaking, standard tolerances are divided into 18 grades.

For parts with a certain size, the higher the standard tolerance level, the smaller the standard tolerance value, and the higher the accuracy of the size.

Various errors may occur when bending sheet metal with the press brake.

The causes of these errors include inaccurate bending radius, less bending force, and improper die clearance, etc.

The positioning error of the back gauge and the bending calculation error will also lead to inaccurate workpiece bending.

The bending angle of the workpiece is sometimes different from the calculated angle.

The main reason may be that the press brake is not leveled, or the crowning mechanism does not work.

Press Brake Parallelism

The ram and workbench will gradually deform in the long-term bending process.

This kind of deformation will lead to uneven force on the sheet metal, resulting in an uneven edge of the workpiece and reduced bending accuracy.

Therefore, the deformation of the ram and the workbench must be compensated by the crowning mechanism.

In this way, the force exerted by the ram on the plate is uniform, so as to ensure the bending accuracy of the workpiece.

The crowning mechanism of the press brake includes hydraulic crowning and mechanical crowning.

The electro-hydraulic press brake can be equipped with a hydraulic crowning mechanism.

The hydraulic cylinder on the beam and the auxiliary hydraulic cylinder under the workbench compensate for the ram and the workbench at the same time.

The hydraulic cylinder generates downward force, and the auxiliary hydraulic cylinder generates upward force so that the deformation of the ram and the workbench can be offset.

The whole hydraulic crowning mechanism is controlled by the numerical control system.

The compensation force can be set according to the sheet metal thickness, tensile strength, and die opening size.

Another compensation method is mechanical crowning, and the main working principle is through a triangular wedge structure.

The mechanical crowning mechanism needs to place two base plates above and below the workbench, which are composed of several wedges.

The upper and lower base plates are connected by disc springs and bolts, and the motor is used to drive the wedge to move relatively.

In this way, a curve can be formed to offset the original bulge.

Appropriate Sheet Metal Bending Method

Sheet metal bending method also affects the metal bending accuracy. There are three main bending methods.

The three methods are air bending, bottoming, and coining, which are distinguished according to the relationship between the end die position and the sheet metal thickness.

Using the air-bending method, the die and the workpiece do not need to be in full contact.

And the bending force required for air bending is relatively small.

The punch presses the sheet against the two points on the die shoulder into the U-shaped or V-shaped die.

The angle of air bending is generally determined by the shape and stroke of the punch and lower die.

The proper stroke depth can achieve more accurate bending.

The degree of springback after load release varies with the compressive strength of materials.

Different springback will lead to the change of bending angle. To modify the angle, you need to apply a certain amount of pressure to adjust it.

The bending angle error of air bending is about 0.5 degrees.

When using the bottoming method, the workpiece is placed at the opening of the punch and V-shaped die.

The opening size of the V-shaped die depends on the thickness of the sheet metal.

Generally speaking, the opening size of the V-shaped die is 6 to 10 times the thickness of the sheet metal.

The bottoming die changes according to the bending angle and material thickness.

After the load is released, the springback of the sheet is less, so the accuracy of the bottoming is higher.

When using the coining method for bending, the punch will completely press the material into the lower die.

The bending force required for coining is very large, which can make the material permanently shaped.

And the material springback after coining is very small, so the bending accuracy of this method is very high.

Sheet Metal Bending Parameters

In addition to selecting a suitable bending method, it is also necessary to calculate the bending parameters of the workpiece.

The process of metal bending makes the inner surface of the metal compressed, while the outer surface structure will be stretched.

Therefore, you need to know the tensile value of the material and calculate the minimum flange tolerance length.

These parameters include bending radius, K factor, bending deduction, bending allowance, setback, etc.

Material Properties

If the properties of the material are inconsistent, the bending angle of the workpiece will change when using air bending.

Moreover, if the plate thickness is the same and the die opening becomes narrower, the bending angle of the workpiece will change more.

Inconsistent material may still be within the thickness and strength tolerances of the mill.

Because the tensile strength of many materials is within a certain tensile strength tolerance.

In addition, pay attention to the outer surface of the sheet, for example, different natural texture directions require different bending pressures.

Generally speaking, these values are not the most accurate, so the angle and length need to be adjusted when bending.

Press Brake Balanced Operation

If it is allowed to run stably and bend the sheet more finely, then the press brake needs to be balanced.

Support the intermediate frame of the bending machine on a suitable bearing surface, clamp one end and support the other end.

During the formal operation, when the workpiece is rotating, first make the lower two supporting claws touch the supporting surface of the workpiece evenly and then lock it.

Then tighten the upper cover and adjust the position of the upper support claw until it is locked properly.

In the whole process, it must be ensured that all supporting claws of the intermediate frame of the press brake are evenly applied.

As far as possible, a layer of pure copper sheet or fine emery cloth should be placed between each supporting claw and the supporting surface of the intermediate frame.

This is to prevent the supporting claw from wearing the workpiece surface.

We can balance the press brake according to the above points to make it run smoothly.

Conclusion

This paper introduces some methods to improve the bending accuracy of the workpiece.

It includes the selection of the bending method, the leveling and compensation mechanism of the machine, etc.

It also includes the selection of bending materials and the accuracy of bending parameters.

ADH is a sheet metal processing machine manufacturer. Our press brake can provide customers with efficient and accurate bending.

ADH products have high performance, competitive price, and perfect after-sales service.

If you need to know about our press brake, you can browse our product page or contact our product experts.

FAQs

What Are the Possible Problems with Sheet Metal Bending?

The accuracy of metal forming can only be ensured by the correct positioning of the workpiece, matching die, reasonable die clearance, bending radius, etc.

If the parameter calculation error is too large, the die clearance is not appropriate, or the workpiece positioning is not accurate, the workpiece quality will be poor.

Various problems may occur to the workpiece, such as cracks at the bending, uneven edges of the bending workpiece, wrong bending size, convex surface of the workpiece, etc.

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