Five Attention Points When Purchase Press Brake Machine

Purchase press brake machine is a necessary investment in a sheet metal processing factory, and so it is very important for all customers know how to choose a press brake that can perfectly bend workpieces. This article introduces five attention points customers need to know before they purchase press brake machines.

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1. Workpieces:

The first important point to consider is the workpiece customers want to produce, and all customers goal is to buy a press brake that can complete the bending task with the shortest table and the smallest tonnage. To choose the perfectly matched machine model, customers should carefully consider their plate material grades, plate maximum thickness and length. If most of the work is mild steel with a thickness of 2mm and a maximum length of mm, the bending force need not be greater than 50 tons. However, if you are doing a lot of bottomed die forming, maybe a 160 ton machine should be considered.

Well, assuming the max. material thickness is 6mm, max. Length is mm, the bending force requires 200 tons, and bottomed die bending (corrected bending) requires at least 450 tons. If the majority of workpieces are mm or less, the tonnage is almost halved, greatly reducing the purchasing cost. In this case, choose the machine model based on workpiece is very important.

2. Deflection

Under the same load, the deflection of the mm press brake machine table and slider is 4 times that of the mm machine. That said, shorter press brake requires less shim adjustment to produce acceptable parts. Reduced shim adjustment in turn reduces setup time.

Material grade is also a key factor. Compared to mild steel, stainless steel typically requires around 50% more load, while most grades of soft aluminium require around 50% less. You can always get a press brake tonnage table from the press brake manufacturer that shows an estimate of the tonnage required per foot of length for different thicknesses and materials.

The old fashion hydraulic NC press brake needs customers to pay very attention to table deflection because this is the key point to affect the bending precision, but now CNC press brake machine can automatically adjust the deflection by its CNC controller.

3. Bending radius of workpieces:

When bending the workpieces, the bending radius is 0.156 times the opening distance of the die. During the bending process, the opening distance of the die should be 8 times the thickness of the metal material. For example, when forming 2mm mild steel using a 12.7mm gap, the part has a bend radius of about 1.98mm. If the bending radius is almost as small as the material thickness, a bottomed die forming is required. However, the pressure required for forming a bottomed die is about 4 times greater than that of free bending.

If the bending radius is smaller than the material thickness, a punch with a front-end fillet radius smaller than the material thickness must be used, and the imprint bending method must be resorted to. In this way, 10 times the pressure of free bending is required. For free bending, punches and dies are machined at 85° or less (smaller is better). When using this set of dies, pay attention to the gap between the punch and die at the bottom of the stroke, and the overbending enough to compensate for springback to keep the material around 90°. Generally, the springback angle produced by the free bending die on the new bending machine is ≤2°, and the bending radius is equal to 0.156 times the opening distance of the die. For bottomed die bending, the die angle is generally 86 to 90°. At the bottom end of the stroke, there should be a gap slightly larger than the material thickness between the punch and the punch. The forming angle is improved because the bottomed die bends to a higher tonnage (approximately 4 times that of a free bend), reducing the stresses that normally cause springback within the bend radius.

Imprint bending is the same as bottomed die bending, except that the front end of the punch is processed to the required bending radius, and the punch and die gap at the bottom of the stroke is smaller than the material thickness. Springback is essentially avoided by applying enough pressure (about 10 times the free bend) to force the front end of the punch into contact with the material. In order to select the lowest tonnage specification, it is best to plan for a bend radius greater than the material thickness and use the free bending method whenever possible. When the bending radius is large, the quality of the finished part and its future use are often not affected.

4. Bending Precision of the Press Brake Machine:

The bending accuracy requirement is a factor that needs to be carefully considered. It is this factor that determines whether you need to consider a CNC press brake machine or a NC hydraulic press brake. If the bending accuracy requires ±1° and cannot be changed, you must purchase CNC press brake machine.

The repeatability precision of the CNC hydraulic press brake slider is ±0.01mm, and the precise angle must be formed with such precision and a good mold. The repeatability precision of the NC hydraulic press brake machine slider is ±0.05mm, and the deviation of ±2~3° will generally occur under the condition of using a suitable mold. In addition, CNC press brakes are ready for rapid die set-up, which is an undeniable reason to consider when you need to bend many low-volume parts.

5. Purchase Press Brake Machine Tools:

Even if you have a shelf full of press brake tools, do not think that these tools are suitable for newly bought press brake machines. You need to ensure the height of the press brake upper punch and lower dies plus press brake stroke larger than press brake machine opening height.

For conventional molds, the deviation per foot should be around ±0.025mm, and the total length deviation should be no more than ±0.127mm. For fine grinding dies, the accuracy should be ±0.01mm per 25.4mm, and the total accuracy should not be greater than ±0.05mm. It is best to use fine ground dies for CNC press brakes and regular dies for NC press brake.

In conclusion, to purchase press brake machine, it is necessary for customers to consider workpieces, press brake deflection, bending radius, bending precision and press brake tools.

Buying a press brake machine can be a difficult decision. There are many different types of press brakes available in the market. Every type comes with further configuration. This can lead to confusion among even professional operators.

This article will provide a complete guide for buying a press brake. You will know about the factors to focus on and the pitfalls to avoid. Based on the information presented here, you can make a correct decision and get complete value for your investment.

Primary Factors to Consider When Buying a Press Brake

There are various factors at play when buying a press brake. Choose a press brake based on the particular factors that apply to you:

Tonnage Capacity

Tonnage capacity relates to the force that a press brake machine can apply. A higher force means the ability to bend a thicker material. Choose a tonnage capacity that can easily bend the metal in your particular application.

Bending Length

Bending length relates to the maximum length of the workpiece that a press brake can bend. The bending length of the machine depends on your particular applications. You require a long bending length if you intend to make large-scale metal parts.

Type of Press Brake

There are many different types of press brake machines. Each of these comes with its own set of advantages and limitations. You can choose the right press brake based on your use case. These different types of press brakes are:

Mechanical Press Brakes

The mechanical press brake is the most basic type of press brake. It is based on a flywheel and clutch mechanism. Electric motors power the flywheel clutch assembly. Mechanical press brakes have a large tonnage capability. They can easily bend three times their rated capacity. Additionally, they have a simple build leading to simpler maintenance. However, a major drawback of these brakes is their inability to stop midway. Once a cycle starts, the ram will complete the entire cycle motion.

Hydraulic Press Brakes

The hydraulic press brake uses the dynamics of water pressure to create the force for the bending. There are multiple hydraulic oil cylinders to provide various bending settings. This provides a greater number of options and adds to the bending precision. However, a hydraulic press brake is highly sensitive. Their operation should never exceed the rated tonnage value. Additionally, there is the risk of fluid leaks from the cylinders.

Electric Press Brakes

Electric press brakes use multiple servo brakes to move the bending ram. The servomotors provide accurate control over the bending angle. However, electric press brakes have severe limitations in tonnage capability. Additionally, electric press brake does not perform well for high volume production. It is also known as a CNC press brake machine.

Hybrid Press Brake

Hybrid press brakes combine the operation of hydraulic press brakes and electric press brakes. These machines have automatic start and stop operation. Additionally, replacement of electric motors with hydraulics provide a higher bending force. However, they require complex maintenance in case of a breakdown.

Pneumatic Press Brakes

Pneumatic press brakes replace oil cylinders with air. Compressed air can provide a high bending force necessary for most materials. These brakes have a lower bending prowess compared to hydraulic press brakes. However, there is no risk of fluid leakage in the operation.

Box and Pan Brakes

A box and pan brake is also known as a finger brake. These press brakes are simpler than other alternatives. They are used for small-scale application of bending thin sheet metal. They are named so because their main application is manually bending metal sheet for making boxes and pans.

Precision

Certain projects require more precision than others. Choosing a lower accuracy press brake for a high precision requirement can lead to rejection of most parts. Therefore, check the bending precision of the press brake before buying it. This value is generally listed in the product’s technical information page.

Material Thickness

Thicker materials are harder to bend. Check the thickest material that the press brake can bend. This will provide a better idea of whether it can adequately perform your operations. Different materials might have different thickness limits.

Bend Complexity

If your application requires multiple bends, choose a press brake that is capable of doing so. Otherwise, you might have to do multiple workpiece setups. This increases the setup time significantly, increasing the operating costs. It is better to invest these costs initially in a higher-capacity press brake.

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Production Efficiency

Different press brakes have a difference in bending speed. Use this value to find out how many parts it can create for you in a day. Choose a press brake if it fulfills your daily production volume requirements.

Operator Skill Level

Complex press brakes can provide a higher range of features and automation. However, it also requires a higher skill level of the operator. Consider the skilled operator’s availability before choosing a complex press brake option.

Secondary Factors to Consider For the Right Press Brake

Once the primary factors mentioned above are decided, you can evaluate further factors to make a better choice. These factors are:

Press Brake Configuration

There are two specialized configurations of press brakes available for niche applications. These configurations are:

Tandem Press Brake

A tandem press brake involves a setup of multiple individual press brakes. These press brakes are interconnected for a synchronized operation. A Tandem press brake is useful for bending a very long metal sheet. If a single press brake cannot fulfill your requirements, ensure that the press brake you choose has a tandem configuration.

Robotic Press Brake

A robotic press brake is a sheet metal bending solution with high automation. A robotic press brake is a great fit for fulfilling large production numbers. It can reduce the cost of production significantly for mass production of parts. However, these machines require frequent maintenance and good operator skill.

Type of Bending

There are three types of bending options with press brakes:

Air Bending

Air bending is the most popular press brake option. It applies to bending plate and sheet metal. Air bending uses a bottom tool in U-shape or V-shape press brake dies. The top tool is a radius punch. There is a large air pocket under the sheet metal due to the shape of the bottom tool. The punch applies force on the sheet metal, creating the bend. A single die can create multiple bend angles in air bending.

Bottom Bending

Bottom bending uses a similar radius punch and a V-shape bottom tool as air bending. However, it fully pushes the radius punch to the bottom die. Therefore, the obtained bend angle depends on the angle of the bottom die. It requires more force than air bending. It also requires specific dies for particular bend angles. However, it also translates to a better bend accuracy.

Coining

Coining further increases the force of the radius die. The applied tonnage not only bends the metal but also decreases its thickness. The tooling used in coining is exactly according to the particular bend specification. Coining has the highest consistency among all three press brake bends.

Safety Features

Modern press brake comes with a range of safety features to ensure the workforce remains unharmed. Ensure that your press has safety measures that fulfil the workplace safety compliance and even go beyond it.

Important Safety Measures For Press Brake

Safety measures won’t affect press brake operation. However, they will eliminate any probability of potential injury. Some of the important safety measures for press brakes are:

• Emergency Stop: There are many instances where a press brake operation can require an urgent stop. Ensure that your machine comes with an emergency stop feature.
• Guards: Guards ensure that any human organ such as the limb does not come under the machine during operation. These guards are usually physical barriers that eliminate human interference. Modern machines come with light sensors that stop machine operation if an object like a limb comes under the machine tool during operation.
• Interlocks: Interlocks ensure that the machine executes operation only if all the safety measures are fulfilled. For instance, leaving the guards open might halt machine operation until the guards are fully closed.
• Warning Signs: Warning signs on the machine indicate potential hazards with the machine. For instance, the electrical coverings of the machine should have electricity hazard signs. The gearing can have signs indicating potential working injury.
• Anti-Repeat Control: Anti-repeat controls ensure that multiple accidental presses of the pedals do not lead to multiple operations.
• Two-handed Control: Two-handed control eliminates accidental operation of the machine. The operator must use both hands to execute the press brake operation.
• Lockout: The lockout feature puts the machine to a complete standstill. This ensures that the machine is not started when it is in maintenance or repair mode.
• Safety Training: Manufacturers should ensure that the operator has sufficient safety training on the machine and its protocol.

Backgauge

Backgauge provides a precise positioning feature to the workpiece during press brake operation. It can be crucial when creating complex bends with good precision. Without a backgauge, the relative shift in workpiece position can result in high accumulated error. Backgauge is commonly used with CNC press brake machine for automation of complex bending.

Maintenance and Support

Maintenance support is a very crucial factor for a press brake. Press brakes are heavy industrial equipment, prone to occasional issues. Lack of maintenance support can lead to breakdown of the entire manufacturing operation temporarily, accumulating losses. Therefore, choose a reliable manufacturer to ensure that your machine is covered in the long term. Good manufacturers also provide every spare part at a quick notice.

Price

Press brakes have a wide price bracket. Cheaper options are pocket friendly but lack many features and automation. Expensive options can seem like a big initial investment. However, they may provide a better value for money by offering higher production. Choose a price point that matches your budget.

How much does a press brake cost?

An industrial press brake can cost anywhere from $5,000 to $500,000. The cheaper options are generally manual press brakes from unreliable suppliers. As you go up the price point, the degree of automation builds up. Additionally, you can always find a more rugged option by slightly adjusting your budget.

Warranty

A press brake should come with a warranty policy listing all the inclusions, exclusions, and the time frame. The warranty policy can indicate how much faith the manufacturer has in the product. Longer warranty periods also provide a peace of mind to the manufacturer.

Installation and Training

Buying a new press brake is only a part of the transition. The machine also requires expert installation. Additionally, the operators need training on the new equipment. It is better to go with a company that provides these options.

Controller Software

Evaluate the machine software when opting for an automated press brake. The software should be user friendly with adequate control for customization. Most good software come with preloaded programs for simple and commonly used sheet metal bends.

Space Requirements

Many users buy a press brake without evaluating the space they have in their workshop. This can cause serious problems during later operation. Measure the space available before evaluating the various press brake options. The space should include clearance for loading, unloading, and operation of the machine.

How big a press brake do you need?

The size of the press brake should be big enough to accommodate the size of the sheet metal. Additionally, sufficient space should be left around the press brake for operator movement, loading, and unloading. Maintenance process also requires certain space left empty around the equipment.

Manufacturer Reputation

Going for a branded press brake can seem slightly more expensive. However, the added expenses can provide a great amount of long-term comfort. Reputed manufacturers handle all customer concerns with an after-sales service team. Accurl is the leading press brake supplier globally in this regard.

Common Pitfalls When Buying a Press Brake

There are certain mistakes that users make when buying a press brake. These mistakes are easily avoidable if you know them beforehand. Here are these mistakes along with simple solutions to them:

• Buying a Generic Machine: Never choose a press brake just because it is popular. Evaluate your particular needs and then buy a tailored machine that can accommodate all your requirements. Buying a generic solution can lead to a machine occupying your workspace while not providing any acceptable results.
• Price Above Everything: Price should be a secondary factor when it comes to press brakes. Press brakes are going to be expensive since they are heavy industrial equipment. A cheaper option can breakdown frequently, accumulating losses due to downtimes.
• Uneducated Purchase: Thoroughly research the different options available in the market before putting your money on one. You might be able to get a better technology for the same price. You will also avoid buying problematic machines by reading user reviews online.
• Evaluating Maintenance Costs: Maintenance costs are a part of the machine investment. Consider how much it will cost to maintain the machine. Add this cost to the machine price when making comparisons.

Importance of Choosing the Right Press Brake

Making any error when buying a press brake can lead to losses and future disasters for your business. However, choosing the right machine can have several benefits, such as:

• Cost Saving: Even expensive press brakes can be a cost saving option. Spending extra on a good machine results in lower maintenance costs, lower breakdown rate, and less downtime.
• Productivity: Any issues with the press brake will lead to equipment breakdown. This will limit the number of products your machine can output. On the other hand, choosing the right machine can boost your productivity significantly.
• Safety: Inferior press brakes are cheaper but miss on many safety alternatives. Safety is an important factor for your workplace. Even minor injuries can result in major grievances and lawsuits.
• Bend Quality: The quality of your press brake will show in the quality of the sheet metal bends it creates. The right machine will create the right bend. This results in better customer satisfaction as well.

Where to Buy a Press Brake Machine?

Accurl is the leading global supplier of press brake machines. Accurl’s catalog has many product options, such as hydraulic press brake, CNC press brakes, tandem brake, servo press brake, etc.

Accurl machines are designed with utmost focus on build quality. These machines can handle all the heavy stress during operations. In case of any queries or problems, the brand provides prompt support. Spare parts are available whenever required, eliminating downtimes for the operation.

Endnotes

Spending a little extra time when buying a new press brake can mean saving a lot of money in the long term. The factors provided above will be more than sufficient to answer all your queries about choosing a press brake machine for your requirement.

For any more assistance, reach out to Accurl!

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