Bending Basics from the Fabricator magazine
Bending Basics 2018
Bending Basics 2017
Modern CAD has automated traditional notch layout. But knowing how these notches are measured and made will help you choose the best notch for the job and, ultimately, make better parts.
Press brake bending: A deep dive into springback
Predicting springback isn’t an exact science, considering all the contributing variables. But doing a little math can get you close.
Change in metal fabrication: It is futile to resist
If you’re transitioning from coining or bottoming to air bending or, for that matter, making any process change, be sure to follow procedures based on physical realities, not on the way it’s always been done.
Press brake basics: Bending across the hem
How do you calculate the bend functions for parts that involve hems as well as bends across those hems? A hem has a specific elongation factor. Otherwise, you run the calculations and determine the bend lines as you would for any other part.
Steve Benson goes global and answers bending questions from around the world—about plate bending in Australia, tonnage considerations in India, offset bending in Mexico, and grain direction variables in the U.S.
When transitioning from bottoming bending to air bending, consider the material types and thicknesses you’ll be bending, invest in the right tools, and make sure your press brakes are up to the task.
Time for new press brake tooling
The inside bend radius is at the very heart of precision metal fabrication. To achieve the radius you want, you need to understand how tooling interacts with the workpiece, but you also need to make sure your machine and tools are in good working order.
Should one shop invest in a roll to bend large-diameter curves in thick aluminum or outsource the job? The answer depends on the return on investment, as well as the knowledge and expertise the job requires.
Press brake gauging conundrum
Forming a complex part requires creative thinking, and not only about how to gauge each bend. Every part has some error to account for slight variances in material thickness, bend deduction calculations, and more. The challenge lies in making sure the error is absorbed by a noncritical dimension.
Do precision fabricating rules apply to me?
Do the rules of precision bending apply to heavy plate fabrication? Of course, they do. After all, it’s really just a matter of scale.
Tooling choice when forming aluminum
When choosing tools to bend aluminum, as always, you need to consider the naturally floated radius as well as where the bend turns sharp. You also may consider forming certain aluminum grades in the annealed condition.
Breaking the time barrier
Press brake bending basics: Breaking the time barrier. Getting estimates right requires good information and, not least, good operators and engineers. Making accurate time estimates requires both complete information about the job at hand as well as technical talent, both in engineering and in press brake operation.
Bending Basics 2016
Proper measurement of formed parts
Measuring hems, acute angles, and unparalleled flanges aren’t difficult—if you have the right tools and dimensional information, and you know how to use both properly.
What makes an air bend sharp on a press brake
Press brake operators use rules of thumb when it comes to determining sharp bends. But what truly determines the point at which a bend turns sharp is the relationship between the punch nose radius, the tonnage required to form, and the shear strength of the material.
The meaning of the technical words mean everything
As parts become more complicated and our machines get more sophisticated and precise, there is a real need to be much more precise in our trade-related language
Determining the root causes of bending failure
When determining the root causes of part failure, look to not just the forming method and tooling, but also the quality of the material. A cheap material can be extremely costly over the long run.
How to locate the press brake backgauge position
When determining the backgauge position, you need to know the outside flange dimension and bend deduction, based on the actual radius you achieve.
Anytime the inside radius or material thickness varies, there will be a change in the bend deduction. This is just as true when bending plastic as it is when bending sheet metal.
When considering a new press brake purchase, focus on the tooling and forming method first. How will your staff react to changes? How steep will the learning curve be? Also, think about where your company is headed and the markets it serves.
Which press brake is best
No press brake is best for every application, but you can find a press brake that’s best for you. To find that press brake, you need to match what’s available—hydraulic, hybrid, electric, mechanical, and other styles, along with the tooling—with what your operation needs.
Applying the 20% rule to 6061 aluminum
Four areas to consider when bending include (1) formability; (2) thickness and bend radius; (3) tensile, yield, and elongation; and (4) how to deal with bending tempered materials. This month, Steven Benson applies these to forming 6061 aluminum.
Bending guru Steve Benson continues his discussion of notching, which has a symbiotic relationship with bending. Nowadays CAD systems take care of the layout calculations. Nonetheless, manual notch layout is still used for one-off products or in prototype shops.
Whether you are a press brake technician or you are programming in CAD, having a basic understanding of notching can lead to better products and a more efficient operation.
10-tips for bottoming aluminum
Bottom bending can work well for some aluminum grades, but it requires knowledgeable operators who fully grasp the bending method and know what precautions to take.
Bending Basics 2015
Grand Unifying Theory of Bending on a Press Brake
Press brake guru Steve Benson proposes a new theory of bending, altering some long-held labels and definitions and introducing new formulas. Those long-held definitions worked well, but these new definitions and formulas may help a press brake technician become even more accurate in predicting how a part will form.
The Grand Unifying Theory of Bending on a Press Brake pt 2
Radius bends—defined here as any bend with an inside radius greater than 125 percent of the material thickness—require careful calculation, not only because of their significant springback but also because of the tooling these bends require. This includes the use of relieved dies.
The Grand Unifying Theory of Bending on a Press Brake pt 3
In this installment of the Grand Unifying Theory of Bending, press brake guru Steve Benson describes bending calculations for aircraft tooling. He also covers the basics of bottoming.
The Grand Unifying Theory of Bending on a Press Brake pt 4
This month Steve Benson summarizes his grand unifying theory of radius, bend deduction, and die selection with a review and complete rundown of the bend calculations, from estimating springback to working the bend functions.
You can use some common rules of thumb to predict the inside bend radius when air forming, and the results you get are usually close enough, but with the help of a few online calculators, you can get even closer.
Using the 20 percent rule works well when calculating the floated radius in an air form, but what about the radius at different bend angles? To calculate this, we start with geometry to find the arc length and radius at different bend angles. We then manipulate these results by factoring in real-world bending conditions.
Forming aluminum on a press brake
Air bending soft aluminum has such a low tensile strength that it doesn’t take much for a narrow punch tip to penetrate the surface and turn the bend sharp.
How an air bend turns sharp
Why do air bends in cold-rolled steel turn sharp at an inside radius that’s about 63 percent the material thickness? It has to do with the relationship between forming forces and a material’s tensile and yield strength.
The 4-pillars of press brake tonnage limits
To ensure you always work within the tonnage limits of your press brake and tooling, first, calculate how much tonnage you need. Second, identify your tooling’s load limits. Third, calculate the sinking tonnage limit, which, if exceeded, can embed tooling into the ram or bed. Fourth, determine your press brakes’ centerline load limit.
Minimum versus recommended inside radius
A material’s minimum inside bend radius shows the smallest radius that’s physically possible in an air bend, though your machines and tooling may not be able to handle the tonnage. The recommended inside bend radius, such as those found on bend allowance charts for air bends, shows you what’s optimal in typical applications
Why buy new tooling for a sheet metal handbrake
When bending with a handbrake, you can use the tooling that came with the machine, but investing in a tool with a radius on the punch nose has its benefits.
6-steps to successful die selection for press brake
What inside bend radius you can achieve hinges on tonnage requirements and available die-opening widths
Bending Basics 2014
Why exactly does springback occur, and how can a technician predict it? Press brake guru Steve Benson covers the basic factors.
Strategies for forming offsets
If you pick the right offset tool for the job, you’ll find you will be able to produce many different offset geometries quickly and safely.
Streamlining press brake setups
Press brake setup is a critical part of doing any bending job correctly. By focusing on a few key areas—selection of tools and forming processes, easy-to-understand setup sheets, and ISO documentation—the press brake operator is in a much better position to succeed.
Why profound radius bending is a different animal
Large or profound-radius bends are those in which the inside bend radius exceeds eight times the material thickness, but is still too small to move to the plate roll. At this point, a press brake operator has to change his mindset before proceeding. This is not a typical bending job.
Bending Basics 2013
The fundamentals of heavy bending
When bending on a press brake, thicker and harder plates require larger minimum bend radii. Finding the true minimum bend radius for steel or aluminum plate requires a little research. Nonetheless, the answers are there, waiting for you to find them.
Why tonnage matters
Selecting the press brake and tooling for a job involves much more than just making sure there’s enough brute force. You need to calculate how much tonnage the job requires, then determine the best machine and tooling to handle the tonnage.
Why do die angles change
In air forming, the bend angle does not depend exclusively on the angle of the die. So why does the die angle change? There are two separate but overlapping answers; one relates to narrow die openings, and the other pertains to larger dies.
Finding the perfect die opening
By choosing a die opening as close to perfect as possible, your consistency will improve, your setup and run times will get shorter, and the risks of running into problems will be greatly reduced.
How the inside radius forms
Press brake guru Steve Benson describes how the method of bending—coining, bottom bending, or air forming—is very influential on how an inside bend radius is achieved.
Bending Basics 2012
The basics of applying bend functions
Why calculate values such as bend allowance, outside setback, and bend deductions? Because sometimes you will need to work your way around a bend on a print, and you may not have all the information you need to complete a flat pattern.
Dissecting bend deductions and die openings
Changing the die opening can dramatically change results during air forming. In precision sheet metal fabrication, choosing the correct die opening should not be a guessing game.