During the operation of a press brake you will soon realize that bending metals is anything but exact.  There are many factors related to press brake bending and an accurate part on a press brake that can vary from tooling to material springback. Newer machine systems have made great strides in adapting technology to compensate for press brake bending problems, however the science itself is far from perfect.  You as the operator or shop owner needs to know how you can avoid some of the basic problems associated with the press brake bending of accurate parts and our experts at Southern Fabricating Machinery Sales, Inc are here to help you achieve that goal.

Machine Positioning Accuracy
Whether your running a mechanical press brake or a newer electric press brake, press brake bending problems in metal forming likely are not in the accuracy or repeatability of the machine itself. Several quick checks on your machine can ensure it is repeating accurately such as placing a magnetic base dial indicator on the bed and measuring the stroke bottom repeatedly.  Normal press brakes will repeat that position within 0.0005” -0.001” and even more accurately so while under load in the normal press brake bending cycle. Also ensure your gibs on the ram are properly torqued

Like anything else, there are varying degrees of accuracy and thus prices, available in tooling. The more you spend on press brake tooling the more accuracy and repeatability you will generally get. As an example the cheapest press brake forming tools are simple “Cold Planed” tools usually in the 30-32RC hardness level. These “Soft” tools are cheap to buy, easy to cut/sectionalize and therefore easy to damage as well. They also only have a linear “accuracy of typically +/- 0.001 per foot. This lack of accuracy is compounded if the tools are cut into smaller segments, then mixed and matched for use in box forming applications.

Crowning is the ability to adjust for the natural deflection of the ram and bed in the press brake bending process. In years past shims were inserted under the dies to “lift” the dies just a few thousands of a n inch to eliminate the “Canoeing” effect on parts formed without sufficient “crown”.  Later advances added these features into the bed of the machine and even the die rail/holder. Sufficient and adjustable crowning is paramount for bending accurate, thin gage, long parts

More important than the accuracy of the machine or the tooling being used is the type, yield strength, exact thickness and springback of the material you are forming. Today any steel material thicker than 12 Gage likely comes from a mix of recycled metals we designate as type A36. This A36 material is sufficiently harder, stiffer and requires more tonnage then mild steels of generations past. Approximately 30% MORE tonnage is required then virgin mild steel as during the recycling processes these metals have been mixed with a variety of other steels containing properties such as nickel, chromium etc. which when added to mild steels greatly reduces their malleability/formability.  It is imperative to know what material you are working with, the bending/yield strength of it and the springback it will provide. By adjusting for these properties in the ram position, either through manual or automatic methods, your brake can form exacting angles over and over again.

At Southern Fabricating Machinery Sales , we are press brake bending experts. We know how to assist you in making the right press brake choices to avoid press brake bending problems. If you would like to discuss how a we can help you with your press brake bending needs just contact one of our experts today at 813-444-4555

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